Polymers

27 pages, 5154 KiB

Open AccessReview

Surface Modification Progress for PLGA-Based Cell Scaffolds

by Bohua Yan, Yabing Hua, Jinyue Wang, Tianjiao Shao, Shan Wang, Xiang Gao and Jing Gao

Polymers 2024, 16(1), 165; https://doi.org/10.3390/polym16010165 - 4 Jan 2024

Cited by 2 | Viewed by 2933

Poly(lactic-glycolic acid) (PLGA) is a biocompatible bio-scaffold material, but its own hydrophobic and electrically neutral surface limits its application as a cell scaffold. Polymer materials, mimics ECM materials, and organic material have often been used as coating materials for PLGA cell scaffolds to [...] Read more.

Poly(lactic-glycolic acid) (PLGA) is a biocompatible bio-scaffold material, but its own hydrophobic and electrically neutral surface limits its application as a cell scaffold. Polymer materials, mimics ECM materials, and organic material have often been used as coating materials for PLGA cell scaffolds to improve the poor cell adhesion of PLGA and enhance tissue adaptation. These coating materials can be modified on the PLGA surface via simple physical or chemical methods, and coating multiple materials can simultaneously confer different functions to the PLGA scaffold; not only does this ensure stronger cell adhesion but it also modulates cell behavior and function. This approach to coating could facilitate the production of more PLGA-based cell scaffolds. This review focuses on the PLGA surface-modified materials, methods, and applications, and will provide guidance for PLGA surface modification. Full article

(This article belongs to the Special Issue Biomedical Applications of Polymeric Materials II)

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16 pages, 1847 KiB

Open AccessArticle

Integral Valorization of Posidonia oceanica Balls: An Abundant and Potential Biomass

by Rim Mnafki, Amaia Morales, Leyre Sillero, Ramzi Khiari, Younes Moussaoui and Jalel Labidi

Polymers 2024, 16(1), 164; https://doi.org/10.3390/polym16010164 - 4 Jan 2024

Viewed by 1462

Abstract

Posidonia oceanica balls (POB), a kind of seagrass, are a significant environmental issue since they are annually discharged onto beaches. Their current usefulness limits interest in their management and enhances the environmental problem. Therefore, in this research, the potential of this lignocellulosic biomass [...] Read more.

Posidonia oceanica balls (POB), a kind of seagrass, are a significant environmental issue since they are annually discharged onto beaches. Their current usefulness limits interest in their management and enhances the environmental problem. Therefore, in this research, the potential of this lignocellulosic biomass was studied from a holistic biorefinery point of view. To this end, an in-depth study was carried out to select the best pathway for the integral valorization of POBs. First, an autohydrolysis process was studied for the recovery of oligosaccharides. Then, a delignification stage was applied, where, in addition to studying different delignification methods, the influence of the autohydrolysis pre-treatment was also investigated. Finally, cellulose nanofibers (CNFs) were obtained through a chemo-mechanical treatment. The results showed that autohydrolysis not only improved the delignification process and its products, but also allowed the hemicelluloses to be valorized. Acetoformosolv delignification proved to be the most successful in terms of lignin and cellulose properties. However, alkaline delignification was able to extract the highest amount of lignin with low purity. CNFs were also successfully produced from bleached solids. Therefore, the potential of POB as a feedstock for a biorefinery was confirmed, and the pathway should be chosen according to the requirements of the desired end products. Full article

(This article belongs to the Special Issue Biopolymers from Renewable Sources)

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31 pages, 4237 KiB

Open AccessReview

Anthocyanin-Loaded Polymers as Promising Nature-Based, Responsive, and Bioactive Materials

by S.S. Rosales-Murillo, Julia Sánchez-Bodón, S.L. Hernández Olmos, M.F. Ibarra-Vázquez, L.G. Guerrero-Ramírez, L. Pérez-Álvarez and J.L. Vilas-Vilela

Polymers 2024, 16(1), 163; https://doi.org/10.3390/polym16010163 - 4 Jan 2024

Cited by 5 | Viewed by 2922

Abstract

Anthocyanins are a specific group of molecules found in nature that have recently received increasing attention due to their interesting biological and colorimetric properties that have been successfully applied in several fields such as food preservation and biomedicine. Consequently, reviews devoted to a [...] Read more.

Anthocyanins are a specific group of molecules found in nature that have recently received increasing attention due to their interesting biological and colorimetric properties that have been successfully applied in several fields such as food preservation and biomedicine. Consequently, reviews devoted to a general overview of these flavonoids have proliferated in recent years. Meanwhile, the incorporation of anthocyanins into polymeric systems has become an interesting strategy to widen the applicability of these molecules and develop new smart and functional polymers in the above cited areas. However, anthocyanin-based polymers have been scarcely reviewed in the literature. Accordingly, this review aims to be a systematic summary of the most recent approaches for the incorporation of anthocyanins into macro-, micro-, or nanostructured polymers. Moreover, this work describes the fundamentals of the applicability of smart anthocyanin-based polymers and offers an updated review of their most interesting applications as sensors, biological regulators, and active materials. Full article

(This article belongs to the Section Polymer Applications)

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18 pages, 4814 KiB

Open AccessArticle

Protein-Aided Synthesis of Copper-Integrated Polyaniline Nanocomposite Encapsulated with Reduced Graphene Oxide for Highly Sensitive Electrochemical Detection of Dimetridazole in Real Samples

by Kartik Behera, Bhuvanenthiran Mutharani, Yen-Hsiang Chang, Monika Kumari and Fang-Chyou Chiu

Polymers 2024, 16(1), 162; https://doi.org/10.3390/polym16010162 - 4 Jan 2024

Cited by 4 | Viewed by 1447

Abstract

Dimetridazole (DMZ) is a derivative of nitroimidazole and is a veterinary drug used as an antibiotic to treat bacterial or protozoal infections in poultry. The residues of DMZ cause harmful side effects in human beings. Thus, we have constructed a superior electrocatalyst for [...] Read more.

Dimetridazole (DMZ) is a derivative of nitroimidazole and is a veterinary drug used as an antibiotic to treat bacterial or protozoal infections in poultry. The residues of DMZ cause harmful side effects in human beings. Thus, we have constructed a superior electrocatalyst for DMZ detection. A copper (Cu)-integrated poly(aniline) (PANI) electrocatalyst (PANI-Cu@BSA) was prepared by using a one-step method of biomimetic mineralization and polymerization using bovine serum albumin (BSA) as a stabilizer. Then, the synthesized PANI-Cu@BSA was encapsulated with reduced graphene oxide (rGO) using an ultrasonication method. The PANI-Cu@BSA/rGO nanocomposite had superior water dispersibility, high electrical conductivity, and nanoscale particles. Moreover, a PANI-Cu@BSA/rGO nanocomposite-modified, screen-printed carbon electrode was used for the sensitive electrochemical detection of DMZ. In phosphate buffer solution, the PANI-Cu@BSA/rGO/SPCE displayed a current intensity greater than PANI-Cu@BSA/SPCE, rGO/SPCE, and bare SPCE. This is because PANI-Cu@BSA combined with rGO increases fast electron transfer between the electrode and analyte, and this synergy results in analyte–electrode junctions with extraordinary conductivity and active surface areas. PANI-Cu@BSA/rGO/SPCE had a low detection limit, a high sensitivity, and a linear range of 1.78 nM, 5.96 μA μM⁻¹ cm⁻², and 0.79 to 2057 μM, respectively. The selective examination of DMZ was achieved with interfering molecules, and the PANI-Cu@BSA/rGO/SPCE showed excellent selectivity, stability, repeatability, and practicability. Full article

(This article belongs to the Special Issue Functional Hybrid Polymeric Composites)

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(a) FE-SEM image of PANI-Cu@BSA and TEM images of (b) PANI-Cu@BSA and (c,d) PANI-Cu@BSA/rGO. Full article ">Figure 2
(a) FTIR spectra of BSA and PANI-Cu@BSA, (b) zeta of PANI-Cu@BSA and PANI-Cu@BSA/rGO, (c) UV spectra of BSA and PANI-Cu@BSA, and (d) Raman spectra of rGO and PANI-Cu@BSA/rGO. Full article ">Figure 3
Core-level XPS spectrum of (a) C 1s, (b) O 1s, (c) N 1s, and (d) Cu 2p for PANI-Cu@BSA/rGO. Full article ">Figure 4
(a) CV profile of the bare SPCE, PANI-Cu@BSA/SPCE, rGO/SPCE, and PANI-Cu@BSA/rGO/SPCE; (b) CV profile of PANI-Cu@BSA/rGO/SPCE at various scan rates (10–100 mV/s) in 5 mM [Fe(CN)6]3−/4−/0.5 M KCl solution; (c) linear plot of current (Ipa and Ipc) vs. (v (mV/s))1/2; (d) CV profile of the electrodes including bare, PANI-Cu@BSA, rGO, and PANI-Cu@BSA/rGO modified SPCEs in 150 µM DMZ containing 0.1 M PBS (pH 7) at 50 mV/s. Full article ">Figure 5
(a) CV profile of PANI-Cu@BSA/rGO/SPCE in different concentrations of DMZ (50–250 µM) at 50 mV/s, (b) linear plot of current vs. concentration of DMZ, (c,d) CV profile of the effect of loading level of PANI-Cu@BSA/rGO on the SPCE surface for the detection of DMZ at 50 mV/s, and (d) calibration plot of current vs. loading amount (µL). Full article ">Figure 6
(a) CV profile of PANI-Cu@BSA/rGO/SPCE in various pH ranges from 3 to 11 at 50 mV/s, (b) linear plot of current vs. pH, (c) linear plot of potential vs. pH values, (d) CV profile of PANI-Cu@BSA/rGO/SPCE at various scan rates (0.1 M PBS) from 20 to 120 mV/s, and (e) linear relationship between current and scan rate. Full article ">Figure 7
(a) LSV profile of PANI-Cu@BSA/rGO/SPCE at different concentrations of DMZ from 0.79 to 2057 µM at 50 mV/s, (b) calibration plot of DMZ vs. cathodic peak current (μA) (n = 3), (c) LSV profile of PANI-Cu@BSA/rGO/SPCE on the inferring effect of DMZ with various co-interfering compounds (AZP, CRD, DEX, IRT, LPN, Mg2+, Zn2+, and NFZ) at 50 mV/s, and (d) corresponding plot of current vs. interfering compounds. Full article ">Scheme 1
Pictorial representation of the synthesis process of the PANI-Cu@BSA/rGO. Full article ">Scheme 2
(a) Schematic illustration of possible interaction between the DMZ and PANI-Cu@BSA/rGO and (b) the plausible electroreduction mechanism of DMZ on the PANI-Cu@BSA/rGO/SPCE. Full article ">

17 pages, 12179 KiB

Open AccessArticle

Pyrolytic Modification of Heavy Coal Tar by Multi-Polymer Blending: Preparation of Ordered Carbonaceous Mesophase

by Lei Zhang, Chunjiang Liu, Yang Jia, Yidan Mu, Yao Yan and Pengcheng Huang

Polymers 2024, 16(1), 161; https://doi.org/10.3390/polym16010161 - 4 Jan 2024

Cited by 13 | Viewed by 1516

Abstract

In order to achieve the high-value utilization of heavy tar for the production of enhanced-performance graphite foam carbon, the carbon mesophase was ready from the heavy component of low-temperature coal tar, and the coal tar was modified by styrene-butadiene-styrene (SBS), polyethylene (PE) and [...] Read more.

