<p>In this study, attempts were made to diversify the application of potato starch based biopolymer as foam-grade materials. To improve foamability, which is largely dependent on melt strength, it is possible to modify hydrolyzed starch based biopolymers by bulk modification with bi- and multi- functional epoxy chain extenders. The modification work was carried out using a twin screw extruder (TSE) and an internal batch mixer (Haake Mixer) with four different chain extenders. The modified blends were characterized by Parallel Plate Rheometry, DSC, Intrinsic Viscosity and SEM techniques. Finally, foamability of the modified blends was examined by using supercritical CO₂ as a physical blowing agent in a high-pressure batch vessel. Variables such as saturation pressure, saturation time and saturation temperature were adjusted to determine their influence on the cell morphology of the foamed parts.</p> <p>The multi-functional epoxy chain extenders effectively increased the bulk melt viscosity and reduced the crystalline content of both hydrolyzed starch based biopolymers. The intrinsic viscosity measurements were quantified the chain extension reaction, which primarily occurred in the PLA/AAC or PLA phase in both biopolymers and the starch phase made no contribution towards increased bulk melt viscosity. The multi-functional Joncryl^® ADR 4370S was the most effective chain extender for improving the stability of foams by yielding smaller cell size and higher cell density in comparison with the original biopolymer during the batch foaming process at 10 MPa saturation pressure and 30 min saturation time. The use of other chain extenders proved to be mostly ineffectual in producing uniform cellular structure in their corresponding modified biopolymer at those same processing conditions.</p> / Master of Applied Science (MASc)

Wood Plastic Composites (WPC) have advantages over natural wood such as improved stiffness, recyclability, and waste minimization. However, issues such as the difficulty of processing WPC with conventional methods, volatile emission from the wood and the composites’ lack of strength must be addressed. A system for continuous extrusion of rectangular profiles of WPC was developed and some critical processing strategies were identified. The use of a lubricant and a calibrator also improved the profile extrusion of WPC. In this work, glass was also added to improve WPC’s mechanical strength. Generally, a glass content of 2.5% appears to improve the properties but further addition does not have a significant effect. Foaming of WPC, which can enhance their properties, was investigated through studying the effect of heating time and temperature on void fraction and cell density. / UOIT