Investigation of the morphology and properties of the polypropylene/low-density polyethylene/wood powder and the maleic anhydride grafted polypropylene/low-density polyethylene/wood powder polymer blend composites

Abstract

The properties of polypropylene/low-density polyethylene and maleic anhydride grafted polypropylene/low-density polyethylene blends, and their wood powder composites are compared in this study. The blends contained equal amounts of polymers, and the wood powder was added into the blends to form polypropylene/low-density polyethylene/wood powder and maleic anhydride grafted polypropylene/low-density polyethylene/wood powder ternary systems. The Fourier-transform infrared analysis of the blends and composites did not provide any evidence of significant interactions between the different components, although the rest of the results clearly showed that maleic anhydride grafted polypropylene and wood powder significantly interacted, and that there was some interaction between maleic anhydride grafted polypropylene and low-density polyethylene. The differential scanning calorimetry and dynamic mechanical analysis results confirmed the immiscibility of polypropylene and low-density polyethylene, and polypropylene and maleic anhydride grafted polypropylene, and indicated that wood powder was distributed in both the low-density polyethylene and polypropylene phases in the polypropylene/low-density polyethylene blend, but most probably only in the maleic anhydride grafted polypropylene phase in the maleic anhydride grafted polypropylene/low-density polyethylene blend. The polypropylene/low-density polyethylene and maleic anhydride grafted polypropylene/low-density polyethylene blends were found to be more thermally stable than the neat polymers, while the presence of wood powder in both polymer blends further increased the thermal stability of the polymers. The blends and composites with maleic anhydride grafted polypropylene showed higher tensile modulus values and lower elongation at break values than the composites with polypropylene, while the stress at break values of the two sets of samples were comparable.