The effect of CaCO3 filler component on mechanical properties of polypropylene

Abstract

The presence of filler can reduce the production cost and in certain condition it can also improve the mechanical properties. CaCO3 is one type of inorganic filler that widely used in polypropylene materials, since it can cover those two requirements above. This work aimed to study the influence of CaCO3 filler in tensile properties of polypropylene. CaCO3 was sieved through a screen to obtain uniform particles size and then filled into polypropylene with filler percentage of 5%, 15%, and 25% of weight, respectively. The mixture was shaped into dumbell specimens by using Injection Moulding Process and a universal testing machine was used for tensile testing according to ISO 527. The results showed that the mixture of 5% (w/w) CaCO3 achieved highest tensile strain and elastic modulus but had the lowest tensile strength, and that of 15% (w/w) CaCO3 attained the highest values of strength. The highest tensile properties are 24.9 MPa for tensile strength, 3.96% for tensile strain and 963 MPa for elastic modulus. Interestingly, increasing the filler content to 25% of CaCO3 caused the reduction in strength, strain and elastic modulus of the composite. Variant with 5% of filler content has the highest value of impact strength, around 168 J/cm2, whereas the lowest value of impact strength can be found in the variant with 25% of CaCO3, the hardness value decreased on the 25% CaCO3. This situation is related to the filler distribution and dispersion within the specimen due to mixing effect in injection moulding process. Scanning Electron Microscope (SEM) was used to explain this condition by observing the fractured area of specimens.