Study on mechanical properties and phase morphology of polypropylene/polyolefin elastomer/magnesium hydroxide ternary composites

In this work, elastomer‐toughened polypropylene (PP)/magnesium hydroxide (MH) composites with ethylene–octene copolymer (POE) were prepared in a twin‐screw extruder and then injection‐molded. The structure, mechanical properties, phase morphology, and rheological behaviors of PP/POE/MH ternary composites were studied. The mechanical properties and fracture behaviors of PP/POE/MH ternary composites are strongly influenced by the incorporation of POE copolymer. The addition of POE causes a significant improvement in the impact strength of the composites, from 3.6 kJ/m² in untoughened composites to 47.4 kJ/m² in PP composites containing 30 phr POE. This indicates that POE is very effective in converting brittle PP composites into tough composites. Conversely, the tensile strength and the Young's modulus of the composites decrease with respect to the PP composites, as the weight fraction of POE is increased to 40 phr. Scanning electron microscopy (SEM) study shows a two‐phase morphology where POE, as droplets, is dispersed finely and uniformly in the PP matrix. The rheological behaviors show that the interfacial interaction in the composites is enhanced with increase in POE content. Interparticle interactions give rise to the formation of interparticle network. Copyright © 2009 John Wiley & Sons, Ltd.