- Tuskegee University, Materials Science and Engineering, Faculty Memberadd
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Woven fabric composites are increasingly being used in composite structures for applications in the aircraft, marine, and automotive industries. With emerging low-cost processing techniques for composite materials, the role of fabric... more
Woven fabric composites are increasingly being used in composite structures for applications in the aircraft, marine, and automotive industries. With emerging low-cost processing techniques for composite materials, the role of fabric architectures in sustaining low, intermediate, and high velocity impact loads is a subject of interest. An example of a low-cost process is the out-of-autoclave, vacuum assisted resin transfer molding (VARTM) technique. The present study evaluates the intermediate velocity impact response of two commonly used structural carbon fabric laminates produced from plain and 2/2 twill woven fabrics, processed using VARTM. A series of impact tests have been performed on the all plain, all twill and hybrid plain-twill weave carbon/epoxy laminates. All laminates studied were covered with a polycarbonate facing in order to enhance the impact resistance of the carbon/epoxy laminates. The perforation mechanism, ballistic limit, and damage evolution of each laminate h...
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Properties of cellulose-derived fibers are extremely sensitive to surface treatment. Many studies have investigated the effects of varying surface treatment parameters in natural fibers to improve fiber-matrix bonding; however, work is... more
Properties of cellulose-derived fibers are extremely sensitive to surface treatment. Many studies have investigated the effects of varying surface treatment parameters in natural fibers to improve fiber-matrix bonding; however, work is still needed to assist with developing better quality control methods to use these fibers in more load-bearing composites. Kenaf fibers were alkali treated, and the surface and morphology were analyzed to determine how treatment time affected the bonding sites in natural fibers. The mechanical behavior was also characterized, and tensile testing reported a 61% increase in strength and a 25% increase in modulus in fibers treated for 16 hours. The increase in tensile properties was assumed to result from increased intermolecular interaction and increased crystallinity in cellulose, which was supported by XRD. On the other hand, FTIR spectroscopy and XPS showed that the amount of hydroxyl groups needed for fiber-matrix bonding decreased at longer treatme...
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Research Interests: Engineering, Materials Engineering, Mechanical Engineering, Scanning Electron Microscopy, Nanocomposites, and 13 moreThermoforming, Composite Material, Injection Molding, Composite structures, Weight, Composite Sandwich Panel, Scanning Electron Microscope, Epoxy Resin, Brittle Fracture, Impact Test, Failure Mode, Resin Transfer Molding, and Failure Modes
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Research Interests: Engineering, CHEMICAL SCIENCES, Biofuel and Bio Ethanol Production from Biomass, Nanocrystalline Cellulose, Utlization of Food and Agricultural Wastes, and 7 moreMFC (Microfibrillated Cellulose), Biomass Processing, Journal of Applied Polymer Science, Cellulose Modification, Ball Milling, Cellulose nanocrystals, and Cellulose microfibrils
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With the depletion of petrochemical resources, the increase in greenhouse gases emission, and shrinking landfill capacity, the manufacture, use, and disposal of synthetic composites is at an all-time high. This does not lead to any form... more
With the depletion of petrochemical resources, the increase in greenhouse gases emission, and shrinking landfill capacity, the manufacture, use, and disposal of synthetic composites is at an all-time high. This does not lead to any form of sustainable use of composites, let alone allow for growth of the use and supporting industry. Many researchers and industry partners understand the need for sustainable composites and have renewed the research and funding for such progress. One of the particular areas is the expansion into nitroxide mediated polymerization due to the reduction in uncontrolled exothermic reactions during the curing process of thick components. This allows larger and thicker natural composites to be fabricated with a lower cure temperature. The research has expanded from initial work involving the polymerization using a nitroxyl mixed with a conventional initiator like dibenzoyl peroxide [2, p. 422] to chain end functionalization [3], through the development of well...
The prime objective of this study was to fabricate epoxy polymer composite modified with graphene nanoplatelets (GP) and montmorillonite nanoclay (MMT) binary filler materials. Different loading percentages of individual and binary... more
The prime objective of this study was to fabricate epoxy polymer composite modified with graphene nanoplatelets (GP) and montmorillonite nanoclay (MMT) binary filler materials. Different loading percentages of individual and binary nanofillers were incorporated into an epoxy matrix system to investigate the synergistic effect of nanofillers on composites properties. Dynamic mechanical analysis (DMA) and three point bend test were carried out to investigate the viscoelastic and flexural properties of neat epoxy and nanofillers reinforced nanocomposites. Incorporation of 3 wt. % of MMT and 0.1 wt. % of GP resulted in better flexure strength, modulus and storage modulus although there is no significance change in glass transition temperature (Tg).
