Mechanical and Thermal Properties of Biodegradable Composites Based on graft copolymer LLDPE-g-MA/Gelatin

Abstract

The uncontrolled development of morphology at the stage of formation of biodegradable compositions based on synthetic and natural polymers limits the possibility of achieving satisfactory physical and mechanical and operational characteristics. In the present work, to achieve finely dispersed mixture morphology, an approach was proposed for reactive mixing of functionalized polyethylene with gelatin to form a linear low density polyethylene-grafted-maleic anhydride and gelatin (LLDPE-g-MA/GEL) graft copolymer. Using the selective extraction of the mixture components, we determined amount of graft copolymer LLDPE-g-MA/GEL, free gelatin, mechanical and thermal properties, as well as biodegradability data. It was found that as the amount of maleic groups in the polyethylene macromolecule increased, the amount of graft copolymer increased, and an increase in the content of gelatin in the blend led to a noticeable increase in the elastic modulus, tensile strength, and a decrease in elongation at break. Due to the degradation of gelatin, the thermal stability of the composite (initial temperature) decreased with increasing gelatin content. The maximum rate of destruction of the graft copolymer in the temperature range of 400–500 ºC increased markedly with an increase in the content of gelatin. It was found that the rate of biodegradability would increase with an increase in the content of gelatin in the blend; the maximum level of degradation was observed during the first 10 days and was more than 50 %. It was found that the maximum degree of grafting LLDPE-g-MA and gelatin to each other depended on the amount of maleic anhydride in the graft copolymer. The maximum degree of grafting was observed to be higher with increasing amount of maleic anhydride in the composites.