Loong‐Tak Lim

The effects of aqueous and deuterium oxide (D 2 O) solutions of alcohols (methanol, ethanol, 1‐propanol, 2‐propanol, and 1‐butanol) on the thermomechanical properties of poly(lactic acid)—PLA—films were assessed by dynamic mechanical analysis. The glass transition temperature ( T g ) of PLA films immersed in 25%, 50%, 75%, and 100% (v/v) alcoholic solutions were compared with the T g of films immersed in 100% water and D 2 O. The T g of PLA films immersed in methanol and ethanol aqueous solutions decreased as the concentration of the alcohol solutions increased. For methanol and ethanol, the T g decreased by 8.6 and 7.6°C per 25% (v/v) increase in alcohol, respectively. When the PLA films were immersed in propanol aqueous solutions and butanol, the T g reached the lowest value at 75% (v/v) and 100% (v/v), respectively. T g of PLA films immersed in 1‐propanol and 2‐propanol decreased by 8.6 and 8.9°C for every 25% increase in propanol before reaching the minimum value, respectively. Aqueous and D 2 O solutions had similar effects on T g . Selective studies of crystallinity evolution, ethanol sorption, degree of swelling, and Hansen solubility parameters of PLA were conducted. This work assists in developing PLA films intended for contact with aqueous‐alcoholic solutions.