Isothermal Crystallization Process of Poly(l-lactic acid)/Poly(d-lactic acid) Blends after Rapid Cooling from the Melt

Kouta Henmi; Hiroaki Sato; Go Matsuba; Hideto Tsuji; Koji Nishida; Toshiji Kanaya; Kiyotsuna Toyohara; Akimichi Oda; Kou Endou

doi:10.1021/acsomega.6b00098

Isothermal Crystallization Process of Poly(l-lactic acid)/Poly(d-lactic acid) Blends after Rapid Cooling from the Melt

ACS Omega. 2016 Sep 27;1(3):476-482. doi: 10.1021/acsomega.6b00098. eCollection 2016 Sep 30.

Authors

Kouta Henmi¹, Hiroaki Sato¹, Go Matsuba¹, Hideto Tsuji², Koji Nishida³, Toshiji Kanaya^{3

4}, Kiyotsuna Toyohara⁵, Akimichi Oda⁵, Kou Endou⁵

Affiliations

¹ Department of Polymer Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan.
² Department of Environmental and Life Science, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 441-8580, Japan.
³ Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto-fu 611-0011, Japan.
⁴ J-PARC, Material and Life Science Division, Institute of Material Structure Science, High Energy Accelerator Research Organization (KEK), 203-1 Shirakata, Tokai, Naka, Ibaraki 319-1106, Japan.
⁵ Teijin Limited, 2-1 Hinode-cho, Iwakuni, Yamaguchi 740-8511, Japan.

Abstract

We observed the crystallization process in poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) blends using in situ simultaneous small- and wide-angle X-ray scattering measurements with a high-speed temperature control cell. In situ X-ray scattering measurements revealed that density fluctuations larger than the long spacing periods grew during crystallization above 130 °C. In particular, the time evolution of the density fluctuations has a strong dependence on the crystallization temperature. The density fluctuations will promote the crystal nucleation and growth processes of the stereocomplex and increase with increasing crystallization temperature, which is strongly correlated with the complexation of PLLA and PDLA chains. On the other hand, below 120 °C, the kinetics of stereocomplex formation might be hindered by the decreased mobility, and no density fluctuations were observed in the case of homo crystal growth of PLLA or PDLA.