Study On Preparation And Properties Of Starch-based Biodegradable Plastics

Starch has an important status in the biodegradable plastics'area compared with other biodegradable polymer, because it has a lot of advantages such as a wide range of sources, low cost and easy to be broken down. In this thesis, starch was dealed with the method of modifing and plasticizing agent, the hydrophobicity and thermoplasticity was improved and the compatibility between starch and other polymer was enhanced; the starch-based biodegradable composites was prepared by starch, LDPE and PBS, the properties and structure was studied. The thesis was composed of four parts:(1) The high content starch/HDPE composite was prepared with the surface of starch modified by the aluminium coupling agent and the stearic acid. The copolymer of ethylene and vinyl acetate(EVA) as compatibiliter were also be added. The effect of the agent content on the structure and properties of composites was studied. The mechanism was analyzed and discussed. The result showed that the properties of composites can be improved while the starch was modified by the aluminium coupling agent and the stearic acid.(2) The optimization of formula was obtained through the method of orthogonal design with the mechanical and processing properties studied. The effect of each factor was characterized by the stepwise regression method with DPS software. The effect of the TPS content on the mechanical and rheology was studied. The result showed that the compatibility between starch and matrix was improved with the starch plastisized by glycerin, and the processing properties were improved too.(3) The TPS/PBS composites was prepared by blending, the low-density polyethylene was added for the hydrophobic of the composites. So was the ethylene vinyl acetate as compatibiliter. The result showed that the tensile strength was increased by the HDPE replaced by PBS, and the impact toughness and the hydrophobic was observably enhanced with LDPE added.(4) The biodegradability of the composites prepared above was measured by indoor soil burial method. It was studied by estimating remainder and bereaving the apparent phenomenon for the change of the composites buried by soil for a long time,and so was the effect on the biodegradability of the composites. The result showed that the increase for more biodegradable component added had a remarkable effect for the biodegradable speed of the materials.