In order to achieve the high-value utilization of heavy tar for the production of enhanced-performance graphite foam carbon, the carbon mesophase was ready from the heavy component of low-temperature coal tar, and the coal tar was modified by styrene-butadiene-styrene (SBS), polyethylene (PE) and ethylene-vinyl-acetate (EVA) copolymers. The order degree of the carbonite mesophase was analyzed using a polarizing microscope test, Fourier transform infrared spectroscopy and X-ray diffraction to screen out the most suitable copolymer type and addition amount. Furthermore, the mechanism of modification by this copolymer was analyzed. The results showed that adding SBS, PE and EVA to coal tar would affect the order of carbonaceous mesophase; however, at an addition rate of 10.0 wt.%, the linear-structure SBS copolymer with a styrene/butadiene ratio (S/B) of 30/70 exhibited the optimal degree of ordering in the carbonaceous mesophase. Its foam carbon prepared by polymer modification is the only one that forms a graphitized structure, with d₀₀₂ of 0.3430 nm, and the maximum values of Lc and La are 3.54 nm and 2.22 nm, respectively. This is because, under elevated pressure and high-temperature conditions, SBS underwent chain scission, releasing a more significant number of methyl and other free radicals that interacted with the coal tar constituents. As a result, it reduced the affinity density of heavy coal tar molecules, enhanced fluidity, promoted the stacking of condensed aromatic hydrocarbons and increased the content of soluble carbonaceous mesophase, ultimately leading to a more favorable alignment of the carbonaceous mesophase. Full article

(This article belongs to the Special Issue Carbon/Polymer Composite Materials)

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14 pages, 4955 KiB

Open AccessArticle

Prediction Models of Mechanical Properties of Jute/PLA Composite Based on X-ray Computed Tomography

by Xintao Zhao, Junteng Li, Shangbin Su and Ning Jiang

Polymers 2024, 16(1), 160; https://doi.org/10.3390/polym16010160 - 4 Jan 2024

Viewed by 1291

Abstract

The tensile strength and modulus of elasticity of a jute/polylactic acid (PLA) composite were found to vary nonlinearly with the loading angle of the specimen through the tensile test. The variation in these properties was related to the fiber orientation distribution (FOD) and [...] Read more.

The tensile strength and modulus of elasticity of a jute/polylactic acid (PLA) composite were found to vary nonlinearly with the loading angle of the specimen through the tensile test. The variation in these properties was related to the fiber orientation distribution (FOD) and fiber length distribution (FLD). In order to study the effects of the FOD and FLD of short fibers on the mechanical properties and to better predict the mechanical properties of short-fiber composites, the true distribution of short fibers in the composite was accurately obtained using X-ray computed tomography (XCT), in which about 70% of the jute fibers were less than 300 μm in length and the fibers were mainly distributed along the direction of mold flow. The probability density functions of the FOD and FLD were obtained by further analyzing the XCT data. Strength and elastic modulus prediction models applicable to short-fiber-reinforced polymer (SFRP) composites were created by modifying the laminate theory and the rule of mixtures using the probability density functions of the FOD and FLD. The experimental measurements were in good agreement with the model predictions. Full article

(This article belongs to the Special Issue Advanced Polymer Matrix Composites: Design, Manufacturing and Analysis)

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15 pages, 5102 KiB

Open AccessArticle

Synthesis of High-Value Bio-Based Polyamide 12,36 Microcellular Foams with Excellent Dimensional Stability and Shape Recovery Properties

by Chin-Wen Chen, Palraj Ranganathan, Bhuvanenthiran Mutharani, Jia-Wei Shiu, Syang-Peng Rwei, Yen-Hsiang Chang and Fang-Chyou Chiu

Polymers 2024, 16(1), 159; https://doi.org/10.3390/polym16010159 - 4 Jan 2024

Cited by 2 | Viewed by 1407

Abstract

The search for alternatives to petroleum-based thermoplastic polyamide elastomers (TPAEs) has recently drawn great interest. In this study, a bio-massed TPAE, PA12,36, was synthesized using 1,12-dodecanediamine (DDA) and fatty dimer acid (FDA, Pripol^TM1009) precursors via catalyst and solvent-free melt polycondensation. The [...] Read more.

The search for alternatives to petroleum-based thermoplastic polyamide elastomers (TPAEs) has recently drawn great interest. In this study, a bio-massed TPAE, PA12,36, was synthesized using 1,12-dodecanediamine (DDA) and fatty dimer acid (FDA, Pripol^TM1009) precursors via catalyst and solvent-free melt polycondensation. The molecular structure and molecular weight of the PA12,36 were characterized by ¹H NMR, FTIR, and GPC. PA12,36 displayed a low melting temperature of 85.8 °C, an initial degradation temperature of 425 °C, and a glass-transition temperature of 30.4 °C, whereas it sustained satisfactory tensile strength (10.0 MPa) and superior strain at break (1378%). Furthermore, PA12,36 was foamed by supercritical CO₂, and the cell size, cell density, and porosity were determined. The entangled long-chained FDA component generated a physically crosslinked network, which promoted the melt viscosity of PA12,36 against elongations of foam cell growth and increased foamability significantly. As a result, uniform structured cellular foams with a cell diameter of 15–24 µm and high cell density (10¹¹ cells/cm³–10¹² cells/cm³) were successfully achieved. The foaming window was widened from 76 to 81 °C, and the expansion ratio was increased from 4.8 to 9.6. Additionally, PA12,36 foam with a physically crosslinked structure presented a better creep shape recovery percentage (92–97.9%) and sturdier dimensional stability. This bio-based PA12,36 foam is a promising candidate to replace petroleum-based thermoplastic elastomer foams for engineering applications, particularly shoe soles. Full article

(This article belongs to the Special Issue Advances in Polymeric Foams)

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13 pages, 6273 KiB

Open AccessArticle

In Situ Polymerization of Antibacterial Modification Polyamide 66 with Au@Cu₂O-ZnO Ternary Heterojunction

by Xiang Li, Mi Zheng, Shikun Zhao, Zhiwen Cao, Kai Pan, Xinxing Feng, Hua Zhang, Min Zheng and Cheng Wang

Polymers 2024, 16(1), 158; https://doi.org/10.3390/polym16010158 - 4 Jan 2024

Viewed by 1416

Abstract

In situ polymerization has proven to be an effective route through which to introduce function materials into polyamide materials. In this work, a nano-heterojunction material was evenly dispersed in PA66 via in situ polymerization methods to yield the antimicrobial PA66. The composites showed [...] Read more.

In situ polymerization has proven to be an effective route through which to introduce function materials into polyamide materials. In this work, a nano-heterojunction material was evenly dispersed in PA66 via in situ polymerization methods to yield the antimicrobial PA66. The composites showed excellent antibacterial activity against Staphylococcus aureus and Escherichia coli, with strong mechanical properties. Fourier transform infrared spectroscopy (FTIR) showed that metal ions reacted with oxygen-containing functional groups. In addition, the shift of oxygen peaks in XPS spectra confirmed the occurrence of a complexation reaction. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) confirmed the effect of nano-heterojunction, which induced crystallization. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed uniform dispersion of heterojunctions in PA66. Tensile testing revealed decreased toughness with higher loadings. The nanocomposite polyamide material has good processing properties which can be processed into thin films, molds, and wires without changing the morphology, and can be widely used in a variety of fields. Full article

(This article belongs to the Section Polymer Composites and Nanocomposites)

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The preparation of PA66/Au@Cu2O-ZnO composites. Full article ">Figure 2
(a) TEM image of Au@Cu2O heterostructures; (b) TEM image of Au@Cu2O@ZnO ternary heterojunction; (c) SEM image of Au@Cu2O@ZnO ternary heterojunction. Full article ">Figure 3
SEM images of fracture sections: (a) pure PA66; (b) 400 ppm; (c) 800 ppm; (d) 1200 ppm. Full article ">Figure 4
TEM images of fracture sections: (a) PA66/Au@Cu2O-ZnO; (b–e) elemental mapping images of (c) Cu, (d) Au, and (e) Zn corresponding to (b) Au@Cu2O-ZnO compositions. Full article ">Figure 5
(a) FTIR spectrums of PA66 and PA66/Au@Cu2O-ZnO composites; (b) relative viscosities of PA66 and PA66/Au@Cu2O-ZnO composites. Full article ">Figure 6
C 1s and O 1s XPS spectra of PA66 and PA66/Au@Cu2O-ZnO composites. Full article ">Figure 7
DSC heating curves (a) and cooling curves (b) of PA66 and PA66/Au@Cu2O-ZnO composites. Full article ">Figure 8
XRD patterns of PA66 and PA66/Au@Cu2O-ZnO composites. Full article ">Figure 9
TG and DTG curves of PA66 and PA66/Au@Cu2O-ZnO composites under N2: (a) TG curves; (b) DTG curves. Full article ">Figure 10
Yield strength and elongation at break of PA66 and PA66/Au@Cu2O-ZnO composites. Full article ">

13 pages, 2320 KiB

Open AccessArticle

Theoretical and Experimental Research Concerning the Friction Forces Developed in Hydraulic Cylinder Coaxial Sealing Systems Made from Polymers

by Flavius Aurelian Sârbu, Felix Arnăuţ, Andrea Deaconescu and Tudor Deaconescu

Polymers 2024, 16(1), 157; https://doi.org/10.3390/polym16010157 - 4 Jan 2024

Cited by 1 | Viewed by 1154

Abstract

Optimizing the energy efficiency of hydraulic cylinder modern sealing systems requires, among other things, minimizing the developed friction forces. This can be achieved by manufacturing seals from polymer-based polytetrafluoroethylene-type materials (Virgin PTFE and filled PTFE) or from thermoplastic polyurethane elastomers. This paper presents [...] Read more.

