Preparation and Characterisation of PBAT-Based Biocomposite Materials Reinforced by Protein Complex Microparticles

In this work, new biodegradable composite materials based on poly (butylene adipate terephthalate) (PBAT) reinforced with zein–TiO2 complex microparticles were prepared and characterised by electron microscopy and tensile and dynamic-mechanical tests. The composite pellets were prepared by solvent casting with different filler contents, namely 0, 5.3, 11.1 and 25 part per hundred resin (phr), to modify and modulate the properties of the final materials. Scanning electron microscopy (SEM) images showed homogeneous dispersion of the filler, without microparticles aggregation or phase separation between filler and matrix, suggesting a good interphase adhesion. According to tensile tests, Young’s modulus showed an improvement in the rigidity and the yield stress presented an increasing trend, with opposite behaviour compared to other composites. Dynamic-mechanical analysis (DMA) results exhibited increasing storage modulus values, confirming a greater rigidity with a higher filler percentage. The glass transition temperature showed a slightly increasing trend, meaning the presence of an interaction between the two phases of the composite materials. Overall, the produced PBAT composites showed similar properties to low-density polyethylene (LDPE), proving to be promising and more sustainable alternatives to traditional polymers commonly adopted in agri-food fields.