凹凸棒黏土对聚乳酸结晶性能和热稳定性能的影响

采用熔融共混法分别制备了凹凸棒黏土质量分数为1%、 3%和5%的纳米凹凸棒黏土(ATT)/聚乳酸(PLA)复合材料, 研究了ATT对PLA结晶性能和热稳定性能的影响。结果表明, ATT与PLA基体具有较好的相容性, 当ATT含量低于3%时, 可以均匀的分散在PLA基体中, 而达到5%时则会发生团聚。FTIR结果表明, ATT与PLA基体之间存在较强的相互作用。ATT可明显促进PLA的结晶, 起到异相成核的作用。ATT纳米颗粒的添加引起了PLA冷结晶峰向低温方向移动, 使冷结晶温度从114.4 ℃降低至103 ℃左右。含ATT体系结晶速率比纯PLA快, 表明ATT的加入可以促进PLA的结晶, 说明ATT是PLA有效的成核剂之一。添加ATT可明显加快PLA的结晶速率并减小球晶尺寸。当添加3%ATT时, ATT/PLA复合材料的热分解温度比纯PLA提高了11 ℃, 这主要是由于ATT/PLA网络密度的提高, 使ATT在PLA的降解过程中能够起到较好的阻隔作用, 抑制了PLA的降解自加速过程。

Effects of attapulgite on crystallization and thermal stability properties of poly (lactic acid)

Nano attapulgite/poly(lactic acid) (ATT/PLA) composites were prepared by melting blend with 1%, 3% and 5% mass fraction of attapulgite respectively. Effects of attapulgite on the crystallization and thermal stability properties of PLA were studied in this paper. Results show that the ATT has good compatibility with PLA when its content is less than 3%, but ATT forms in bundles when the content is more than 5%. FTIR results show there are strong interaction between ATT and PLA matrix. ATT has the function of nucleating agent and leads to accelerate the crystalline rate of PLA. In addition, the cold crystallization peaks of various nano ATT/PLA composites shift from 114.4 ℃ to 103 ℃. The crystallization rate of nano ATT/PLA composites is faster than that of the neat PLA, which indicates that ATT is one of the efficient nucleating agent for PLA. ATT can accelerate the crystalline rate of PLA and decrease the size of the spherulite with the increasing of the ATT content loading. The thermal decomposition temperature of nano ATT/PLA composites is about 11 ℃ higher than that of the neat PLA, when the ATT content is 3%. The reason is due to the forming of higher density network between PLA and ATT, which suppresses the degradation of PLA.