Quantitative analysis of compositional distribution in biodegradable poly(ethylene oxide)/poly (3-hydroxybutyrate) blend film with compositional gradient by FT-IR microspectroscopy

FT-IR microspectroscopy was used to map the compositional distribution along the cross-section on the gradient films of fully biodegradable poly(ethylene oxide) (PEO)/poly(3-hydroxybutyrate) (PHB) blend system. First, a linear fitting line for a calibration, related the absorbance ratio of two peaks to the fraction of PEO in the blend, was established. During linear fitting, a new equation was deduced and the influence of the different crystallinities on the absorption peaks at the wavenumber 962 and 1342 cm(-1) for PEO, 980 and 1380 cm(-1) for PHB, have been taken into account. For the PEO/PHB blend system, it was found that the crystallinity has little effect on the absorbance ratios of A(962)/ A(1380) and A(1342)/A(1380). Based on the results from the linear fitting, which comes from the relation of the absorbance ratios of A(962)/A(1380) or A(1342)/A(1380) and the combination of the weight fraction of PEO (W-PEO/(1 - W-PEO)), the compositional distributions on the cross-section of three kinds of compositional gradient films of the PEO/PHB blend prepared by different technologies have been successfully estimated. Furthermore, the better method for preparing the PEO/PHB blend film with compositional gradient was found based on the result of the quantitative analysis of the compositional distribution.