Optimizing the energy efficiency of hydraulic cylinder modern sealing systems requires, among other things, minimizing the developed friction forces. This can be achieved by manufacturing seals from polymer-based polytetrafluoroethylene-type materials (Virgin PTFE and filled PTFE) or from thermoplastic polyurethane elastomers. This paper presents a procedure for calculating and experimentally determining the friction forces developed in the coaxial sealing systems of hydraulic cylinders pistons. Three sealing systems made from different materials were tested under varying conditions of pressure and velocity on an experimental test stand set up by the authors. The paper concludes with data and recommendations for the selection of the optimum seal material in order to maximize energy efficiency. Our comparative research conducted on the seal materials led to the conclusion that for reducing friction forces in hydraulic cylinders, Virgin PTFE is the most adequate. Full article

(This article belongs to the Special Issue Polymer Materials for Sensors and Actuators)

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11 pages, 1946 KiB

Open AccessArticle

Rigidity with Flexibility: Porous Triptycene Networks for Enhancing Methane Storage

by Fei Guo, Hui Ma, Bin-Bin Yang, Zhen Wang, Xiang-Gao Meng, Jian-Hua Bu and Chun Zhang

Polymers 2024, 16(1), 156; https://doi.org/10.3390/polym16010156 - 4 Jan 2024

Viewed by 1247

Abstract

In the pursuit of advancing materials for methane storage, a critical consideration arises given the prominence of natural gas (NG) as a clean transportation fuel, which holds substantial potential for alleviating the strain on both energy resources and the environment in the forthcoming [...] Read more.

In the pursuit of advancing materials for methane storage, a critical consideration arises given the prominence of natural gas (NG) as a clean transportation fuel, which holds substantial potential for alleviating the strain on both energy resources and the environment in the forthcoming decade. In this context, a novel approach is undertaken, employing the rigid triptycene as a foundational building block. This strategy is coupled with the incorporation of dichloromethane and 1,3-dichloropropane, serving as rigid and flexible linkers, respectively. This combination not only enables cost-effective fabrication but also expedites the creation of two distinct triptycene-based hypercrosslinked polymers (HCPs), identified as PTN-70 and PTN-71. Surprisingly, despite PTN-71 manifesting an inferior Brunauer–Emmett–Teller (BET) surface area when compared to the rigidly linked PTN-70, it showcases remarkably enhanced methane adsorption capabilities, particularly under high-pressure conditions. At a temperature of 275 K and a pressure of 95 bars, PTN-71 demonstrates an impressive methane adsorption capacity of 329 cm³ g⁻¹. This exceptional performance is attributed to the unique flexible network structure of PTN-71, which exhibits a pronounced swelling response when subjected to elevated pressure conditions, thus elucidating its superior methane adsorption characteristics. The development of these advanced materials not only signifies a significant stride in the realm of methane storage but also underscores the importance of tailoring the structural attributes of hypercrosslinked polymers for optimized gas adsorption performance. Full article

(This article belongs to the Special Issue Advances in the Preparation, Properties and Application of Polyurethane, Cellulose and Their Composites)

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23 pages, 24830 KiB

Open AccessArticle

Self-Healing Properties of Water Tree Damage in Multilayered Shell–Core-Structured Microcapsules/Cross-Linked Polyethylene Composites

by Bo Zhu, Hao Sun, Yaqi Zhu, Shengkun He and Ximu Han

Polymers 2024, 16(1), 155; https://doi.org/10.3390/polym16010155 - 4 Jan 2024

Cited by 1 | Viewed by 1220

Abstract

To investigate the effect of the structure of microcapsules on the properties of cross-linked polyethylene (XLPE) composites, three XLPE specimens filled with multilayered shell–core-structured microcapsules are designed. In this paper, the microcapsules are first analyzed morphologically and chemically. In addition, the effect of [...] Read more.

To investigate the effect of the structure of microcapsules on the properties of cross-linked polyethylene (XLPE) composites, three XLPE specimens filled with multilayered shell–core-structured microcapsules are designed. In this paper, the microcapsules are first analyzed morphologically and chemically. In addition, the effect of the microcapsule structure on the typical electrical properties of the composites is explored. Finally, the self-healing ability of XLPE specimens filled with microcapsules is verified. The results show that the SiO₂ on the surface of the trilayer shell–core microcapsules can make the microcapsules and the XLPE matrix have a better mechanical interlocking ability, which makes the typical properties of the trilayer shell–core microcapsules slightly better than those of the bilayer shell–core microcapsules. Moreover, when the bilayer shell–core or trilayer shell–core microcapsules rupture under the action of an electric field, the repair material reacts with the water tree under capillary action to consume the residual water while generating organic matter to fill in the cavity, thus repairing the damaged area of the water tree and ultimately achieving the self-healing of the composite water tree. Full article

(This article belongs to the Topic Polymers for Electrical Systems)

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16 pages, 20703 KiB

Open AccessArticle

Influence of Electrospinning Parameters on the Morphology of Electrospun Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Fibrous Membranes and Their Application as Potential Air Filtration Materials

by Yaohui Liu, Yanming Wang, Cheng-Hao Lee, Chi-Wai Kan and Xiaoying Lu

Polymers 2024, 16(1), 154; https://doi.org/10.3390/polym16010154 - 4 Jan 2024

Cited by 5 | Viewed by 1526

Abstract

A large number of non-degradable materials have severely damaged the ecological environment. Now, people are increasingly pursuing the use of environmentally friendly materials to replace traditional chemical materials. Polyhydroxyalkonates (PHAs) are receiving increasing attention because of the unique biodegradability and biocompatibility they offer. [...] Read more.

A large number of non-degradable materials have severely damaged the ecological environment. Now, people are increasingly pursuing the use of environmentally friendly materials to replace traditional chemical materials. Polyhydroxyalkonates (PHAs) are receiving increasing attention because of the unique biodegradability and biocompatibility they offer. However, the applications of PHAs are still limited due to high production costs and insufficient study. This project examines the optimal electrospinning parameters for the production of PHA-based fibrous membranes for air filtration. A common biodegradable polyester, Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), was electrospun into a nanofibrous membrane with a well-controlled surface microstructure. In order to produce smooth, bead-free fibers with micron-scale diameters, the effect of the process parameters (applied electric field, solution flow rate, inner diameter of hollow needle, and polymer concentration) on the electrospun fiber microstructure was optimized. The well-defined fibrous structure was optimized at an applied electric field of 20 kV, flow rate of 0.5 mL/h, solution concentration of 12 wt.%, and needle inner diameter of 0.21 mm. The morphology of the electrospun PHBV fibrous membrane was observed by scanning electron microscopy (SEM). Fourier transform infrared (FTIR) and Raman spectroscopy were used to explore the chemical signatures and phases of the electrospun PHBV nanofiber. The ball burst strength (BBS) was measured to assess the mechanical strength of the membrane. The small pore size of the nanofiber membranes ensured they had good application prospects in the field of air filtration. The particle filtration efficiency (PFE) of the optimized electrospun PHBV fibrous membrane was above 98% at standard atmospheric pressure. Full article

(This article belongs to the Section Polymer Applications)

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21 pages, 8274 KiB

Open AccessArticle

Preparation and Performance of Bitumen Modified by Melt-Blown Fabric of Waste Mask Based on Grey Relational and Radar Chart Analysis

by Peifeng Cheng, Chunmeng Zheng, Zhanming Zhang, Yiming Li, Kai Huang, Dezhong Yu and Yongcheng Ji

Polymers 2024, 16(1), 153; https://doi.org/10.3390/polym16010153 - 3 Jan 2024

Cited by 1 | Viewed by 1306

Abstract

To effectively utilize waste mask materials in road engineering and minimize resource waste, the melt-blown fabric (MBF) of waste masks was utilized to modify the virgin bitumen. The preparation process of MBF-modified bitumen was investigated, and the physical and rheological properties of bitumen [...] Read more.

To effectively utilize waste mask materials in road engineering and minimize resource waste, the melt-blown fabric (MBF) of waste masks was utilized to modify the virgin bitumen. The preparation process of MBF-modified bitumen was investigated, and the physical and rheological properties of bitumen were measured. Subsequently, the blending mechanism during preparation and the dispersion morphology of the modifier were explored. Finally, the pavement performance of the mixture was investigated, and a radar chart analysis was performed to quantitatively assess the effects of MBF modification. Results suggested that the recommended preparation process of shear time, shear rate, and shear temperature was 170 °C, 4000 r/min, and 15 min, respectively. MBF enhanced the high-temperature stability of the binder and weakened the temperature susceptibility. The modification was primarily a physical process. No network structure and agglomeration formed in the bitumen after modification. The addition of MBF significantly improved the resistance of the asphalt mixture to a high-temperature deformation and water damage but harmed its low-temperature crack resistance. The comprehensive assessment results of 0% (

f_{1}

), 1% (

f_{2}

), 3% (

f_{3}

), and 5% (

f_{4}

) MBF to improve the properties of the mixture were in the following order:

f_{3} > f_{4} > f_{2} > f_{1}

, where the impact of 3% MBF was the most significant, followed by 5% and 1% MBF. Full article

(This article belongs to the Section Polymer Processing and Engineering)

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13 pages, 3853 KiB

Open AccessArticle

Epoxy-Acrylic Polymer In-Situ Filling Cell Lumen and Bonding Cell Wall for Wood Reinforcement and Stabilization

by Yiliang Liu, Jilong Fan, Fengbiao Yao, Xudong Gao, Yueying Zhao, Baoxuan Liu, Xiaoying Dong and Yongfeng Li

Polymers 2024, 16(1), 152; https://doi.org/10.3390/polym16010152 - 3 Jan 2024

Cited by 1 | Viewed by 1250

Abstract

Under a global carbon-neutralizing environment, renewable wood is a viable alternative to non-renewable resources due to its abundance and high specific strength. However, fast-growing wood is hard to be applied extensively due to low mechanical strength and poor dimensional stability and durability. In [...] Read more.

