Morphology, Structure, Miscibility, and Properties of Wholly Soy-Based Semi-interpenetrating Polymer Networks from Soy–Oil–Polyol-Based Polyurethane and Modified Soy Protein Isolate

Abstract

A series of wholly soy-based semi-interpenetrating polymer networks (semi-IPN) have been successfully prepared from soy–oil–polyol-based polyurethane (S-PU) and modified soy protein isolate (M-SPI). Morphology, structure and miscibility of the semi-IPN films have been investigated by Fourier transform infrared (FT-IR) spectroscopy, film density, scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and ultraviolet–visible (UV–vis) spectroscopy. The results show that the hydrogen bonds existing between S-PU chains are partially destroyed during the loading of M-SPI. In addition, the measured density of semi-IPN films are higher than the theoretically values, indicating the penetration of M-SPI into S-PU networks to bind intimately. Good miscibility between S-PU and M-SPI is confirmed by the single Tg observed in DSC and the high light transmittance under low M-SPI content (<20 wt %). Furthermore, DSC and...