玉米秸秆/聚乳酸复合材料的制备及性能测试

Preparation and properties of corn stalk/polylactic acid composites

近年来,在资源短缺和环境污染的压力下,生物可降解材料的开发与利用成为学者研究的热点之一。采用熔融共混的方法制备了一种玉米秸秆/聚乳酸生物可降解复合材料,并通过向复合材料中添加3种不同的改性剂对复合材料进行改性处理,旨在提高农林废弃物的附加值及改善复合体系的各项性能。采用X射线衍射、电镜扫描、接触角、力学性能测试等分析手段对复合材料的各项性能进行分析表征,对3种改性剂马来酸酐接枝聚乳酸(MAH?g?PLA)、马来酸酐(MAH)和硅烷偶联剂(KH?550)对复合材料的改性效果进行对比研究。X射线衍射分析的结果表明,MAH?g?PLA改性复合材料的结晶度变化不大,MAH改性复合材料的结晶度显著增加,而经过KH?550改性的复合材料的结晶度较未改性的复合材料有所下降。接触角分析结果表明经过改性之后的复合材料的表面接触角均有所增加,表明复合材料在改性之后的疏水性有所增加。其中MAH?g?PLA改性的复合材料的接触角增加最多,表明MAH?g?PLA能够更好地改善复合材料的亲水性。扫描电镜的断面分析结果表明,MAH和KH?550均有效改善了复合材料的界面相容性,且KH?550改性的复合材料的界面相容性更佳并具有较高的力学强度。力学测试结果表明,KH?550改性的复合材料的拉伸强度提高了5.47%,弯曲强度提高了2.50%。

In environmental pollution and shortage of fossil resource have become the biggest challenge for humans.It is urgent to develop environmentally friendly and biodegradable materials to replace the petroleum?based plastics.In this work,corn stalk and biodegradable plastic polylactic acid(PLA)were used to prepare a green and biodegradable composite.To improve the interfacial compatibility of corn stalk/PLA composites,three different modification agents,namely maleic anhydride(MAH?g?PLA),MAH,and silane coupling agent(KH?550)were added into the corn stalk/PLA composite systems during melt blending process.The effects of the addition of these three modifiers on the performance of corn stalk/PLA composites were comprehensively studied.The results of X?ray diffraction showed that the crystallinity of the composites changed differently via modification with different agents.The crystallinity of MAH?g?PLA modified composites did not show significant increase,while the crystallinity of MAH modified composites increased obviously.However,the crystallinity of KH?550 modified composites decreased.The significant increase of the crystallinity of MAH modified composites could be owed to the better mobility of MAH molecular chains,which?then could enhance the crystallization ability and indicated by the higher melt index of the MAH modified composite than other composites.The contact angles of all the composites increased after modification,indicating that the hydrophobicity of the composites was improved after the modification.The increasement in the contact angle of the composites modified by MAH?g?PLA was higher than the other two composites.The fracture surface of the composites was observed by scanning electron microscopy to analyze the influence of the three modifiers on the interfacial compatibility.The results showed that MAH and KH?550 could effectively improve the interfacial compatibility between the corn stalk and PLA matrix.The composites modified by KH?550 had the best interfacial compatibility,suggesting that KH?550 had better interfacial interaction and adhesion with both corn stalk and PLA than the other two agents.As a result,the composites modified by KH?550 showed higher mechanical strengths due to the better interfacial bonding.The tensile strength of the KH?550 modified composites increased by 5.47%and the flexural strength increased by 2.50%when compared with the unmodified corn stalk/PLA composites.