聚乳酸/聚丙烯/淀粉复合材料的制备及性能研究

采用模压成型制备了聚乳酸(PLA)/聚丙烯(PP)和PLA/PP/淀粉两种复合材料。主要研究了复合材料的热性能、力学性能和降解性能。结果表明:对于PLA/PP复合材料而言,复合材料的熔融温度先增加后降低,结晶度随PLA的含量增加而变大,而且出现了结晶双峰。力学性能相较与纯PLA,断裂伸长率明显提高,拉伸强度有所下降,最大下降28.02 MPa。降解性能随PLA增加而增强。而对于PLA/PP/淀粉复合材料,熔融温度变为先降低后增加的趋势,复合材料的玻璃化温度也减小,材料的可塑性得到提高;在PLA/PP比例相同条件下,PLA的结晶度有明显提高,PLA的结晶峰强度增加。对于力学性能,淀粉的加入,明显降低了其拉伸强度和断裂伸长率,PLA与PP质量比为3/7时,表现出硬而韧的特性,材料具有单向拉伸,不会立即脆断。对于材料降解性能,淀粉的存在对复合材料的降解能力得到明显的提高,当PLA与PP质量比为3/7时,材料的降解率最高为14.78%,是PLA/PP复合材料最大降解率的4.3倍,并且材料上出现了黄褐色斑点。

Preparation and properties of PLA/PP/starch composites

PLA/PP and PLA/PP/starch composites were prepared by molding.In this paper,the thermal properties,mechanical properties and degradation properties of the composites were studied.The results showed that for PLA/PP composites,the melting temperature increased first and then decreased,the crystallinity increased with the increase of PLA content,and there were two crystallization peaks.Compared with pure PLA,the mechanical properties of PLA/PP increased obviously,and the tensile strength decreased to 28.02 MPa.The degradation performance of PLA/PP increased with the increase of PLA.For the PLA/PP/starch composites,the melting temperature first decreased and then increased,the glass transition temperature of the composites also decreased,and the plasticity of the materials was improved;under the same PLA/PP ratio,the crystallinity of PLA increased significantly,and the crystallization peak strength of PLA increased.For mechanical properties,the addition of starch significantly reduced the tensile strength and elongation at break.The presence of starch could significantly improve the degradation ability of the composite,when the mass ratio of PLA to PP was 3/7,the material was hard and tough.The material had unidirectional tension and would not break immediately.When the mass ratio of PLA to PP was 3/7,the highest degradation rate was 14.78%,which was 4.3 times of the maximum degradation rate of PLA/PP composite,and there were yellow brown spots on the material.