Under a global carbon-neutralizing environment, renewable wood is a viable alternative to non-renewable resources due to its abundance and high specific strength. However, fast-growing wood is hard to be applied extensively due to low mechanical strength and poor dimensional stability and durability. In this study, epoxy-acrylic resin-modified wood was prepared by forming a functional monomer system with three monomers [glycidyl methacrylate (GMA), maleic anhydride (MAN), and polyethylene glycol-200-dimethylacrylic acid (PEGDMA)] and filling into the wood cell cavity. The results showed that in the case of an optimal monomer system of nGMA:nPEGDMA = 20:1 and an optimal MAN dosage of 6%, the conversion rate of monomers reached 98.01%, the cell cavity was evenly filled by the polymer, with the cell wall chemically bonded. Thus, a bonding strength of as high as 1.13 MPa, a bending strength of 112.6 MPa and an impact toughness of 74.85 KJ/m² were applied to the modified wood, which presented excellent dimensional stability (720 h water absorption: 26%, and volume expansion ratio: 5.04%) and rot resistance (loss rates from white rot and brown rot: 3.05% and 0.67%). Additionally, polymer-modified wood also exhibited excellent wear resistance and heat stability. This study reports a novel approach for building new environmentally friendly wood with high strength and toughness and good structural stability and durability. Full article

(This article belongs to the Special Issue Wood Polymer Composites: Properties, Processing and Applications)

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Schematic diagram of epoxy-acrylic polymer-modified (through in situ filling) aspen wood realizing compatibility of interface bonding and high performance. Full article ">Figure 2
Optimization of monomer ratio based on the interfacial bonding strength between three kinds of man-made board substrates and modified veneer: optimization of GMA/PEGDMA ratio based on (a) paticleboard, (b) fiberboard and (c) plywood; optimization of MAN dosage based on (d) paticleboard, (e) fiberboard and (f) plywood; microstructure of the bonding interface of modified veneered (g) paticleboard, (h) fiberboard and (i) plywood at the optimal ratio. Full article ">Figure 3
Dimensional stability and rot resistance of epoxy-acrylic polymer-modified wood: (a) comparison of resin conversion rate between monomer system and wood impregnated in other resins, (b) SEM microstructure of the cross-section of the modified wood, (c) FTIR curves of modified wood and unmodified wood, (d) water absorption rate, (e) water absorption volume expansion rate and (f) anti-expansion rate, (g) rot resistance value of modified wood and unmodified wood, (h) SEM microstructure of unmodified wood after wood preservation test, (i) SEM microstructure of modified wood after wood preservation test (the inner illustration is the image of modified wood not corroded by rot fungi in the wood preservation test). Full article ">Figure 4
Impact toughness of polymer-modified wood: (a) XRD curves of polymer-modified wood and unmodified wood, (b) schematic diagram of impact toughness test, (c) comparison of impact toughness between polymer-modified wood and unmodified wood and (d) SEM microstructure of impact fracture surface of polymer-modified wood. Full article ">Figure 5
Mechanical properties and heat stability of polymer-modified wood: (a) bending strength, (b) compressive strength (rift grain), (c) hardness, (d) wear value, (e) TG curves and (f) DTG curves. Full article ">

17 pages, 4037 KiB

Open AccessArticle

Preparation of Cationic Polyacrylamide Suspension and Its Application in Oilfield Wastewater Treatment

by Zhongjin Wei, Wenjun Long, Shaohua Li, Yu Zhao, Siting Yu and Fengshan Zhou

Polymers 2024, 16(1), 151; https://doi.org/10.3390/polym16010151 - 3 Jan 2024

Cited by 2 | Viewed by 1993

Abstract

Cationic polyacrylamide (CPAM) solid particle is one of the most commonly used organic polymer flocculants in oilfield wastewater treatment, but it poses some problems, such as a slow dissolution rate and an easy formation into a “fish-eye” in the process of diluting into [...] Read more.

Cationic polyacrylamide (CPAM) solid particle is one of the most commonly used organic polymer flocculants in oilfield wastewater treatment, but it poses some problems, such as a slow dissolution rate and an easy formation into a “fish-eye” in the process of diluting into aqueous solution. However, the current liquid CPAM products also have some problems, such as low effective content, poor storage stability, degradation in a short time, and high preparation costs. In this paper, a CPAM suspension was successfully prepared with 50.00% CPAM fine powder, 46.87% oil phase solvent, 0.63% separating agent, 1.56% emulsifying and dispersing agent, and 0.94% rheology modifier. This suspension has an effective content of 50.00%. It also showed no separation in 7 days of storage at room temperature, no separation in 30 min of centrifugation at a speed of 2000 rpm, and diluted to a 0.40% solution in just 16.00 min. For 1000 NTU of diatomite-simulated wastewater, the optimal turbidity removal rate of the suspension was 99.50%, which was higher than the optimal turbidity removal rate of 98.40% for the inorganic flocculant polymeric aluminum chloride (PAC). For oilfield wastewater, the optimal turbidity removal rate of the CPAM suspension was 35.60%, which was higher than the optimal turbidity removal rate of 28.40% for solid particle CPAM. In a scale-up test, the CPAM suspension achieved a good application effect. Full article

(This article belongs to the Special Issue Recent Advances in Functional Polymer Materials for Water Treatment)

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Schematic diagram of the CPAM suspension preparation. Full article ">Figure 2
The adsorption mechanism of F-Silica. Full article ">Figure 3
Effects of F-Silica: (a) trend of the apparent viscosity of the suspension (at 50% effective content of the suspension); (b) trend of dissolution time (dilution concentrations of 0.20% and 0.40%). Full article ">Figure 4
Effects of emulsifying and dispersing agent: (a) dissolution time (dilution concentration of 0.40%); (b) synergistic effect of CTAB and Span 80 (dilution concentration of 0.40%). Full article ">Figure 5
Effects of the rheology modifier: (a) suspension separation rate (centrifuged at 2000 rpm for 30 min); (b) dissolution time (dilution concentration of 0.40%); (c) room temperature storage; (d) mechanism of shear force enhancement. Full article ">Figure 6
Image of the suspension under an optical microscope: (a) 200× magnification; (b) 400× magnification. Full article ">Figure 7
Comparison of flocculation and water purification performance of different products: (a) simulated wastewater (organic polymer flocculant, dilution concentrations of 0.20%); (b) simulated wastewater (inorganic flocculant, dilution concentrations of 10.00%); (c) oilfield wastewater (dilution concentrations of 0.20%); (d) water purification effect. Full article ">Figure 8
The wastewater treatment process for the wastewater station. Full article ">Figure 9
Field dosing situation: (a) CPAM particle dosing tank; (b) CPAM suspension dosing tank; (c) CPAM suspension for dilution; (d) after full dissolution. Full article ">Figure 10
Wastewater before and after field dosing: (a) wastewater in the air flotation machine before dosing; (b) wastewater in the air flotation machine after dosing; (c) wastewater at the outlet before dosing; (d) wastewater at the outlet after dosing. Full article ">

10 pages, 6467 KiB

Open AccessArticle

Flexible Film Bulk Acoustic Wave Filter Based on Poly(vinylidene fluoride-trifluorethylene)

by Xiangyu He, Jiaqi Lu, Feng Gao, Shurong Dong, Juan Li, Hao Jin and Jikui Luo

Polymers 2024, 16(1), 150; https://doi.org/10.3390/polym16010150 - 3 Jan 2024

Cited by 2 | Viewed by 1158

Abstract

Poly(vinylidene fluoride-trifluorethylene) (P(VDF-TrFE)) has promising potential applications in radio-frequency filters due to their excellent piezoelectric properties, flexibility, and stability. In this paper, a flexible film bulk acoustic wave filter is investigated based on P(VDF-TrFE) as piezoelectric film. A new method based on three-step [...] Read more.

Poly(vinylidene fluoride-trifluorethylene) (P(VDF-TrFE)) has promising potential applications in radio-frequency filters due to their excellent piezoelectric properties, flexibility, and stability. In this paper, a flexible film bulk acoustic wave filter is investigated based on P(VDF-TrFE) as piezoelectric film. A new method based on three-step annealing is developed to efficiently remove the porosity inside the P(VDF-TrFE) films so as to improve its properties. The obtained film achieved high β-phase content beyond 80% and a high piezoelectric coefficient of 27.75 pm/V. Based on the low porosity β-phase films, a flexible wide-band RF filter is designed, which consists of a bulk acoustic wave resonator and lumped inductor-capacitor elements as a hybrid configuration. The resonator sets the filter’s center frequency, while the lumped LC-based matching network extends the bandwidth and enhances out-of-band rejection. The testing results of the proposed wide-band filter show its good performance, with 12.5% fractional bandwidth and an insertion loss of 3.1 dB. To verify the possibility of folding and stacking the flexible bulk acoustic wave devices for high-density multi-filter integration in MIMO communication, bending tests of the filter are also conducted with the bending strain range up to 5500 με. The testing results show no noticeable performance degradation after four bending cycles. This work demonstrates the potential of β-phase P(VDF-TrFE) bulk acoustic wave filters to expand the scope of future flexible radio-frequency filter applications. Full article

(This article belongs to the Special Issue Research Progress of Polymer-Based Sensors)

