Study On Preparation Of Hydroxypropylated Cross-linked Starch Films By Extrusion Blow Molding

The traditional plastic industry was based on petroleum products and it was faced the problem of the oil crisis and the environment pollution for the plastic waste. In order to reslove the problem, the research of starch film as the plastic's succedaneum had became the issue of international scientists and engineers.Starch film was available, easily dissolved in water and degradable. The research and application on starch film was known as an international issue because of its excellent characteristics in environment. In this study thermoplastic starch was prepared by twin screw extruder, hydroxypropylated cross-linked starch as raw material, glycerol as plasticizer, pullulan as binder and stearic acid as lubricant. This paper also studied the effect of glycerol on liquidity, thermodynamic properties, microstructure and thermal stability. Starch films were prepared by molten extrusion blow molding with thermoplastic starch. The effects of glycerol, pullulan, stearic acid on mechanical property were studied. The main results were as follows:1. Expansion rations was received by response surface analysis, the effects of glycerol﹥melting temperature﹥rotation frequency of screw.2. The effects of thermoplasti's expansion ration, glass-transition, enthalpies, liquidity and film's mechanics properties for glycerol were researched. With the additive amount of glycerol 28%, thermoplastic starch's glass-transition temperature was 72.8℃and enthalpies was 0.4J/ (mol·g).There were good property on rheological behaviour and mechanics properties.3. The effects of pullulan and on properties of starch films were studied. The results showed that: the additionof pullulan10%, stearic acid0.4%, was the better additions.4. The better humidity of environment 40% was good for film's mechanics properties.On this condition, glycerol 28%, pullulan 10% and stearic acid 0.4% the film's transverse tensile strength of the starch film was 5.18Mpa, and transverse elongation at break was 121.0%; portrait tensile strength was 5.03 Mpa, and portrait elongation at break was 118.0%. 5. The thermoplastic starch belongs to pseudoplastic fluid, and we can improve the liquidity by increasing temperature and the rate of shear.