Polyurethane/Soya Protein Isolate Green Composites: Spectral, Microstructural, Thermal, Swelling, and Biodegradation Behaviors

Abstract

ABSTRACTA series of polyurethane (PU) green composites were synthesized with varying amounts, viz. 0, 2, 4, 8, and 12 wt% of soya protein isolate (SPI). Formation of the urethane linkage in the prepared green composites is revealed by infrared spectroscopy. The glass transition temperature (Tg) of the fabricated PU/SPI composites has been evaluated by differential scanning calorimeter. Thermal stability and degradation analysis of the PU/SPI composites have been performed using a thermogravimetric analyzer (TGA). TGA thermograms clearly revealed that the fabricated composites were thermally stable upto 181°C and show a three‐step of thermal degradation. The water uptake behaviors of PU/SPI systems have been studied at different chemical environments such as distilled water, salt solution, acidic and alkaline solutions. The microcrystalline parameters such as crystallite size (〈N〉) and surface weighted crystal size (Ds) have been evaluated from wide‐angle X‐ray scattering profiles using two different asymmetric distribution functions. PU/SPI green composites were subjected to biodegradation in the presence of Aspergillus niger. The structure–property response of the PU/SPI green composites has been established on the basis of these parameters.