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The fabrication process of the P(VDF-TrFE) thin films. Full article ">Figure 2
P(VDF-TrFE) Thin Films: (a) sample S1 cross-section; (b) sample S2 cross-section (c) XRD curves of sample S1 and S2; (d) FTIR spectra of sample S1 and S2; (e) amplitude versus applied voltage of piezoresponse hysteresis loops in P(VDF-TrFE) films; (f) phase versus applied voltage. Full article ">Figure 3
(a) Schematic diagram of the structure of the P(VDF-TrFE) BAW Resonators; (b) simulated S11 and Z curves of P(VDF-TrFE) BAW with 20 μm P(VDF-TrFE) film. Full article ">Figure 4
(a) A photo and drawing of the fabricated P(VDF-TrFE) BAW; S11 and Z spectra of (b) the BAW with a 70 μm P(VDF-TrFE) film; (c) with a 20 μm P(VDF-TrFE) film; (d) with a 10 μm P(VDF-TrFE) film, respectively. Full article ">Figure 5
The proposed P(VDF-TrFE) BAW filter. (a) Circuit diagram for the proposed BAW filter; (b) a photo of the fabricated filter. Full article ">Figure 6
(a) The frequency response of fabricated P(VDF-TrFE) BAW filter; (b) matching networks and the parallel inductor. Full article ">Figure 7
The flexible P(VDF−TrFE) BAW filter (a) performance of resonator under different strains; (b) performance of filter under different strains; (c) bending testing. Full article ">

25 pages, 4751 KiB

Open AccessArticle

Cellulose Functionalization Using N-Heterocyclic-Based Leaving Group Chemistry

by Arvind Negi and Ali R. Tehrani-Bagha

Polymers 2024, 16(1), 149; https://doi.org/10.3390/polym16010149 - 3 Jan 2024

Cited by 2 | Viewed by 1927

Abstract

There has been continuous interest in developing novel activators that facilitate the functionalization of cellulosic materials. In this paper, we developed a strategy in which trisubstituted triazinium salts act as cellulose preactivators. As leaving groups, these triazinium salts utilize N-heterocycles (pyridine, imidazole, [...] Read more.

There has been continuous interest in developing novel activators that facilitate the functionalization of cellulosic materials. In this paper, we developed a strategy in which trisubstituted triazinium salts act as cellulose preactivators. As leaving groups, these triazinium salts utilize N-heterocycles (pyridine, imidazole, and nicotinic acid). Initially, we optimized the synthetic route for developing these novel cellulose preactivators (triazinium salts), whose structures were confirmed using NMR spectroscopy. The surface zeta potential of cellulose changed from a negative value to a positive one after preactivation due to the cationic nature of these preactivators. To enhance the scope of the study, we functionalized the cellulose-preactivated materials with a series of amine- or hydroxy-containing aliphatic and aromatic hydrocarbons, nucleophilic amino acids (cysteine), colorants (2-aminoanthraquinone and 2-amino-3-methyl-anthraquinone), and biopolymer (zein protein). The treated samples were analyzed using FTIR, time-gated Raman spectroscopy, and reflection spectroscopy, and the success of the functionalization process was validated. To widen the scope of such chemistries, we synthesized four reactive agents containing N-heterocyclic-based leaving groups (pyridine and nicotinic acid) and successfully functionalized cellulose with them in one step. The proposed single- and two-step functionalization approaches will provide opportunities for chemically linking various chemical compounds to cellulose for different applications. Full article

(This article belongs to the Special Issue Advances in Natural Cellulose)

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Full article ">Figure 1
The chemical structures of (A) synthesized preactivators (PrAct-1, PrAct-2, and PrAct-3), (B) synthesized activators (Act-1, Act-2, Act-3, and Act-4), (C) cationizing agents used to study the optimization and strength of preactivators, and (D) amine-containing colorants. Full article ">Figure 2
(a). Chemical reactivity: compared zeta potentials of preactivators with cellulose, including the zeta potential of the cellulose samples after reaction with preactivators at various concentrations. The zeta potential of the untreated cellulose sample was −9.63 mV. (b). A comparison of FTIR dips of nontreated cellulose with PrAct-3-treated cellulose (showing COOH stretching, C=C aromatic stretching, C-H stretching, and O-H stretching). Full article ">Figure 3
Raman spectral characterization of (A) cotton fabric; (B) localized fiber (in focus) irradiated with a 532 nm laser; (C) time-gated 3D spectra of zein-treated cotton fabric; and (D) Raman spectral characterization of zein-treated cotton fabric extracted in the 5.1–5.3 ns range. Full article ">Figure 3 Cont.
Raman spectral characterization of (A) cotton fabric; (B) localized fiber (in focus) irradiated with a 532 nm laser; (C) time-gated 3D spectra of zein-treated cotton fabric; and (D) Raman spectral characterization of zein-treated cotton fabric extracted in the 5.1–5.3 ns range. Full article ">Figure 4
(a) Time-gated Raman spectra of 1,5-pentadiol-treated cotton fabric, (b) time-gated Raman spectra of 1-Napthol-treated cotton fabric, (c) comparative FTIR spectra of PrAct-3 preactivated cellulose fabric, Act-1, and Act-4-activated cellulose fabric with aromatic hydrocarbon-functionalized cellulose fabric. Full article ">Figure 5
FTIR spectra of nonactivated cellulose fiber (right-hand side) and Act-1-treated cellulose fiber (left-hand side). Full article ">Scheme 1
Cellulose functionalizations. (A). Two-step approach. (B). One-step approach. Full article ">Scheme 2
Synthetic route devised for the development of preactivators and side products. Full article ">Scheme 3
Structural features indicating the numbering of atoms for 3JHH COSY, 1H-NMR, and 13C-NMR, and the correlation of vicinal protons in PrAct-1 (A–C), PrAct-2 (D–F), and PrAct-3 (G–I). Full article ">Scheme 4
Synthesis routes of four reactive chemicals (Act-1, Act-2, Act-3, and Act-4). Full article ">

17 pages, 4838 KiB

Open AccessArticle

Mucoadhesive Hybrid System of Silk Fibroin Nanoparticles and Thermosensitive In Situ Hydrogel for Amphotericin B Delivery: A Potential Option for Fungal Keratitis Treatment

by Pratthana Chomchalao, Nuttawut Saelim, Supaporn Lamlertthon, Premnapa Sisopa and Waree Tiyaboonchai

Polymers 2024, 16(1), 148; https://doi.org/10.3390/polym16010148 - 3 Jan 2024

Cited by 4 | Viewed by 1739

Abstract

The purpose of this work was to investigate the feasibility of a novel ophthalmic formulation of amphotericin B-encapsulated silk fibroin nanoparticles incorporated in situ hydrogel (AmB-FNPs ISG) for fungal keratitis (FK) treatment. AmB-FNPs ISG composites were successfully developed and have shown optimized physicochemical [...] Read more.

The purpose of this work was to investigate the feasibility of a novel ophthalmic formulation of amphotericin B-encapsulated silk fibroin nanoparticles incorporated in situ hydrogel (AmB-FNPs ISG) for fungal keratitis (FK) treatment. AmB-FNPs ISG composites were successfully developed and have shown optimized physicochemical properties for ocular drug delivery. Antifungal effects against Candida albicans and in vitro ocular irritation using corneal epithelial cells were performed to evaluate the efficacy and safety of the composite formulations. The combined system of AmB-FNPs-ISG exhibited effective antifungal activity and showed significantly less toxicity to HCE cells than commercial AmB. In vitro and ex vivo mucoadhesive tests demonstrated that the combination of silk fibroin nanoparticles with in situ hydrogels could enhance the adhesion ability of the particles on the ocular surface for more than 6 h, which would increase the ocular retention time of AmB and reduce the frequency of administration during the treatment. In addition, AmB-FNP-PEG ISG showed good physical and chemical stability under storage condition for 90 days. These findings indicate that AmB-FNP-PEG ISG has a great potential and be used in mucoadhesive AmB eye drops for FK treatment. Full article

(This article belongs to the Special Issue Development and Application of Bio-Based Polymers)

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17 pages, 6974 KiB

Open AccessArticle

A Global Approach to Modeling Injection Molding

by Przemysław Narowski and Krzysztof Wilczyński

Polymers 2024, 16(1), 147; https://doi.org/10.3390/polym16010147 - 3 Jan 2024

Viewed by 2210

Abstract

A problem of modeling plastic injection forming (molding) is presented, including both the plasticizing system of the injection-forming machine and the mold. When modeling the plastic flow in the mold, the input quantities are essentially unknown, e.g., the plastic melt temperature. Thus, a [...] Read more.

A problem of modeling plastic injection forming (molding) is presented, including both the plasticizing system of the injection-forming machine and the mold. When modeling the plastic flow in the mold, the input quantities are essentially unknown, e.g., the plastic melt temperature. Thus, a comprehensive (global) model of the injection-forming process is needed for the flow in the plasticizing system and in the mold. The process output quantities from the plasticizing system will be the input quantities for the mold. When modeling the plastic flow in the injection-forming machine, a comprehensive approach should be applied to consider the solid material conveying, material plasticizing, and the material melt flow. The model of material plasticizing is a basis for building such global models. In this research, the effect of the flow (including plasticizing) in the injection-forming machine on the flow in the mold is studied by simulation (using Moldex3D 2023R3OR 64-bit software) and experimentation. These studies are carried out for the injection forming of selected material using a specialized spiral mold. Simulations performed with the use of Moldex3D software for the plasticizing system significantly improved the accuracy of the simulation of the flow in the mold. However, the best results were obtained using experimental data (plastic melt temperature) as input quantities for mold filling simulations. The novel concepts of injection-forming process modeling based on our previous experimentations are also discussed. Full article

(This article belongs to the Special Issue Injection Molding Process in Polymer Processing)

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15 pages, 4422 KiB

Open AccessArticle

Influence of Dilution on the Mechanical Properties and Microstructure of Polyurethane-Cement Based Composite Surface Coating

by Chao Xie, Yufeng Shi, Ping Wu, Binqiang Sun and Yaqiang Yue

Polymers 2024, 16(1), 146; https://doi.org/10.3390/polym16010146 - 3 Jan 2024

Cited by 2 | Viewed by 1119

Abstract

Polyurethane-cement composite are widely used in modern civil engineering, and the method of adding diluent is often used to adjust the construction process to adapt to the engineering environment. Studies have shown that the addition of diluent impacts the performance of polyurethane-cement based [...] Read more.

