基于低相对分子质量聚己内酯原位反应增容制备超韧聚乳酸

Super-Tough Polylactide with Low Molecular Weight Poly(ε-caprolactone)by In Situ Reactive Compatibilization

用低相对分子质量聚己内酯二元醇(PCL-OH500)与4,4'-二苯基甲烷二异氰酸酯(MDI)反应共混增韧聚乳酸(PLA)。扫描电镜的表征结果表明,在PLA/PCL-OH500/MDI共混物中,PCL-OH500与MDI原位反应生成的聚氨酯为分散相,PLA为连续相。采用差示扫描量热分析和热重分析研究了共混物的热性能。相比于纯PLA,PLA/PCL-OH500/MDI共混物热稳定性稍有下降。获得的PLA/PCL-OH500/MDI(80/20/0.5)显示了较好的韧性,其断裂伸长率相比纯PLA的5.33%增加了约10倍(48.51%),而拉伸强度和弹性模量仅稍有下降。其增韧机理是分散相颗粒从基体中剥离产生了孔洞,诱导了剪切屈服引起基体塑性形变。

Low molecular weight poly（ε-caprolactone） diols （PCL-OH500） was used to toughen polylactide （PLA） with 4,4′-diphenylmethanediisocyanate （MDI） by reactive blend. In the PLA/PCL-OH500/MDI blend, polyurethane derived from reaction of PCL-OH500 and MDI was dispersed phase and PLA was continuous phase, which was observed in the SEM images. DSC and TGA were employed to study the thermal properties of the blend. The thermal stability of the blend is slightly reduced compared to pure PLA. The resulting PLA/PCL-OH500/MDI（80/20/0.5） blend shows super toughness, and the elongation at break is improved by 10 times to 48.51%, compared to 5.33% of pure PLA, while the corresponding yielding strength and elastic modulus display slightly decrease. The toughening mechanism of PLA/PCL-OH500/MDI blend is plastic deformation of the matrix caused by cavitation, arising from dispersed phase particles debonding from the matrix.