Mechanical, thermal and flammability properties of dolomite filled polypropylene composites

In this project, the composites of polypropylene (PP)/dolomite were prepared via extrusion and injection moulding. Dolomite mineral was used as reinforcement in PP matrix. PP reinforced dolomite composites with various concentrations of dolomite (5, 10 and 15 wt%) were characterized by mechanical properties through tensile, impact and flexural test, morphological analysis by scanning electron microscope (SEM), thermal analysis by differential scanning calorimeter (DSC) and flammability analysis by the limiting oxygen index (LOI). The incorporation of dolomite into PP had improved Young's modulus while flexural modulus, tensile, flexural and impact strengths were decreased. The incorporation of dolomite up to 15 wt% increased the stiffness of the composites in tensile mode while in three point bending mode, 10 wt% dolomite was the optimum concentration. Tensile and flexural strength showed a slight reduction in the values while impact strength was continuously decreased with the addition of dolomite. SEM images showed poor interfacial adhesion between PP and dolomite, thus supported the decreased of tensile, flexural and impact strengths. The melting and crystallization temperatures (Tm and Tc) of the composites slightly increased with the addition of dolomite. LOI test showed that flammability of the composites decreased with the increasing content of dolomite.