Polyurethane-cement composite are widely used in modern civil engineering, and the method of adding diluent is often used to adjust the construction process to adapt to the engineering environment. Studies have shown that the addition of diluent impacts the performance of polyurethane-cement based composite surface coatings, but there have been few reports on the influence of diluent content on the mechanical properties and microstructure of the coatings. To address this, polyurethane coatings with different diluent contents were prepared, and positron annihilation lifetime spectroscopy was used to test the microstructure of the coatings. The tensile strength and elongation at rupture were tested using a universal material testing machine, and the fracture interface morphology of each coating was observed by scanning electron microscopy. Finally, the correlation between the microstructure parameters and the mechanical properties of the coating was analyzed using grey relation theory. The results demonstrated that with the increase in diluent content, (i) the average radius of the free volume hole (R) and the free volume fraction (F_V) of the coating both showed a trend of first decreasing and then increasing. The value of R was between 3.04 and 3.24 Å, and the value of F_V was between 2.08 and 2.84%. (ii) The tensile strength of the coating increased first and then decreased, while the elongation at rupture decreased first and then increased. Among them, the value of tensile strength was between 3.23 and 4.02 MPa, and the value of elongation at fracture was between 49.34 and 63.04%. In addition, the free volume in polymers plays a crucial role in facilitating the migration of molecular chain segments and is closely related to the macroscopic mechanical properties of polymers. A correlation analysis showed that the R value of the coating had the greatest influence on its tensile strength, while F_V showed a higher correlation with the elongation at rupture. Full article

(This article belongs to the Special Issue Developments in the Thermal, Electrical and Mechanical Properties of Polymer-Based Composites)

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13 pages, 3226 KiB

Open AccessArticle

Polysaccharides Produced by Plant Growth-Promoting Rhizobacteria Strain Burkholderia sp. BK01 Enhance Salt Stress Tolerance to Arabidopsis thaliana

by Enni Chen, Changsheng Yang, Weiyi Tao and Shuang Li

Polymers 2024, 16(1), 145; https://doi.org/10.3390/polym16010145 - 3 Jan 2024

Cited by 4 | Viewed by 1680

Abstract

Salt stress is one of the most serious abiotic stresses leading to reduced agricultural productivity. Polysaccharides from seaweed have been used as biostimulants to promote crop growth and improve plant resistance to abiotic stress. In this study, PGPR strain Burkholderia sp. BK01 was [...] Read more.

Salt stress is one of the most serious abiotic stresses leading to reduced agricultural productivity. Polysaccharides from seaweed have been used as biostimulants to promote crop growth and improve plant resistance to abiotic stress. In this study, PGPR strain Burkholderia sp. BK01 was isolated from the rhizosphere of wheat, and it was characterized for phosphorus (Pi) dissolution, indole-3-acetic acid (IAA) production, ammonia (NH₃) and exopolysaccharides (EPS). In particular, strain BK01 can efficiently produce extracellular polysaccharide with a yield of 12.86 g/L, using sorbitol as carbon source. BK01 EPS was identified as an heteropolysaccharide with Mw 3.559 × 10⁶ Da, composed of (D)-galactose (75.3%), (D)-glucose (5.5%), (L)-rhamnose (5.5%), (D)-galactouronic acid (4.9%) and (D)-glucuronic acid (8.8%). The present work aims to highlight the effect of the BK01 EPS on growth and biochemical changes in Arabidopsis thaliana under salt stress (100 mM). The purified BK01 EPS at a concentration of 100 mg/L efficiently promoted the growth of plants in pot assays, improved the chlorophyll content, enhanced the activities of SOD, POD and CAT, and decreased the content of MDA. This results suggested that the polysaccharides produced by PGPR strain Burkholderia sp. BK01 can be used as biostimulants to promote plant growth and improve plant resistance to salt stress. Full article

(This article belongs to the Special Issue Natural Polysaccharides and Their Biological Applications)

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Full article ">Figure 1
Morphological characteristics and identification of Burkholderia sp. BK01. (A) Scanning electron micrograph of the strain BK01. (B) The colony morphology of the strain BK01. (C) Phylogenetic analysis of the isolate BK01 based on the sequencing of the 16S rDNA. The scale bar indicates 0.005 substitutions per nucleotide position. Full article ">Figure 2
(A) Pi solubilization and pH in broth. (B) Yields of IAA produced by BK01. (C) Ammonia production tests of Burkholderia strains (1: Burkholderia sp. BK01; 2: Burkholderia cepacia ATCC 25416; 3. Burkholderia sp. CICC 24715). Values are three replicates. Full article ">Figure 3
Yield of EPS, viscosity of fermentation broth, and biomass (OD600). Values are three replicates. Full article ">Figure 4
Phenotypes of Arabidopsis thaliana after 7 days of NaCl treatment ((A), control; (B), 100 mM NaCl; (C), BKEPS 100 ppm + 100 mM NaCl; (D), BKEPS 100 ppm); on the far right is a seedling tray with uniform specifications. Full article ">Figure 5
K+/Na+ ratios in Arabidopsis seedlings under normal (CK and BKEPS) and salt stress (NaCl and BKEPS + NaCl) conditions. Values are the mean ± LSD of three replicates. Different letters indicate significant differences at p < 0.05. Full article ">Figure 6
MDA contents (A), and CAT (B), POD (C), SOD (D) activities in Arabidopsis seedlings. Values are the mean ± LSD of three replicates. Different letters indicate significant differences at p < 0.05. MDA, malondialdehyde; SOD, superoxide dismutase; POD, peroxidase; CAT, catalase. Full article ">Figure 7
Proline contents in Arabidopsis seedlings. Values are the mean ± LSD of three replicates. Different letters indicate significant differences at p < 0.05. Full article ">

22 pages, 5997 KiB

Open AccessArticle

Poly(ethylene glycol) Methyl Ether Acrylate-Grafted Chitosan-Based Micro- and Nanoparticles as a Drug Delivery System for Antibiotics

by Corina-Lenuța Logigan, Christelle Delaite, Marcel Popa, Elena Simona Băcăiță, Crina Elena Tiron, Cristian Peptu and Cătălina Anișoara Peptu

Polymers 2024, 16(1), 144; https://doi.org/10.3390/polym16010144 - 2 Jan 2024

Cited by 3 | Viewed by 1796

Abstract

Nanotechnology is the science of creating materials at the nanoscale by using various devices, structures, and systems that are often inspired by nature. Micro- and nanoparticles (MPs, NPs) are examples of such materials that have unique properties and can be used as carriers [...] Read more.

Nanotechnology is the science of creating materials at the nanoscale by using various devices, structures, and systems that are often inspired by nature. Micro- and nanoparticles (MPs, NPs) are examples of such materials that have unique properties and can be used as carriers for delivering drugs for different biomedical applications. Chitosan (CS) is a natural polysaccharide that has been widely studied, but it has a problem with low water solubility at neutral or basic pH, which limits its processability. The goal of this work was to use a chemically modified CS with poly(ethylene glycol) methyl ether acrylate (PEGA) to prepare CS micronic and submicronic particles (MPs/NPs) that can deliver different types of antibiotics, respectively, levofloxacin (LEV) and Ciprofloxacin (CIP). The particle preparation procedure employed a double crosslinking method, ionic followed by a covalent, in a water/oil emulsion. The studied process parameters were the precursor concentration, stirring speeds, and amount of ionic crosslinking agent. MPs/NPs were characterized by FT-IR, SEM, light scattering granulometry, and Zeta potential. MPs/NPs were also tested for their water uptake capacity in acidic and neutral pH conditions, and the results showed that they had a pH-dependent behavior. The MPs/NPs were then used to encapsulate two separate drugs, LEV and CIP, and they showed excellent drug loading and release capacity. The MPs/NPs were also found to be safe for cells and blood, which demonstrated their potential as suitable drug delivery systems for biomedical applications. Full article

(This article belongs to the Section Polymer Networks)

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18 pages, 8634 KiB

Open AccessArticle

Chemical Recycling of CFRP in an Environmentally Friendly Approach

by Asuka Sakai, Winarto Kurniawan and Masatoshi Kubouchi

Polymers 2024, 16(1), 143; https://doi.org/10.3390/polym16010143 - 2 Jan 2024

Cited by 1 | Viewed by 1613

Abstract

A novel and environmentally friendly recycling approach for carbon-fiber-reinforced plastics (CFRP) was studied using not only nitric acid (HNO₃) but also our chosen alkaline, sodium hydrogen carbonate (NaHCO₃). The CFRP specimen was first immersed into 8 M HNO₃ [...] Read more.

A novel and environmentally friendly recycling approach for carbon-fiber-reinforced plastics (CFRP) was studied using not only nitric acid (HNO₃) but also our chosen alkaline, sodium hydrogen carbonate (NaHCO₃). The CFRP specimen was first immersed into 8 M HNO₃ at 80 °C for 8 h, and then into 0.1 M NaHCO₃ at 80 °C for 15 min to obtain resin-free recycled carbon fiber (rCFs). Using this new recycling method, it was shown that the recycling time was reduced to 8.3 h, whereas it originally took 24 h, as reported previously. It was shown that immersing the CFRP specimen into NaHCO₃ caused a transesterification reaction with the remaining resin residue on the CF surface, which led to dissolving the resin into the NaHCO₃ aqueous solution all at once. Additionally, NaHCO₃ produced carbon dioxide gas while reacting with the resin residue; the CO₂ gas physically helped removing the resin from the CF’s surface. Moreover, evaluating the physical properties of the rCFs demonstrated an improvement in fiber strength and adhesiveness to resin. Therefore, this recycling method was shown to be effective in recovering high-quality rCFs in a relatively short recycling period. Full article

(This article belongs to the Section Polymer Composites and Nanocomposites)

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16 pages, 3656 KiB

Open AccessArticle

Improving the Sustainability of Catalytic Glycolysis of Complex PET Waste through Bio-Solvolysis

by Izotz Amundarain, Sheila López-Montenegro, Laura Fulgencio-Medrano, Jon Leivar, Ana Iruskieta, Asier Asueta, Rafael Miguel-Fernández, Sixto Arnaiz and Beñat Pereda-Ayo

Polymers 2024, 16(1), 142; https://doi.org/10.3390/polym16010142 - 2 Jan 2024

Cited by 7 | Viewed by 2983

Abstract

This work addresses a novel bio-solvolysis process for the treatment of complex poly(ethylene terephthalate) (PET) waste using a biobased monoethylene glycol (BioMEG) as a depolymerization agent in order to achieve a more sustainable chemical recycling process. Five difficult-to-recycle PET waste streams, including multilayer [...] Read more.

