title: A study of the crystallization, melting, and foaming behaviors of polylactic acid in compressed CO₂.
abstract: The crystallization and melting behaviors of linear polylactic acid (PLA) treated by compressed CO(2) was investigated. The isothermal crystallization test indicated that while PLA exhibited very low crystallization kinetics under atmospheric pressure, CO(2) exposure significantly increased PLA's crystallization rate; a high crystallinity of 16.5% was achieved after CO(2) treatment for only 1 min at 100 degrees C and 6.89 MPa. One melting peak could be found in the DSC curve, and this exhibited a slight dependency on treatment times, temperatures, and pressures. PLA samples tended to foam during the gas release process, and a foaming window as a function of time and temperature was established. Based on the foaming window, crystallinity, and cell morphology, it was found that foaming clearly reduced the needed time for PLA's crystallization equilibrium.
authors.affiliation: Microcellular Plastics Manufacturing Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, M5S 3G8, Canada.
authors.forename: Wentao
authors.initials: W
authors.lastname: Zhai
authors.affiliation: Microcellular Plastics Manufacturing Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, M5S 3G8, Canada.
authors.forename: Yoorim
authors.initials: Y
authors.lastname: Ko
authors.affiliation: Microcellular Plastics Manufacturing Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, M5S 3G8, Canada.
authors.forename: Wenli
authors.initials: W
authors.lastname: Zhu
authors.affiliation: Microcellular Plastics Manufacturing Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, M5S 3G8, Canada.
authors.forename: Anson
authors.initials: A
authors.lastname: Wong
authors.affiliation: Microcellular Plastics Manufacturing Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, M5S 3G8, Canada.
authors.forename: Chul B
authors.initials: CB
authors.lastname: Park
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D003460:Crystallization; D005615:Freezing; D007700:Kinetics; D019344:Lactic Acid / Q000737:chemistry*; D011091:Polyesters; D011108:Polymers / Q000737:chemistry*; D011312:Pressure; D013696:Temperature; D014835:Volatilization
chemical_list: D011091:Polyesters; D011108:Polymers; D002245:Carbon Dioxide; D019344:Lactic Acid; C033616:poly(lactide)