Research Interests: Materials Science, Polymer Chemistry, Composite Materials and Structures, Composites, Graphene, and 12 moreNanocomposites, Nanomaterials, Composite Materials, Nanotechnology, Advanced Materials, Polymer Nanocomposites, Polymer Composites, Nanoscience, Applications of Graphene, polymer science and Engineering, Layered nanoclay composites, and Nanoclay
The objective of this work was to investigate the mitigating effects of montmorillonite nanoclay (MMT) if any, on the properties of carbon fiber reinforced composites (CFRC) infused with different weight percentages of MMT and exposed to... more
The objective of this work was to investigate the mitigating effects of montmorillonite nanoclay (MMT) if any, on the properties of carbon fiber reinforced composites (CFRC) infused with different weight percentages of MMT and exposed to UV radiation and condensation. Composites used in this study were control and with 1-3 wt. % of nanoclay. Samples were exposed to 15 days of continuous UV radiation and condensation using QUV/SE accelerated weathering system. Mechanical and thermal properties were characterized by compression tests, thermo-gravimetric analysis (TGA) and dynamic mechanical analyses (DMA) according to ASTM standards. Surface morphology of exposed samples was characterized through Scanning electron microscopy (SEM). These properties were characterized every 120 hours of exposure. Samples exposed to condensation did not follow any specific pattern, although there was a decrease in mechanical properties in all samples.
The objective of this work was to find out the compositional characteristics of wheat straw in terms of cellulose and lignin contents and assess the suitability of wheat straw for isolation of cellulose microfibrils. The fractionation... more
The objective of this work was to find out the compositional characteristics of wheat straw in terms of cellulose and lignin contents and assess the suitability of wheat straw for isolation of cellulose microfibrils. The fractionation process includes formic acid/peroxyformic acid treatment, bleaching and ball milling of bleached cellulose. 39.10 % Cellulose, 20.40 % lignin and 25.02 % of other compounds were extracted. Extracted cellulose was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron micrograph (SEM), and thermogravimetric analysis (TGA). Morphological and thermal analyses studies showed that the extracted microfibrils had reduced length and diameter and showed good thermal stability suitable for various advanced nano technological applications.
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Diglycidyl ether of Bisphenol A (DGEBA) based SC-15 epoxy resin was modified with three different commercially available montmorillonite (MMT) nanoclay: Nanomer I.28E and Cloisite 10A and 30B. Cure behavior of nanocomposites was studied... more
Diglycidyl ether of Bisphenol A (DGEBA) based SC-15 epoxy resin was modified with three different commercially available montmorillonite (MMT) nanoclay: Nanomer I.28E and Cloisite 10A and 30B. Cure behavior of nanocomposites was studied using a variety of techniques. Primary focus of this study was to investigate influence of different surface modifications of MMT nanoclay on rheological properties and cure behavior of SC-15 epoxy resin. By adding MMT to SC-15 epoxy resin, chemistry of the epoxy is altered leading to changes in rheological properties and ultimately enthalpy and activation energy of reactions. Addition of Nanomer I.28E delayed gelation, while Cloisite 10A and 30B accelerated gelation, regardless of the curing temperature. Activation energy of reaction was lower with the addition of Nanomer I.28E and Cloisite 10A and higher for Cloisite 30B compared to neat SC-15 epoxy composite.
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In this study, sonication dispersion technique was employed to infuse 0.1–0.4 wt.% carbon nanofibers (CNFs) into polyester matrix to enhance thermomechanical properties of resulting nanocomposites. The effect of dispersion conditions has... more
In this study, sonication dispersion technique was employed to infuse 0.1–0.4 wt.% carbon nanofibers (CNFs) into polyester matrix to enhance thermomechanical properties of resulting nanocomposites. The effect of dispersion conditions has been investigated with regard to the CNF content and the sonication time. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) micrographs revealed excellent dispersion of 0.2 wt.% CNF infused in polyester, resulting in enhanced mechanical responses. Polyester with 0.2 wt.% CNF samples resulted in 88% and 16% increase in flexural strength and modulus, respectively, over the neat one. Quasi-static compression tests showed similar increasing trend with addition of CNF. Fracture morphology study of tested samples revealed relatively rougher surface in CNF-loaded polyester compared to the neat due to better interaction between the fiber and the matrix. Dynamic mechanical analysis (DMA) study exhibited about 35% increase in the storage...
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ABSTRACTCarbon fiber-reinforced epoxy composites (CFEC) were fabricated infusing 0, 0.15, 0.30, and 0.40 wt% amino-functionalized XD-grade carbon nanotubes (NH2-XDCNTs) using the compression molding process under 16 kips. The... more
ABSTRACTCarbon fiber-reinforced epoxy composites (CFEC) were fabricated infusing 0, 0.15, 0.30, and 0.40 wt% amino-functionalized XD-grade carbon nanotubes (NH2-XDCNTs) using the compression molding process under 16 kips. The thermo-mechanical and interlaminar shear properties of CNT incorporated carbon/epoxy composite samples were evaluated by performing dynamic-mechanical thermal analysis (DMTA) and short beam shear (SBS) tests. XD-CNTs were infused into Epon 862 resin using a mechanical stirrer followed by a high intensity ultrasonic liquid processor for better dispersion. After the sonication, the mixture was placed in a three roll milling processor for 3 successive cycles at 140 rpm, with the gap spaces incrementally reduced from 20 to 5 μm, to obtain the uniform dispersion of CNTs throughout the resin. Epikure W curing agent was then added to the modified resin and mixed using a high-speed mechanical stirrer. Finally, the fiber was reinforced with that modified resin using the...