Effect of compatibilisers on mechanical, barrier and antimicrobial properties of iPP/ZnO nano/microcomposites for food packaging application

It is investigated the effects of the addition of three PPgMA, with different molecular weight and maleic anhydride content, on the structure, morphology, mechanical, thermal and antimicrobial properties and oxygen permeability of iPP/ZnO 98/2 wt% composite. The composition of iPP/PPgMA/ZnO composites is fixed at 88/10/2 wt%, that is, about 10 wt% of iPP is substituted with PPgMA. The composites are prepared via melt mixing by using a twin-screw extruder. The ZnO is obtained in a preindustrial scale spray pyrolysis platform. The Fourier Transform Infrared spectroscopy indicates that the ZnO particles, in all the ternary composites, react with maleic anhydride groups of PPgMA. From the analyses of the mechanical properties, permeability to oxygen and antibacterial activity against E.Coli, it is concluded that the best compatibiliser among the three is PPgMA with 1.4% of MA and Mw 65,000, but the antibacterial activity is much lower than that of the binary iPP/ZnO 98/2 wt%. Moreover, it is found that the antibacterial activity is more efficient for the film that presents clusters of the ZnO particles on the surface than the film with ZnO particles smaller and better distributed on the film surface, and embedded in it.