Chemical Engineering

A novel polymer host from carboxymethyl cellulose (CMC)/poly(N-isopropylacrylamide) (PNiPAM) was developed for a high safety solid polymer electrolyte (SPE) in a zinc ion battery. Effects of the PNiPAM loading level in the range of 0–40% by weight ( wt%) on the chemical, mechanical, thermal, and morphological properties of the CMC/PNiPAMx films (where x is the wt% of PNiPAM) were symmetrically investigated. The obtained CMC/PNiPAMx films showed a high compatibility between the polymers. The CMC/PNiPAM20 blend showed the greatest tensile strength and modulus at 37.9 MPa and 2.1 GPa, respectively. Moreover, the thermal degradation of CMC was retarded by the addition of PNiPAM. Scanning electron microscopy images of CMC/PNiPAM20 revealed a porous structure that likely supported Zn2+ movement in the SPEs containing zinc triflate, resulting in the high Zn2+ ion transference number (0.56) and ionic conductivity (1.68 × 10–4 S cm−1). Interestingly, the presence of PNiPAM in the CMC/PNiPAMx...

In this study, electrospinning technique was used for ternary system to fabricate nanofiber mats from silk fibroin (SF):gelatin (G):chitosan (C) with various mass ratios i.e. 10:20:0, 10:20:0.5, 10:20:1, 10:20:1.5, 10:20:2, and 20:10:1. An increase in chitosan content of the mats was found to decrease average fiber diameter and with narrow size distribution. Tensile strength of SF:G:C nanofiber having greater SF content was lower than that of the fiber mat having lower SF content. The obtained fiber mats were then crosslinked by three different crosslinking agents including ethanol, glutaraldehyde and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC)/N-hydroxysuccinmide (NHS). The smooth fiber with high porosity of the nanofiber mat was observed after crosslinked using EDC/NHS agent. A less swollen fiber was noticed in the fiber mats having higher SF content. The results from in vitro study revealed the good cell adhesion and proliferation of gingival tissues. Such ...

Energy absorptions under ballistic impacts of aramid fiber-reinforced poly(benzoxazine-co-urethane) composites at urethane mass concentrations of 0, 10, 20, 30, and 40 wt.% were investigated. The energy absorption of the composite was investigated by subjecting eight plies of the specimen with 9 mm and .44 Magnum according to levels II and IIIA of the National Institute of Justice standard-0101.04. The composite having the urethane mass concentration of 20 wt.% exhibited the synergistic behavior in energy absorption at both levels II and IIIA. The 20 wt.% of PU composite also possessed the greatest tensile strength and modulus. The numerical prediction revealed that the ballistic limit of aramid fiber-reinforced poly(benzoxazine-co-urethane) ballistic panel was as high as 690 m s−1. High energy absorption capabilities of the composites can be tailored for fabricating the ballistic panels in soft armor applications.

The bioactive packaging polyvinyl alcohol PVA/starch (PSt) films were prepared by incorporating green synthesized silver nanoparticles (AgNPs). The effect of oregano essential oil (OEO) content on the green synthesis of AgNPs in PSt film was studied. The PSt-AgNPs containing 5 wt% OEO showed minimum inhibitory concentration against Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ). A synergistic effect on antibacterial activity with PSt incorporated AgNPs and OEO was achieved. The use of OEO content in this work was the lowest when compared to other bioactive containing OEO. The improvements of water resistance were also observed. The tensile strength and tensile modulus of film increased 80.9% and 88.6%, respectively. The releases of silver ion of PSt-AgNPs containing 5 wt% OEO in different foods were 9.31% for deionized water, 7.48% for ethanol and 24.51% for acetic acid. These values were lower than the requirements of European Standard EN 1186-1:2002. The incorporation of green synthesized AgNPs using OEO and PSt thus improved the bioactive nanocomposite film performance for food packaging applications.

This study aims to develop a lightweight ballistic helmet based on nanocomposite with matrix of the copolymer of benzoxazine with an urethane prepolymer [poly(BA-a-co-PU)], at mass ratio 80/20, reinforced with aramid fabric and multi-walled carbon nanotubes (MWCNTs). This has a protection level II according to the National Institute of Justice (NIJ) 0106.01 standard. The effects of MWCNTs mass content in a range of 0 to 2 wt% on tensile, physical and ballistic impact properties of the nanocomposite were investigated. The results revealed that the introduction of MWCNTs enhanced the tensile strength and energy at break of the nanocomposite; the highest values were obtained at 0.25 wt%. In addition, the nanocomposite laminate with 20 plies of aramid fabric showed the lowest back face deformation of 8 mm which was much lower than that specified by the NIJ standard. According to Military Standard (MIL-STD) 662F, the simulation prediction revealed that the ballistic limit of the ballisti...

