MECHANICAL AND THERMAL PROPERTIES OF LOW DENSITY POLYETHYLENE (LDPE) COMPOSITES WITH THERMOPLASTIC STARCH AND STARCH DICARBOXYLIC ACID

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Date
2013-05
Authors
BUKHARI, MUSA MUHAMMAD.
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Abstract
ABSTRACT The Mechanical and thermal properties of low density polyethylene (LDPE) composites with thermoplastic starch and starch dicarboxylic acid have been studied. Thermoplastic starch (TPS) and Starch dicarboxylic acid compound (SDCA) were prepared from potato starch. These modified starches indicated reduced crystallinity and better thermal stability as compared to native starch. The complexation of the plasticizer with the starch also resulted in a shift of the OH and C-H bands on the FT-IR spectra indicating replacement of Hydroxyl bonds between the starch polymer chains with weaker hydrogen bonds between the starch and the plasticizer. The FT-IR spectrum of the starch dicarboxylic acid compound suggested partial ester formation between the starch and the dicarboxylic acid. The SEM micrographs of the TPS showed the broken down of the polygonal shaped granules of the starch to patches of various sizes, but on the SDCA micrograph, the starch granules appeared swollen which could be attributed to the gelatinizing action of the dicarboxylic acid on the starch granules. The modified starch obtained were each melt blended with low density polyethylene to obtain LDPE/TPS and LDPE/SDCA composites. Various investigations suggested immiscibility between the composite components i.e the LDPE (matrix) and the TPS or SDCA as fillers. It was shown that the complexation of the LDPE with the TPS/SDCA has taken place on the amorphous region and therefore the crystalline region is not affected. These composites have slightly better thermal stability as compared to LDPE, but their mechanical properties were not so good. The water absorbency studies indicated that LDPE/SDCA composites are more susceptible to water attack than the LDPE/TPS, similarly the biodegradation studies revealed that the LDPE/SDCA composite are more prone to soil degradation as compared to the LDPE/TPS composites.
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DEPARTMENT OF TEXTILE SCIENCE AND TECHNOLOGY, FACULTY OF SCIENCE, AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA.
Keywords
MECHANICAL,, THERMAL,, PROPERTIES,, LOW,, DENSITY,, POLYETHYLENE,, COMPOSITES,, THERMOPLASTIC,, STARCH,, STARCH,, DICARBOXYLIC,, ACID.
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