a study of the crystallization, melting, and foaming behaviors of polylactic acid in compressed co2的研究结晶、融化和发泡行为的聚乳酸压缩二氧化碳.pdfVIP

Int. J. Mol. Sci. 2009, 10, 5381-5397; doi:10.3390/ijm OPEN ACCESS International Journal of Molecular Sciences ISSN 1422-0067 /journal/ijms Article A Study of the Crystallization, Melting, and Foaming Behaviors of Polylactic Acid in Compressed CO2 Wentao Zhai, Yoorim Ko, Wenli Zhu, Anson Wong and Chul B. Park * Microcellular Plastics Manufacturing Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, M5S 3G8, Canada; E-Mails: zhaiwt@mie.utoronto.ca (W.Z.); yoorim.ko@utoronto.ca (Y.K.); wlzhu@mie.utoronto.ca (W.Z.); awong@mie.utoronto.ca (A.W.) * Author to whom correspondence should be addressed; E-Mail: park@mie.utoronto.ca (C.P.); Tel.: +1-416-978-3053; Fax: +1-416-978-0947. Received: 27 October 2009; in revised form: 26 November 2009 / Accepted: 14 December 2009 / Published: 16 December 2009 Abstract: The crystallization and melting behaviors of linear polylactic acid (PLA) treated by compressed CO2 was investigated. The isothermal crystallization test indicated that while PLA exhibited very low crystallization kinetics under atmospheric pressure, CO2 exposure significantly increased PLA’s crystallization rate; a high crystallinity of 16.5% was achieved after CO treatment for only 1 min at 100 °C and 6.89 MPa. One melting 2 peak could be found in the DSC curve, and this exhibited a slight dependency on treatment