Effects of Heat-, Solvent-, and Photo-Induced Crystallization on Crystalline Structures and Gas Transport Properties through Poly(lactic acid) Membrane.

Poly(lactic acid) (PLA) is an environmentally-friendly biodegradable polymer. It is often used in packages, in automobiles, and for electronics. We can even expected that PLA replaces petroleum-based plastics. PLA crystallization can be controlled by cooling and heating, organic solvents, and vacuum ultraviolet irradiation. This paper focuses on controlling the crystalline structure by thermal-, solvent-, and photo-induced crystallization. The effect of the crystalline structures on PLA membranes on gas transport properties was systematically investigated. Interestingly, unlike common crystalline polymer membranes, the permeability through a crystalline PLA membrane was larger than that through an amorphous PLA membrane. PLA is an interesting polymer, whose gas permeability is not significantly affected by its isomer ratio and crystallinity in the L:D-donor ratio range of 98.7:1.3-50:50 and in the crystallinity range of 0-25%. [ABSTRACT FROM AUTHOR]