Synthesis and characterization of a new soy protein isolate/Polyamic acid salt blend films

In this study, a new method was developed to produce biodegradable material using soy protein isolate (SPI) as matrix. The blend films were successfully prepared by casting the aqueous dispersions of SPI and polyamic acid salt (PAS) solution. The effects of blending and PAS content on the structure of the resultant films were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) analyses, scanning electron microscopy (SEM). Furthermore, film thickness, water vapor permeability (WVP), water barrier and mechanical properties were measured. The result showed that there exists strong intermolecular interactions between SPI and PAS, which played an important role in forming a homogeneous structure of the blend films. Moreover, the incorporation of PAS enhanced the water barrier and mechanical properties of the films. This is a simple way to prepare biodegradable films compared with other methods and the blend films have the potentiality to be used as food packaging and biomedical materials instead of synthetic polymer.