Microstructures and properties of polybutylene succinate/soy protein isolate composites compatibilized by in situ graft copolymer

Polybutylene succinate (PBS)/soy protein isolate (SPI) bio-composites were in situ compatibilized with addition of dibenzoyl peroxide (BPO) and polyethylene glycol (400) diacrylate (PEG400DA) by melt processing. The microstructures and various properties of the uncompatibilized and compatibilized bio-composites were investigated thoroughly. The increased tensile strength and water resistance of the compatibilized composites were ascribed to the improved compatibility and enhanced adhesion in the composites. The results of Fourier transform infrared spectroscopy (FTIR), Soxhlet extraction experiments, scanning electron microscopy (SEM) and dynamic mechanical analyses (DMA) revealed the presence of the in situ graft copolymer (SPI-g-PEG400DA-g-PBS), which strengthened interfaces between PBS matrix and SPI domain. The in situ graft copolymer improved the hydrophobicity and thermal stability of the composites. Moreover, it also augmented the entanglements between the phases and increased viscosity and elasticity of the melt. Furthermore, the crystallinity of the composites was also increased by the grafts. However, the crystal structure of PBS was not modified in the bio-composites.

Automated summary

Polybutylene succinate/soy protein isolate bio-composites were compatibilized by in situ graft copolymerization with the addition of BPO and PEG400DA. The presence of the graft copolymer strengthened the interfaces and improved the water resistance and thermal stability of the composites. It also increased the viscosity, elasticity, and crystallinity of the melt.