Zinc ionic conducting-based gel polymer electrolytes (GPEs) were fabricated from carboxymethyl cellulose (CMC) and three different zinc salts in a mass ratio ranging within 0–30 wt%. The effects of zinc salt and loading level on the structure, thermal, mechanical, mechanical stability, and morphological properties, as well as electrochemical properties of the GPEs films, were symmetrically investigated. The mechanical properties and mechanical stability of CMC were improved with the addition of zinc acetate, zinc sulphate, and zinc triflate, approaching the minimum requirement of a solid state membrane for battery. The maximum ionic conductivity of 2.10 mS cm−1 was achieved with the addition of 15 wt% zinc acetate (ZnA), GPEA15. The supported parameters, indicating the presence of the amorphous region that likely supported Zn2+ movement in the CMC chains, were clearly revealed with the increase in the number of mobile Zn2+ carriers in FT-IR spectra and the magnitude of ionic transfe...

Abstract Active packaging containing photocatalyst is generally used to solve the issues of loss and quality deterioration of fresh fruits. However, only ultraviolet (UV) light can activate these photo-catalysts in ethylene photo-degradation. To overcome this limitation, green synthesized silver nanoparticles (AgNPs) that inhibits ethylene gas production under visible light has been developed. In this study, spent green tea was mixed with deionized water at various ratios ranging from liquid to solid to obtain spent green tea extract (ex-SGT) having different concentrations used for synthesis of AgNPs. The results indicated that a good distribution of particles with a bandgap energy of 2.17 eV which was in the visible region for ethylene photo-degradation was successfully obtained with the synthesized AgNPs-60 (ex-SGT at the ratio of 60:1). The coated paper possessed an antibacterial activity and decreased the ethylene concentration in mango’s packaging. Based on the finding in this work, it appears that the coated paper could have potential to be used for novel packaging of fruits to delay their ripening so that their freshness can be maintained.

Eco-friendly smart nanocomposite hydrogels were developed in this study. Green synthesized silver nanoparticles (AgNPs) using extracted sugarcane leaves were incorporated into hydrogel-based polyvinyl alcohol, carboxymethyl cellulose, glycerol, and borax. Different concentrations of silver nitrate at 5, 10, 20, 30, and 50 mM were used to obtain AgNPs (AgNPs-5, AgNPs-10, AgNPs-20, AgNPs-30, and AgNPs-50, respectively). The presence of glycerol and AgNPs in hydrogel improved the long-term stability of hydrogel. Uniform dispersion of AgNPs-30 in the hydrogel provided the highest tensile strength and strain. After the self-healing test, the hydrogel containing AgNPs were found to have tensile properties comparable to those of conductive hydrogels in previous reports. The conductivity values ranged from 0.14 mS/m to 0.22 S/m. The hydrogel containing AgNPs-30 showed the highest gauge factor (GF) of 5.76 at a stretchability of 265%. The hydrogel containing AgNPs with a low-cost and environment-friendly fabrication process could be applied as a strain sensor.

Epoxy is extensively used for anti-corrosion coatings on metallic materials. Conventional epoxy coatings have a permanent crosslink network that is unable to repair itself when cracks and damages occur on the coating layer. This study aims to develop self-healing epoxy vitrimer/carbon nanotube (CNTs) nanocomposite for coating. Two bio-based curing agents viz., cashew nut shell liquid (CNSL) and citric acid (CA) were employed to create covalent adaptable networks. The 0–0.5 wt% CNTs were also incorporated into epoxy/CNSL/CA matrix (V-CNT0-0.5). Based on the results of our study, thermomechanical properties of V-CNT nanocomposites increased with increasing CNTs content. The bond exchange reaction of esterification was thermally activated by near infrared (NIR) light. The V-CNT0.5 showed the highest self-healing efficiency in Shore D hardness of 97.34%. The corrosion resistance of coated steel with V-CNT0 and V-CNT0.5 were observed after immersing the samples in 3.5 wt% NaCl for 7 days. The corrosion rate of coated steel with V-CNT0.5 decreased from 9.53 × 102 MPY to 3.12 × 10–5 MPY whereas an increase in protection efficiency of 99.99% was observed. By taking advantages of the superior self-healing and anti-corrosion properties, V-CNT0.5 could prove to be a desirable organic anti-corrosion coating material.