Miscibility, crystallization, mechanical, and rheological properties of poly (L-lactic acid)/poly(vinyl acetate) blends

Herein, poly(L-lactic acid) (PLA) and poly(vinyl acetate) (PVAc) with high molecular weight were melt compounded to prepare blends with improved mechanical and rheological properties. Dynamic mechanical analysis (DMA) suggested that PLA and PVAc were miscible. Rheological properties indicated that the addition of PVAc improved the viscoelasticity of PLA melt, resulting in the suppression of cold crystallization of the blends. Isothermal melt crystallization behaviors revealed the addition of PVAc decreased crystallization rate, whereas did not change the crystallization mechanism. Unexpectedly, increases of 38%, 21%, and 55% were achieved in the modulus, yield strength, and elongation at break of blend with 20 wt % PVAc content compared to neat PLA. What is more practical is that the PLA/PVAc blends prepared by simple melt blending process showed the combination of improved stiffness, strength, ductility, and melt strength, which helps to meet the performance and process requirements of PLA in various fields.

Automated summary

Poly(L-lactic acid) (PLA) and poly(vinyl acetate) (PVAc) with high molecular weight were melt compounded to prepare blends with improved mechanical and rheological properties. The addition of PVAc improved the viscoelasticity of PLA melt and suppressed cold crystallization. PVAc also reduced the crystallization rate without changing the crystallization mechanism. The PLA/PVAc blends showed increased modulus, yield strength, and elongation at break compared to neat PLA. The blends prepared by melt blending process exhibited improved stiffness, strength, ductility, and melt strength, meeting the performance and process requirements of PLA in various fields.