THESIS
2000
xiii, 116 leaves : ill. ; 30 cm
Abstract
The amount of plastic waste has increased by about 10% per year for the past 20 years and it has caused a great environmental concern to the public. The large volume to weight ratio of the plastics is a great problem to the landfill capacity. Biodegradation of plastic is potentially the most environmentally friendly plastic waste management practice. Polyhydroxyalkanoates (PHAs) are a prominent group of biodegradable thermoplastics and can serve as an exogenous carbon source for various microbes. In this study, the kinetics of the biodegradation of PHBV and its blends were investigated....[
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The amount of plastic waste has increased by about 10% per year for the past 20 years and it has caused a great environmental concern to the public. The large volume to weight ratio of the plastics is a great problem to the landfill capacity. Biodegradation of plastic is potentially the most environmentally friendly plastic waste management practice. Polyhydroxyalkanoates (PHAs) are a prominent group of biodegradable thermoplastics and can serve as an exogenous carbon source for various microbes. In this study, the kinetics of the biodegradation of PHBV and its blends were investigated.
A kinetic model is developed to describe the PHBV biodegradation rate which is a second-order reaction with respect to the polymer weight and a first-order reaction respect to the biomass weight. The relationship between the biodegradation constant and temperature can be described by the Arrhenius equation. Biodegradation was also enhanced with increase in the extent of agitation. From the morphology of degraded polymers, PHBV biodegradation caused by enzymatic hydrolysis took place on the surface only.
The biodegradation of immiscible blends of PHBV-PS and PHBV-PCL showed higher weight loss rate than the pure PHBV when the contents of PS and PCL were less than 50%. Since there is no interaction between the components of immiscible blends, the PS or PCL will detach as fragments from the PHBV matrix easily. The adhesion between PHBV and PS can be improved by incorporated little amount of PCL as a compatibilizer.
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