Preparation of high toughness and high transparency polylactide blends resin based on multiarmed polycaprolactone-block-poly(l-lactide)

Abstract

Modification of poly(l-lactide) (PLLA) via blending with two or more polymers is one of the effective approaches used to overcome the brittleness of PLLA, which often requires the addition of a compatibilizer and generate opaque materials. To solve this problem, multiarmed polycaprolactone-block-PLLA (PCL-b-PLLA) was synthesized by consecutive ring-opening polymerization of e-caprolactone and l-lactide using multihydroxyl alcohols as initiator. The structure and composition was confirmed by proton nuclear magnetic resonance and gel permeation chromatography. PLLA/multiarmed PCL-b-PLLA blends with various blend ratios were prepared via melt mixing. The presence of multiarmed PCL-b-PLLA (30%) in the PLLA matrix exhibited more than 80 times improvement in the elongation at break, as compared to unmodified PLLA. The addition of multiarmed PCL-b-PLLA in the PLLA contributed to the enhancement of the storage modulus in the low frequency, which was related to the entanglement of the PLLA and multiarmed PCL-b-PLLA. The blend interface had no obvious phase separation, and showed good adhesion between dispersed block copolymer phases within the continuous PLLA phase. The compatibilization mechanism and toughing mechanism were proposed. The resulting PLLA blends also showed good transparency. The current research opened a new route available to prepare transparent PLA-based resin with enhanced properties. POLYM. ENG. SCI., 2016. © 2016 Society of Plastics Engineers