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Das K.,University of Calcutta | Ray D.,University of Calcutta | Bandyopadhyay N.R.,Bengal Engineering and Science University | Gupta A.,University of Calcutta | And 4 more authors.
Industrial and Engineering Chemistry Research | Year: 2010

The effects of incorporating different cross-linking agents into starch/poly(vinyl alcohol) (PVA) blend were examined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), mechanical characterization, dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), moisture absorption tests, and scanning electron microscopy (SEM). Different cross-linkers such as borax, formaldehyde, epichlorohydrin, and ZnO were used to cross-link the films at the same weight percent. The films were prepared by gelatinization followed by a solution casting method. SEM microstructures revealed that the destructuring of starch granules was significantly influenced by the presence of cross-linkers during the gelatinization process. The extent of cross-linking was measured through the determination of the normalized gel mass and the normalized swelling degree of the films in dimethyl sulfoxide (DMSO) solvent. Tensile strength and tensile modulus were highest in borax cross-linked film, while the highest flexibility was achieved with the epichlorohydrin cross-linked film. Damping was remarkably increased, and moisture absorption was considerably decreased in the cross-linked films. The onset of thermal degradation was lowered, but the char yield was slightly increased in the cross-linked films. © 2010 American Chemical Society.

Singh S.,Michigan State University | Mohanty A.K.,Bioproducts Discovery and Development Center | Misra M.,Bioproducts Discovery and Development Center
Composites Part A: Applied Science and Manufacturing | Year: 2010

This investigation deals with the development of hybrid composites from wood fiber, talc and a bioplastic i.e., polyhydroxybutyrate-co-valerate (PHBV) using the extrusion-injection molding. Synergistic improvement in the mechanical properties of PHBV-wood fiber composites were obtained with the additional reinforcement of micro sized talc in it. The compositional design of hybrid green composites primarily focuses to create a balance among the cost effectiveness, the environment friendliness and the characteristics of the hybrid composites. The hybrid green composites showed a pronounced leap of 200% in the Young's and flexural modulus with the dual reinforcement of 20 wt.% talc and 20 wt.% wood fiber in PHBV matrix. The dynamic-mechanical and thermo-mechanical properties of the composite were experimentally determined and show similar trend. The theoretical reasoning based on the surface energy parameters of the interacting components in the composite is elaborated to explain the reinforcing effect of talc and wood fiber. The Morphological analysis of the hybrid composite was carried out using the scanning electron microscopy (SEM), to study the interfacial interactions among the different components in the hybrid composite. The quantitative decrease of 36% in coefficient of linear thermal expansion, and the improvement in heat deflection temperature of the hybrid composite was also observed. This investigation was based on the structure-property-processing, co-relationships of the three components in order to obtain hybrid composites. © 2009 Elsevier Ltd. All rights reserved.

Ozgur Seydibeyoglu M.,Bioproducts Discovery and Development Center | Misra M.,Bioproducts Discovery and Development Center | Misra M.,University of Guelph | Mohanty A.,Bioproducts Discovery and Development Center | Mohanty A.,University of Guelph
International Journal of Plastics Technology | Year: 2010

In this study, the impact strength and elongation properties of a bacterial biopolymer,polyhydroxyutyrate-co-valerate (PHBV) co-polymer were improved with different functionalized vegetable oils, and nano structured Polyhedral Oligomeric Silsesquioxane (POSS). PHBV was blended with functionalized oils, epoxidized linseed oil, epoxidized soybean oil, and epoxy soyate using twin screw melt processing, and samples for testing were prepared by injection molding. PHBV was also blended with POSS and blend of PHBV with and without epoxy soyate were also prepared. The materials were characterized by impact strength testing, tensile testing, dynamic mechanical analysis, differential scanning calorimetry, and scanning electron microscopy studies. The studies showed that the impact strength was improved 92% with the epoxy soyate, which is a chemically modified version of epoxidized soybean oils by reaction with alcohols. The impact strength was further improved (120%) compared to neat PHBV synergistically with the addition of POSS to PHBV-epoxy soyate blend. With the addition of POSS to the PHBV-epoxy soyate system, elongation was improved 105%. It was also observed that with the addition of functionalized oils and POSS, the melting temperature of the PHBV was reduced more than 10°C which is very important for the processing of PHBV. © Central Institute of Plastics Engineering & Technology 2010.

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