This work addresses a novel bio-solvolysis process for the treatment of complex poly(ethylene terephthalate) (PET) waste using a biobased monoethylene glycol (BioMEG) as a depolymerization agent in order to achieve a more sustainable chemical recycling process. Five difficult-to-recycle PET waste streams, including multilayer trays, coloured bottles and postconsumer textiles, were selected for the study. After characterization and conditioning of the samples, an evaluation of the proposed bio-solvolysis process was carried out by monitoring the reaction over time to determine the degree of PET conversion (91.3–97.1%) and bis(2-hydroxyethyl) terephthalate (BHET) monomer yield (71.5–76.3%). A monomer purification process, using activated carbon (AC), was also developed to remove the colour and to reduce the metal content of the solid. By applying this purification strategy, the whiteness (L*) of the BHET greatly increased from around 60 to over 95 (L* = 100 for pure white) and the Zn content was significantly reduced from around 200 to 2 mg/kg. The chemical structure of the purified monomers was analyzed via infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC), and the composition of the samples was measured by proton nuclear magnetic resonance (¹H-NMR), proving a high purity of the monomers with a BHET content up to 99.5% in mol. Full article

(This article belongs to the Section Biobased and Biodegradable Polymers)

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50 pages, 7061 KiB

Open AccessReview

Fresh Properties, Strength, and Durability of Fiber-Reinforced Geopolymer and Conventional Concrete: A Review

by Osama Mohamed and Haya Zuaiter

Polymers 2024, 16(1), 141; https://doi.org/10.3390/polym16010141 - 1 Jan 2024

Cited by 10 | Viewed by 5308

Abstract

Reducing the environmental footprint of the construction industry in general and concrete in particular is essential. The addition of synthetic and natural fibers to concrete mixes at appropriate dosages enhances durability and strength and extends the lifespan of concrete infrastructures. This study reviews [...] Read more.

Reducing the environmental footprint of the construction industry in general and concrete in particular is essential. The addition of synthetic and natural fibers to concrete mixes at appropriate dosages enhances durability and strength and extends the lifespan of concrete infrastructures. This study reviews the geometric and mechanical properties of selected fibers such as steel, basalt, polypropylene, polyvinyl alcohol, polyethylene, glass, carbon, and natural fibers and their impact on concrete fresh, mechanical, and durability properties when combined in different configurations. The study focuses on the effect of blending fibers with concrete mixes that use alkali-activated binders based on recycled industrial byproducts such as slag and fly ash and thereby contribute to reduction of CO₂ contribution through complete or partial replacement of Ordinary Portland cement (OPC). As a result, the effect of binder content, binder composition, alkaline activator concentration, and water-to-binder (w/b) ratio on fresh properties, mechanical strength, and durability of concrete with blended fibers is also evaluated in this study. The properties of fiber-reinforced concrete with alkali-activated binder and conventional OPC binders are compared. Fiber-reinforced concrete with alkali-activated binders that are based on industrial byproducts may represent sustainable alternatives to conventional concrete and offers competitive fresh and mechanical properties when fiber properties, fiber content, w/b ratio, binder type, and dosage are carefully considered in concrete mix design. Full article

(This article belongs to the Special Issue Fiber and Polymer Composites: Processing, Simulation, Properties and Applications II)

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28 pages, 12285 KiB

Open AccessArticle

A Novel Recyclable Magnetic Nano-Catalyst for Fenton-Photodegradation of Methyl Orange and Imidazole Derivatives Catalytic Synthesis

by Marzough A. Albalawi, Amira K. Hajri, Bassem Jamoussi and Omnia A. Albalawi

Polymers 2024, 16(1), 140; https://doi.org/10.3390/polym16010140 - 1 Jan 2024

Cited by 3 | Viewed by 1463

Abstract

A magnetite chlorodeoxycellulose/ferroferric oxide (CDC@Fe₃O₄) heterogeneous photocatalyst was synthesised via treated and modified cotton in two steps. The designed nanocomposites were characterised by FTIR, TGA, XRD, SEM, and VSM analyses. The Fenton-photocatalytic decomposition efficiency of the synthesised magnetic catalyst [...] Read more.

A magnetite chlorodeoxycellulose/ferroferric oxide (CDC@Fe₃O₄) heterogeneous photocatalyst was synthesised via treated and modified cotton in two steps. The designed nanocomposites were characterised by FTIR, TGA, XRD, SEM, and VSM analyses. The Fenton-photocatalytic decomposition efficiency of the synthesised magnetic catalyst was evaluated under visible sunlight using Methyl Orange (MO) as a model organic pollutant. The impacts of several degradation parameters, including the light source, catalyst load, irradiation temperature, oxidant dose, and pH of the dye aqueous solution and its corresponding concentration on the Fenton photodegradation performance, were methodically investigated. The (CDC@Fe₃O₄) heterogeneous catalyst showed a remarkable MO removal rate of 97.9% at 10 min under visible-light irradiation. (CDC@Fe₃O₄) nanomaterials were also used in a heterogeneous catalytic optimised protocol for a multicomponent reaction procedure to obtain nine tetra-substituted imidazole derivatives. The green protocol afforded imidazole derivatives in 30 min with good yields (91–97%) at room temperature and under ultrasound irradiation. Generally, a synthesised recyclable heterogeneous nano-catalyst is a good example and is suitable for wastewater treatment and organic synthesis. Full article

(This article belongs to the Special Issue Advanced Composite Materials for Water Contaminant Removal)

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16 pages, 3516 KiB

Open AccessArticle

Thermosensitive Chitosan Hydrogels: A Potential Strategy for Prolonged Iron Dextran Parenteral Supplementation

by Emerson Durán, Andrónico Neira-Carrillo, Felipe Oyarzun-Ampuero and Carolina Valenzuela

Polymers 2024, 16(1), 139; https://doi.org/10.3390/polym16010139 - 31 Dec 2023

Viewed by 1258

Abstract

Iron deficiency anemia (IDA) presents a global health challenge, impacting crucial development stages in humans and other mammals. Pigs, having physiological and metabolic similarities with humans, are a valuable model for studying and preventing anemia. Commonly, a commercial iron dextran formulation (CIDF) with [...] Read more.

Iron deficiency anemia (IDA) presents a global health challenge, impacting crucial development stages in humans and other mammals. Pigs, having physiological and metabolic similarities with humans, are a valuable model for studying and preventing anemia. Commonly, a commercial iron dextran formulation (CIDF) with iron dextran particles (IDPs) is intramuscularly administered for IDA prevention in pigs, yet its rapid metabolism limits preventive efficacy. This study aimed to develop and evaluate chitosan thermosensitive hydrogels (CTHs) as a novel parenteral iron supplementation strategy, promoting IDPs’ prolonged release and mitigating their rapid metabolism. These CTHs, loaded with IDPs (0.1, 0.2, and 0.4 g of theoretical iron/g of chitosan), were characterized for IM iron supplementation. Exhibiting thermosensitivity, these formulations facilitated IM injection at ~4 °C, and its significant increasing viscosity at 25–37 °C physically entrapped the IDPs within the chitosan’s hydrophobic gel without chemical bonding. In vitro studies showed CIDF released all the iron in 6 h, while CTH0.4 had a 40% release in 72 h, mainly through Fickian diffusion. The controlled release of CTHs was attributed to the physical entrapment of IDPs within the CTHs’ gel, which acts as a diffusion barrier. CTHs would be an effective hydrogel prototype for prolonged-release parenteral iron supplementation. Full article

(This article belongs to the Special Issue Research Progress on Chitosan Applications)

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Macroscopic appearance (a) and electron microscopy images (b) of the thermosensitive chitosan/iron dextran hydrogel formulations (CTHs) with increasing iron concentrations (0.1, 0.2, and 0.4 g of theoretical iron/g of chitosan). Full article ">Figure 2
Macroscopic appearance of the chitosan thermosensitive hydrogel (CTH) formulations with increasing iron concentrations (0.1, 0.2, and 0.4 g of theoretical iron/g of chitosan) and the commercial iron dextran formulation (CIDF), showing the separation of the sol–gel phases at 37 °C before (a) and after (b) centrifugation. The white and black arrows indicate the upper (water) phase and the lower (gel) phase of CTH0, respectively; (c,d) show the appearance of CIDF and CTH0.4 injected at 37 °C into a piece of pork meat, respectively. Full article ">Figure 3
Spectrograms of the chitosan thermosensitive hydrogel (CTH) formulations with increasing iron concentrations (0.1, 0.2, and 0.4 g of theoretical iron/g of chitosan), the commercial iron dextran formulation (CIDF), and precursors. Dotted lines mark the main absorption bands. Data obtained through infrared spectroscopy. Full article ">Figure 4
Cumulative iron release from commercial iron dextran formulation (CIDF) and the chitosan thermosensitive hydrogel containing iron dextran particles (CTH0.4) at 37 °C. * Significative differences between formulation values for each measurement time (p < 0.05). Full article ">Figure 5
Two-dimensional schematic representation of interactions among chitosan, glycerophosphate (GP), water, and the iron dextran particles (IDPs) in a chitosan thermosensitive hydrogel in sol state (a) and gel state (b). Dotted circles represent chitosan–GP ionic bonds, and yellow areas represent interactions involving GP–water, chitosan–chitosan, and water–IDP hydrogen bonding. Full article ">

17 pages, 2941 KiB

Open AccessArticle

Inhibition of Pro-Fibrotic Molecules Expression in Idiopathic Pulmonary Fibrosis—Derived Lung Fibroblasts by Lactose-Modified Hyaluronic Acid Compounds

by Alice Donato, Antonino Di Stefano, Nadia Freato, Laura Bertocchi and Paola Brun

Polymers 2024, 16(1), 138; https://doi.org/10.3390/polym16010138 - 31 Dec 2023

Cited by 2 | Viewed by 1495

Abstract

Idiopathic pulmonary fibrosis (IPF) is a chronic inflammatory and fibrotic pathological condition with undefined effective therapies and a poor prognosis, partly due to the lack of specific and effective therapies. Galectin 3 (Gal-3), a pro-fibrotic ß-galactoside binding lectin, was upregulated in the early [...] Read more.

