微波原位聚合PLA纳米复合材料的结构与性能

Structure and properties of polylactide nano-composite polymerized in situ under microwave irradiation

将D,L-丙交酯和有机蒙脱土(OMMT)在连续微波辐照下开环聚合,合成聚乳酸(PLA)/有机蒙脱土(OMMT)纳米复合材料。对复合材料的力学性能及热性能测试表明,在PLA中加入w(OMMT)为0.1%时,其拉伸强度和断裂伸长率均达到最佳,相对于纯PLA分别提高了60.75%和7.85%;PLA的热失重中心温度提高了8℃.即提高了复合材料的热稳定性。分析复合材料的X射线衍射谱图、透射电子显微镜和扫描电子显微镜照片表明:OMMT主要以剥离状态分散在PLA基体中,形成以剥离型为主、同时存在插层结构的纳米复合材料,OMMT的加入使复合材料的拉伸断面由脆性断裂向韧性断裂转变。

Polylactic acid/organo-montmorillonite （PLA/OMMT） nano-composite was synthesized in bulk via ring opening polymerization in situ of D,L-lactide in the presence of organo-montmorillonite under continuous microwave irradiation. The analyses of mechanical properties reveal that when dosage of OMMT is 1% by mass fraction the tensile strength and the elongation at break of the nano-composite reach its optimum values, increased by 60.75% and 7.85% respectively, compared with pure PLA. The central temperature of heating loss （Tdc） of the PLA/OMMT is 8 ℃ higher than pure PLA as indicated in the thermogravimetric analysis; the in crement in Tdc represents the improvement in stability of the nano-composite. The analyses by scanning electron microscope （SEM）, X-ray diffractometer （XRD） and transmission electron microscope （TEM） confirm that the OMMT, mainly in exfoliated state, is dispersed in the PLA matrix and formed the nano-composite in which the exfoliated structure dominates while the intercalated structure also coexists. The introduction of the OMMT makes the tensile fracture of the nano-composite change from brittle rupture to ductile rupture.