Pang, Ming Meng
(2013)
Preparation And Characterization Of Biobased Thermoplastic Starch/Polypropylene Blends For Thermoforming Application.
PhD thesis, Universiti Sains Malaysia.
Abstract
In this study, thermoplastic starch (TPS) derived from agricultural waste sources (i.e., agricultural waste seed, AWS and agricultural waste tuber, AWT) was blended with polypropylene (PP) to form a biobased compound. The utilization of starch-containing agricultural waste can provide a solution for the waste disposal issue, avoiding the conflict of using food crops starch as feedstock and diversify the usage of waste. Native tapioca starch (NTS) and commercially available biobased sample (CS) were also used for comparison. The optimum formulation was identified through a design of experiment (DOE). The biobased compounds were prepared by using twin-screw extruder, which later subjected to sheet extrusion and thermoforming process. The TPS/PP blends were able to meet the minimum 25% biobased content target as required by various biobased international organizations. The biobased materials behaviour were investigated through thermal, physical, tensile, water absorption, aerobic biodegradation, indoor and outdoor soil burial, natural weathering and carbon footprint study. The higher amylopectin content present in the agricultural waste starch blend (i.e. AWS/PP) was more susceptible to thermal degradation than amylose-rich material (i.e., NTS/PP). The onset degradation temperature of starch component has a direct impact on the decomposition temperature of PP. The addition of starch into the PP not only led to a stiffening effect and resulted in an increase in the storage modulus; it also affected the relaxation of the polymer matrix by shifting the thermal transition (i.e., Tg) to a higher temperature.
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