端羧基聚乳酸的扩链、改性及其性能

Chain expansion,modification and properties of the carboxyl terminated poly-lactide

以丙交酯为原料、辛酸亚锡为催化剂、丁二酸酐为改性剂,采用梯度升温法,在150℃、0.098MPa条件下采用直接熔融缩聚法合成端羧基聚乳酸共聚物P（LA/SA）,接着用2,2-（1,3-亚苯基）-二噁唑啉（1,3-PBO）对其进行扩链,按n（丙交酯）/n（1,3-PBO）=1/2.4加入1,3-PBO,反应1h制得聚酰胺酯（PEA）,最后将高岭土与PEA在150℃、减压条件下熔融复合改性。采用GPC、FTIR、~1H NMR、DSC、SEM等手段对聚合物的结构进行表征和性能测试,结果表明,与P（LA/SA）相比,扩链产物PEA相对分子质量大幅度提高,重均相对分子质量高达24万,玻璃化转变温度T_g高于PLA和P（LA/SA）,改性后复合材料的热稳定性能提高,结晶度降低。

The terminal carboxyl group of polylactic acid copolymer P（LA/SA） was synthesized with lactide as raw material,stannous caprylate as the catalyst and succinic anhydride as modifier by direct melt polycondensation,and under the condition of 150℃ and 0.098MPa（LA/SA）. The polyesteramide（PEA） was synthesized using 2,2-（1,3-phenylene）-bis（2-oxazoline）（1,3-PBO） chain the terminal carboxyl group of polylactic acid copolymer with the n（lactide）/n（1,3-PBO） is 1/2.4 and the reaction time of 12 h. Finally,Kaolin and PEA melting compound was modified under stress conditions at 150℃. The structure were characterized by FTIR and the properties were investigated by GPC,FTIR,~1H NMR,DSC,SEM. The result showed that the relative molecular weight of the chain extender product PEA increased significantly compared with P（LA/SA）,and the heavy molecular weight was up to 240000. Its glass transition temperature is also higher than that of PLA and P（LA/SA）. The thermal stability of the composite material is improved and the crystallinity is reduced after being modified.