Water sorption and physicomechanical properties of corn starch‐based films

The mechanical performance of thermoplastic starch (TPS) films and films made of TPS blended with an aliphatic polyester (APTPS) was investigated after exposure to water mixtures of various compositions and different levels of relative humidity (RH). Conditioning of TPS films at various RH levels resulted in a noticeable absorption of moisture, particularly at high RH levels, and their mechanical properties decreased significantly. High magnification imaging of the films revealed the presence of significant microcracking on the surface of the TPS films which could potentially result in the increased water absorption and consequent reduction in mechanical integrity. The APTPS film was free of any visible microscopic defects and was also less susceptible to water ingress. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013