PLA、PPC或PBAT与2次改性小麦秸秆全降解复合材料的力学性能与生态风险

Mechanical properties and ecological risk of degradable composites based on twice modified wheat straw fiber and PLA,PPC or PBAT

制作复合材料是小麦秸秆资源化利用的有效途径之一。小麦秸秆的改性处理对制成的复合材料力学性能有很大影响,且不同的基体材料与小麦秸秆制成的复合材料性能也有所不同。以聚乳酸(PLA)、聚碳酸亚丙酯(PPC)、聚己二酸(PBAT)为基体材料,分别以改性前或碱处理及偶联剂方法 2次改性后的小麦秸秆纤维为增强材料,采用压缩成型工艺制备了6种全降解复合材料,并对制成的6种复合材料进行了力学性能测试与比对;分析了3种改性后小麦秸秆制成的全降解复合材料的降解性能,并通过种子发芽实验研究了它们的浸提液的潜在生态风险。结果表明,2次改性小麦秸秆与基体材料制成的复合材料,其力学性能较原始秸秆与基体材料制成的复合材料有明显的增强,其拉伸、弯曲、冲击强度均有20%~50%的提升。3种可降解材料降解率由大到小的顺序为:PLA全降解复合材料>PBAT全降解复合材料>PPC全降解复合材料。质量分数1%的3种全降解复合材料浸提液对种子发芽过程基本不造成影响。

Producing composite materials is one of the effective ways for the utilization of wheat straw. Modification of wheat straw as well as different matrix materials greatly influences the mechanical properties of the composites. In the present study, poly lactic acid （PLA）, poly propylene carbonate （PPC）, poly adipic acid （PBAT） were taken as matrix materials, and were mixed with modified or unmodified wheat straw fiber as reinforcing material. By compression molding, 6 kinds of fully biodegradable composites were prepared, the mechanical properties （such as tensile, bending and impact strength） of the 6 composites were tested and compared. The degradation properties of composite materials based on modified straw fiber were analyzed, and the potential risk of the composites were investigated by seed germination. The results showed that the mechanical properties of composite materials which were made of twice modified wheat straw and matrix materials was obviously enhanced compared with those made of unmodified wheat straw and matrix materials. Tensile, bending and impact strength of the former increased from 20% to 50% compared with those of the latter. The composites degradation rates decreased in the following order：PLA degradable composites 〉 PBAT degradable composites 〉 PPC degradable composites. The extract liquid of these fully degradable composites with a mass fraction of 1% will almost not affect the germination of seeds.