Effect of stereocomplex crystal on foaming behavior and sintering of poly(lactic acid) bead foams

Poly(lactic acid) (PLA) bead foams with stereocomplex (Sc)/alpha crystals were prepared by melt mixing and solid-state foaming methods, independently. A systematic method was applied to evaluate the effect of Sc/alpha crystals on rheological properties and foaming behavior of PLA. The results indicated that the presence of Sc/alpha crystals affected the foaming behavior and the melt elasticity of PLA. Hence, the enhanced rheological properties of PLA had a significant effect on controlling the foaming behavior. As a result, PLA bead foam with an expansion ratio of 24-fold was developed. And, the presence of Sc/alpha crystals could also facilitate the sintering behavior and broaden the sintering process window. Sintered PLA bead foam with finer cellular morphology and strong sintering effect was obtained by inducing an appropriate Sc/alpha crystalline structure. (c) 2018 Society of Chemical Industry