Structure‐property relations in polypropylene mica composites

Abstract Polypropylene composite samples with concentrations of mica of 10, 20, 30, 40, 45, 50, and 60 wt percent were prepared under identical conditions by injection molding. The influence of mica concentration on the structure and mechanical properties of the composites was investigated using a polarizing microscope, scanning electron microscope, differential scanning calorimetry, and stress‐strain characteristics. Flexural and impact strengths show an initial rise and then gradual fall with increasing mica concentration. An optimum of these properties occurred at ∼20 wt percent mica. Tensile modulus and heat distortion temperature show a continuous rise; whereas the percent elongation decreased with mica content. These changes in properties are discussed in terms of a skin‐core morphology, transcrystallinity, crystallinity, fracture surface morphology, flake orientation, and interfacial adhesion in these composites. This study helps in optimizing the mica concentration for injection molded composites.