The effect of alcoholic solutions on the thermomechanical properties of immersed poly(lactic acid) films

The effects of aqueous and deuterium oxide (D2O) 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 D2O. 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 degrees 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 degrees C for every 25% increase in propanol before reaching the minimum value, respectively. Aqueous and D2O 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.

Automated summary

The effects of alcohol solutions on the thermomechanical properties of poly(lactic acid) (PLA) films were studied. It was found that the glass transition temperature (T-g) of PLA films decreased with increasing concentration of methanol and ethanol solutions. Propanol and butanol solutions resulted in the lowest T-g values at specific concentrations. Water and deuterium oxide (D2O) solutions had similar effects on T-g. This study provides insights for developing PLA films for use with aqueous-alcoholic solutions.