Evaluation of relationship between molecular behaviour and mechanical strength of pullulan films.

This study aimed to investigate the relationship between the physical properties and molecular behaviour of pullulan films. To study its thermal behaviour, we obtained a pullulan film by the solvent cast method and analysed it by differential scanning calorimetry (DSC), thermogravimetry analysis (TG), thermo-mechanical analysis (TMA) and FT-IR spectroscopy. The pullulan film contracted with an increase in temperature, and the film contraction depended on the decrease in water content in the film. The FT-IR spectra of a pullulan film was used as a calibration model set to establish such a model to predict the film contraction and water content by principal component regression (PCR) analysis. The film contraction and water content could be predicted using a calibration model obtained by PCR. The molecular behaviour of pullulan films due to film contraction and decreased water content were demonstrated by analysing the regression vector consisting of PC1 and PC2.