Study On Starch-based Bio-degradable Plastic

Starch is one of natural macromolecule compounds which could be bio-degradable,regenerate,cheap and easy to preserve and advantageous for transportation.Starch could reaction with different compounds,give birth to many ramifications with good using ability and bio-degradation which is the postulate to produce bio-degradation materials.In this paper,Graft copolymer of corn starch and different monomers such as; methyl methacrylate(MMA)was synthesed with ceric ammonium nitrate as initiator. The effect of monomer concentration,initiator concentration,reaction temperature and reaction time on monomer conversion(C%),grafting efficiency(GE%)and grafting(G%)has been also studied.Finally determined the optimum reaction conditions list as follows;1.Grafting reaction of starch and MMA;when The initiator content was 2.8%, the monomer content was 7.5%,stir responded 3.3 hours of the nitrogen atmosphere,the the maximum graft ratio can reach to 65.9%,the grafting producing could resisting 275℃,and weightlessness about 80%at 335℃,then be decomposed gradually with the rising of the temperature.2.Grafting reaction of starch,MMA and VAc;when the Monomer proportion (VAc;MMA)was 1;2,the initiator content was 3%,the total monomer content was8%,sealed and stir 3.3 hours of the nitrogen atmosphere,the maximum graft ratio can reach to 67.4%,but the thermal stability of the graft product is not very good, the weightlessness ratio is only 5.63 before heat to 241℃,the range of heat-resistance is small,and when heat to 345.4℃,the weightlessness ratio could reach to 35.8%,besides with the rising of the temperature,the sample could be oxidation down to decompose completely after fused during 182℃-229℃.3.Grafting reaction of starch,MMA and St;when the Monomer proportion(VAc; MMA)was 1;1,the initiator content was 2.8%,the total monomer content was8%,sealed and stir 3.3hours of the nitrogen atmosphere,the maximum graft ratio can reach to 61.2%,the thermal stability of the graft product is good,the weightlessness ratio is only 10.6 before heat to 276℃,and when heat to 333.4℃,the weightlessness ratio could reach to 66.7%,indicated that the graft product has good thermal stability could be used to make common plastic materials.The different stem grafting percentages of the three kind grafting reaction is not very big when compared the products of the three kind grafting reaction,and use the mixtures of two monomers is quite expensive and moreover responds complex, does not fit to industrialization production.Finally heat the starch to 80℃dextrinize 2h,keep warm 0.5h,then cooled to 40℃,add 2.8%CAN initiator,7.5%MMA monomer,sealed and stir 3.3hours of the nitrogen atmosphere,using the screw rod center distance is 32mm,expects the tube diameter phi300mm major axis compared to L/D is 12.5 double screw rods extruding machines,controls the screw rod rotational speed 100rpm sample water content when 20%squeezes out,and the results indictated that the sample may bear 302℃within the high temperature,the water resistance is 14.7%,buried in the simple earth passes through about 180 day to be allowed to achieve the nearly 60%weightlessness rate, and can be basically completely degrades.