Idiopathic pulmonary fibrosis (IPF) is a chronic inflammatory and fibrotic pathological condition with undefined effective therapies and a poor prognosis, partly due to the lack of specific and effective therapies. Galectin 3 (Gal-3), a pro-fibrotic ß-galactoside binding lectin, was upregulated in the early stages of the pathology, suggesting that it may be considered a marker of active fibrosis. In the present in vitro study, we use Hylach^®, a lactose-modified hyaluronic acid able to bind Gal-3, to prevent the activation of lung myofibroblast and the consequent excessive ECM protein cell expression. Primary human pulmonary fibroblasts obtained from normal and IPF subjects activated with TGF-β were used, and changes in cell viability, fibrotic components, and pro-inflammatory mediator expression at both gene and protein levels were analyzed. Hylach compounds with a lactosylation degree of about 10% and 30% (Hylach1 and Hylach 2), administrated to TGF-β—stimulated lung fibroblast cultures, significantly downregulated α-smooth muscle actin (α-SMA) gene expression and decreased collagen type I, collagen type III, elastin, fibronectin gene and protein expression to near baseline values. This anti-fibrotic activity is accompanied by a strong anti-inflammatory effect and by a downregulation of the gene expression of Smad2 for both Hylachs in comparison to the native HA. In conclusion, the Gal-3 binding molecules Hylachs attenuated inflammation and TGF-β—induced over-expression of α-SMA and ECM protein expression by primary human lung fibroblasts, providing a new direction for the treatment of pulmonary fibrotic diseases. Full article

(This article belongs to the Special Issue Biopolymer for Biomedical Application)

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Hylach® molecular structure. Full article ">Figure 2
Expression of α-SMA and ECM molecules by lung fibroblast from healthy (a) and IPF donors (b) cultures exposed to 5 ng/mL TGF-β for 24 h. Quantification of RNA transcript levels was carried out using qPCR analyses. The data represent the mean ± standard error (SE) of results obtained from three independent experiments. Statistical differences were assessed using an unpaired Student’s t-test, and significance levels were indicated as follows: * p < 0.05, ** p < 0.01, *** p < 0.001, and **** p < 0.0001. Full article ">Figure 3
Time-dependent impact of HA and Hylach on human lung fibroblast viability. 1200 cells from both healthy (a) and IPF (b) subjects were seeded in 96-well culture plates and treated with 0.5 mg/mL HA, Hylach 1, and Hylach 2 for 1, 3, and 6 days. Cell viability was measured using an MTT assay. Data are presented as the means ± standard error (SE) from three independent experiments. Statistical variances were assessed utilizing the unpaired Student’s t-test. The percentage of lactose derivative residues is as follows: Hylach 1 = 10%, Hylach 2 = 30%. Full article ">Figure 4
Modulation of α-Smooth Muscle Actin (α-SMA) gene expression in lung fibroblasts by Hylach and native HA. Human pulmonary fibroblasts from healthy (a) and IPF 8 (b) donors were exposed to TGF-β (5 ng/mL) for 24 h and subsequently cultured in the presence or absence of HA, Hylach 1, and Hylach 2. qPCR was employed to measure the mRNA level for α-SMA at 4, 10, and 24 h post-treatment. Statistical significance was determined via a one-way ANOVA test with multiple comparisons vs. untreated cells (* p < 0.05, *** p < 0.001, and **** p < 0.0001). The results represent the mean ± standard error (SE) of three independent experiments. Percentage of lactose derivative residues: Hylach 1 = 10%, Hylach 2 = 30%. Full article ">Figure 5
ECM protein expression by TGF-β stimulated fibroblasts treated with HA and Hylach. Human pulmonary fibroblasts from control (a) and IPF (b) donors were exposed to TGF-β (5 ng/mL) for 24 h and then cultured in the presence or absence of HA, Hylach 1 or Hylach 2. mRNA levels for collagen I, collagen III, elastin, fibronectin, and TGF-β were analyzed using qPCR at 4, 10, and 24 h post-treatment. Statistical significance was determined via a one-way ANOVA test with multiple comparisons vs. untreated cells (* p < 0.05, ** p < 0.01, *** p < 0.001, and **** p < 0.0001). The results represent the mean ± standard error (SE) of three independent experiments. Percentage of lactose derivative residues: Hylach 1 = 10%, Hylach 2 = 30%. Full article ">Figure 5 Cont.
ECM protein expression by TGF-β stimulated fibroblasts treated with HA and Hylach. Human pulmonary fibroblasts from control (a) and IPF (b) donors were exposed to TGF-β (5 ng/mL) for 24 h and then cultured in the presence or absence of HA, Hylach 1 or Hylach 2. mRNA levels for collagen I, collagen III, elastin, fibronectin, and TGF-β were analyzed using qPCR at 4, 10, and 24 h post-treatment. Statistical significance was determined via a one-way ANOVA test with multiple comparisons vs. untreated cells (* p < 0.05, ** p < 0.01, *** p < 0.001, and **** p < 0.0001). The results represent the mean ± standard error (SE) of three independent experiments. Percentage of lactose derivative residues: Hylach 1 = 10%, Hylach 2 = 30%. Full article ">Figure 6
Pro-inflammatory molecule gene expression in primary lung fibroblasts following exposure to U937 CM in the presence or absence of Hylach compounds and native HA. Primary human lung fibroblasts isolated from control and IPF donors were cultivated in the presence or absence of 0.5 mg/mL HA, Hylach 1, and Hylach 2 compounds after a 24 h exposure to activated U937 CM. At 4 and 10 h after the treatment, the gene expression of IL-1β, TNF-α, TGF-β, and Gal-3 was analyzed using qPCR. Statistical significance was determined via a one-way ANOVA test with multiple comparisons vs. untreated cells (* p < 0.05, ** p < 0.01, *** p < 0.001, and **** p< 0.0001). The results represent the mean ± standard error (SE) of three independent experiments. Percentage of lactose derivative residues: Hylach 1 = 10%, Hylach 2 = 30%. Full article ">Figure 7
Smad-2 expression of primary human lung fibroblasts exposed to TGF-β in the presence or absence of Hylach and HA molecules. Cell cultures were exposed for 24 h to TGF-β and then cultured in the presence or absence of 0,5 mg/mL of Hylach or HA. RNA transcript levels for Smad-2 were assessed using qPCR at 4, 10, and 24 h post-treatment. Statistical differences were determined using the ANOVA test with multiple comparisons vs. untreated cells (* p < 0.05, ** p < 0.01 and *** p <0.001), and data are presented as mean ± SE obtained from three independent experiments. Percentage of lactose derivative residues: Hylach 1 = 10%, Hylach 2 = 30%. Full article ">

16 pages, 3665 KiB

Open AccessArticle

Development of an Innovative Lightweight Composite Material with Thermal Insulation Properties Based on Cardoon and Polyurethane

by Raquel A. Fernandes, Nuno Ferreira, Sandro Lopes, Jorge Santos, Nelson Bento Pereira, Nuno Oliveira Ferreira, Lina Nunes, Jorge M. Martins and Luisa H. Carvalho

Polymers 2024, 16(1), 137; https://doi.org/10.3390/polym16010137 - 31 Dec 2023

Viewed by 1479

Abstract

The search for innovative and sustainable solutions to improve the energy efficiency of the construction industry has been a hot topic for researchers due to the tremendous impact of insulator materials in the thermal comfort of buildings. In the present work, an innovative [...] Read more.

The search for innovative and sustainable solutions to improve the energy efficiency of the construction industry has been a hot topic for researchers due to the tremendous impact of insulator materials in the thermal comfort of buildings. In the present work, an innovative lightweight composite material with thermal insulation properties was developed, for the first time, by using cardoon particles and polyurethane. The formulation of the composite material was optimized in terms of cardoon fraction and the polyol/isocyanate ratio, to achieve the best compromise between internal bond (IB) strength and thickness swelling (TS). The best performing composite was PU75-CP45, with 45 wt% of cardoon particles and 75% of isocyanate, achieving an IB of 0.41 MPa and a TS of 5.3%. Regarding insulation properties, the PU75-CP45 composite material exhibits a promising performance when compared to conventional construction industry materials by tuning its thickness. Additionally, the composite material presented very low emissions of volatile organic compounds and formaldehyde (bellow to legislation levels) and high resistance to biological degradation. Full article

(This article belongs to the Special Issue Fibre-Reinforced Polymeric Composites)

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24 pages, 11647 KiB

Open AccessArticle

Catalytic Ring-Opening Polymerisation of Cyclic Ethylene Carbonate: Importance of Elementary Steps for Determining Polymer Properties Revealed via DFT-MTD Simulations Validated Using Kinetic Measurements

by Daniel Brüggemann, Martin R. Machat, Reinhard Schomäcker and Mojgan Heshmat

Polymers 2024, 16(1), 136; https://doi.org/10.3390/polym16010136 - 31 Dec 2023

Cited by 1 | Viewed by 2039

Abstract

The production of CO₂-containing polymers is still very demanding in terms of controlling the synthesis of products with pre-defined CO₂ content and molecular weight. An elegant way of synthesising these polymers is via CO₂-containing building blocks, such as [...] Read more.

The production of CO₂-containing polymers is still very demanding in terms of controlling the synthesis of products with pre-defined CO₂ content and molecular weight. An elegant way of synthesising these polymers is via CO₂-containing building blocks, such as cyclic ethylene carbonate (cEC), via catalytic ring-opening polymerisation. However, to date, the mechanism of this reaction and control parameters have not been elucidated. In this work, using DFT-metadynamics simulations for exploiting the potential of the polymerisation process, we aim to shed more light on the mechanisms of the interaction between catalysts (in particular, the catalysts K₃VO₄, K₃PO₄, and Na₂SnO₃) and the cEC monomer in the propagation step of the polymeric chain and the occurring CO₂ release. Confirming the simulation results via subsequent kinetics measurements indicates that, depending on the catalyst’s characteristics, it can be attached reversibly to the polymeric chain during polymerisation, resulting in a defined lifetime of the activated polymer chain. The second anionic oxygen of the catalyst can promote the catalyst’s transfer to another electrophilic cEC monomer, terminating the growth of the first chain and initiating the propagation of the new polymer chain. This transfer reaction is an essential step in controlling the molecular weight of the products. Full article

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