Green fabrication method of layered and open-cell polylactide foams for oil-sorption via pre-crystallization and supercritical CO2-induced melting

摘要

This paper investigated the condensed state structure evolution of pre-crystallized polylactide (PLA) under supercritical CO2 (scCO(2)) and its influence on the foaming behavior of PLA. An interesting phenomenon was found, in which the pre-crystallized PLA can form a layered condensed state structure with a molten skin layer and a crystalline core at low temperatures under scCO(2), and as the temperature increases, the width of the molten skin layer and the melting degree of the core gradually increases until a uniform non-layered molten state structure is formed. On this basis, layered and non-layered PLA foams were prepared at low and high temperatures, respectively. For the non-layered PLA foam, the skin layer and the core show similar closed or opened cell structure, where the open-cell PLA foams exhibit excellent oil-sorption properties. This paper provides a solvent-free idea for the green fabrication of bio-based and biodegradable oil-sorption foam. (C) 2020 Elsevier B.V. All rights reserved.