增塑剂对淀粉／聚己内酯基共混合物的物理性能和生物降解能力的影响

Effect of plasticizers on physical property and biodegradability of starch/polycaprolactone base blend

利用淀粉聚己内酯基共混物制做可降解塑料近年得到很大的发展。本文主要研究增塑剂（氯化胺、尿素、山梨醇、蔗糖、山梨醇酯60，甘氨酸和酪氨酸）对基础混合物（50：50木薯淀粉和聚己内酯基加上35％的50：50甘油和水）物理性能和生物降解能力的影响。结果表明：除酪氨酸外，随着增塑剂含量的增加，各种增塑剂均有效地降低混合物的熔体粘度，其中山梨醇酯60和氯化胺最有效。用拉伸强度和断裂伸长率表示的机械性能表明：尿素和氯化胺能提高基础混合物的断裂伸长，而酪氨酸能提高基础混合物的抗张强度。生物降解能力试验表明：在脂肪酶和α-淀粉酶的作用下，山梨醇、蔗糖和甘氨酸能增加基础混合物的溶解性和降解性，而氯化胺则降低降解性，近一步研究表明：尿素和山梨醇酯60对基础混合物的降解性影响很小。本项研究表明：基础混合物物理性能的提高依赖于增塑剂类型和增塑剂的含量，我们可以改变增塑剂类型和含量来发展具有不同性质的可降解塑料。

The technology of using starch/polycaprolactone (PCL) base blend for producing biodegradable plastics advances rapidly in recent years. We study the effect of plasticizers (amonium choride, urea, sorbitol, sucrose, span60, glycine, and tyrosine) on the physical property and biodegradability of the base blend of cassava starch: PCL (50:50) with 35% glycerol and water (50:50). We find all the plasticizers, except tyrosine, are effective in lowering the blend melt viscosity, by increasing the plasticizer content. Among all plasticizers, span60 and amonium choride (NH 4Cl) exhibit the greatest efficiency. Mechanical test, described by tensile strength and breaking elongation, indicates that using urea and NH 4Cl would improve the base blend breaking elongation, and using tyrosine would improve the base blend tensile strength. It shows that sorbitol, sucrose, and glycine increase the solubility and degradability of the base blend by lipase or α amylase, while amonium choride decreases the degradability. Further investigation reveals that urea and span60 affect slightly on degradability of the base blend. These results suggest that we can alter the type and concentration of plasticizer to develop a range of biodegradability plastics with different properties.