丙烯酸酯接枝改性天然橡胶增韧聚乳酸

通过在天然橡胶(NR)分子链上接枝甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA),制备了三种丙烯酸酯接枝改性NR:NR-g-PMMA,NR-g-PBA和NR-g-(PMMA,PBA)。采用核磁共振氢谱对三种接枝物进行了化学结构鉴定。将接枝改性后的NR和未改性的NR与PLA采用哈克密炼机熔融共混,分别制备了PLA/NR,PLA/NR-gPMMA,PLA/NR-g-PBA和PLA/NR-g-(PMMA,PBA)共混物,研究了接枝改性NR和未改性NR含量对共混物力学性能和热性能的影响。各共混物的拉伸弹性模量和拉伸强度均随接枝改性NR和未改性NR含量的增加而降低,断裂伸长率和缺口冲击强度随接枝改性NR和未改性NR含量的增加而提高。其中,PLA/NR-g-PBA共混物的断裂伸长率和缺口冲击强度比其它共混物提高的幅度大,当NR-g-PBA的质量分数为5%时,PLA/NR-g-PBA共混物的断裂伸长率达到78%,缺口冲击强度为5.2 k J/m2,而纯PLA的断裂伸长率仅为7.7%,缺口冲击强度为2.5 k J/m2,说明NR接枝分子柔顺性较高的BA更有利于促进其与PLA共混物的韧性提高。热分析结果表明,PLA/NR-gPBA共混物的热稳定性相比于纯PLA也有所提高。

Toughening of Polylactide with Acrylate Grafting Modified Natural Rubber

By grafting of natural rubber (NR) with methyl methacrylate (MMA) and butyl acrylate (BA),three kinds of acry-late grafting modified NR :NR-g-PMMA,NR-g-PBA and NR-g-(PMMA,PBA) were prepared. The chemical structures were char-acterized by hydrogen nuclear magnetic spectra. Polylactide (PLA)/NR,PLA/NR-g-PMMA,PLA/NR-g-PBA and PLA/NR-g-(PMMA,PBA) blends were prepared by melt blending grafting modified NR and unmodified NR with PLA respectively in a Haake internal melt mixer. The mechanical and thermal properties of the blends were investigated as a function of grafting modified NR and unmodified NR content. The tensile modulus of elasticity and tensile strength of the blends decrease with the increase of grafting modified NR and unmodified NR content,but the elongation at break and notched impact strength increase. Among them,the PLA/NR-g-PBA blend shows a higher increasing range in elongation at break and notched impact strength than other blends,when 5%NR-g-PBA is introduced,the elongation at break and notched impact strength of PLA/NR-g-PBA blend is 78% and 5.2 kJ/m2, however,pure PLA shows a 7.7% of elongation at break and 2.5 kJ/m2 of notched impact strength,respectively. Which indicating that by grafting of NR with a flexible polymer like PBA is more beneficial to promoting the toughness of the blend with PLA. The thermal analysis results show that the thermal stability of PLA/NR-g-PBA blend is also improved compared to that of pure PLA.