热塑性淀粉/生物降解共聚酯共混物流变性能的研究

Rheological Properties of Thermoplastic Starch/Biodegradable Copolyester Blend

研究了热塑性淀粉(TPS)以及TPS/生物降解共聚酯共混物的流变行为,讨论了增塑剂用量、共聚酯用量和熔体温度对流变行为的影响。研究表明,TPS和TPS/生物降解共聚酯共混物熔体呈明显的非牛顿特征;增塑剂的使用可以大幅度改善淀粉的塑化行为,通过调节增塑剂用量,可以在一定范围内控制TPS的流变行为。对于共聚酯和TPS的共混体系而言,在共聚酯用量较低时,流动过程中TPS分子链受到较强剪切力作用而发生断链,共混物熔体表观黏度降低。在共聚酯用量较高时,共混物熔体黏度则表现出对温度有较大的敏感性。TPS的黏流活化能较小,TPS/生物降解共聚酯共混物的黏流活化能随共聚酯用量的增加迅速增大,且随剪切速率的增加迅速降低。

The rheological behavior of thermoplastic starch （TPS） and TPS/biodegradable copolyester was studied. The effects of plasticizer content, copolyester content and melt temperature on the rheological behavior of the starch and its blend were studied. The results showed the starch and its blend were of non-Newtonian pseudoplastic fluids. The starch could be plasticized effectively by glycerol, and the rheological behaviors of the starch could be controlled by adjusting the content of glycerol. The blend of copolyester/thermoplastic starch had a low apparent viscosity in the case of lower content of copolyester, because the molecular chain of the starch would be ruptured by strong shear effect. When the content of the copolyester was high, the apparent viscosity of the blend was more temperature sensitive. Thermoplastic starch had flow activation energy. The flow activation energy of the blend increased significantly with the increase of the copolyester content and decreased rapidly with the increase of shear rate.