Self-Nucleation Efficiency of PDLA in PLAs: Crystallization Behavior and Morphology

• Published in: Polymer science. Series A, Chemistry, physics Vol. 60; no. 2; pp. 206 - 214
• Main Authors: Zou, Guoxiang, Qu, Xin, Zhao, Caixia, He, Yingjie, Li, Jinchun
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-03-2018
• Subjects: Chemistry; Chemistry and Materials Science; Polymer Blends; Polymer Sciences
• ISSN: 0965-545X; 1555-6107
• DOI: 10.1134/S0965545X18020165

Crystallization behavior and morphology of PLA blended with 0.05–1.00 wt % loadings of poly(
D
-lactic acid) (PDLA) forming stereocomplex crystallites as in-situ nucleating agents, were studied using wideangle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and polarizing-light optical microscopy (POM). Blending PLA with small amount of PDLA does lead to formation of PLA stereocomplex (SC), although the PLA is a random copolymer. The in-situ formed SC crystal acted as nucleation sites in blends and accelerated the crystallization of PLA by decreasing the half-time (
t
1/2
). The nucleation efficiency of PDLA obviously increased and the crystallization induction time decreased while the content of PDLA reached up to 0.20 wt %. While the content of PDLA is 0.2 wt %, the nucleation efficiency of PDLA is up to 43.8%, and the induction time decreased from 430 to 88 s. In addition, compared with pure PLA,
t
1/2
decreases from 15.1 to 3.5 min at
T
c
= 127.5°C while the amount PDLA is 1.0 wt %. The equilibrium melting temperature of PLA decreased from 187.2 to 181.2°C with the increase of PDLA content.