Effect of kaolin ratio on wear, water absorption, acidic resistance, and mechanical properties of thermoset composites

Natural fiber reinforced composites are easy to decompose in nature compared to synthetic fiber reinforced composites. However, due to environmental effects, natural fibers cannot maintain their properties for a long time. This situation has led researchers to search for natural but non-degradable materials. Kaolin is one of the most abundant minerals in nature and is an easy material to obtain. This study investigated the use of kaolin as a potential natural additive for polymer composites. In this direction, different proportions by weight of kaolin were added to two different polymer matrices (polyester and polyvinylester) materials. Mechanical tests were performed on the samples, and a series of tests were carried out to understand the acid resistance, wear resistance and water absorption properties of the samples. Also, SEM images of the fracture surface, wear surface, and surface exposed to the acidic solutions were taken and examined. According to test results, kaolin improved compression strength while reducing tensile and flexural strength. However, serious improvements have been achieved by nearly 45% and 115% in the tensile modulus and nearly 84% and 218% in the flexural modulus of polyester and polyvinylester composites, respectively. Also, kaolin improved acid resistance and wear properties and reduced the water absorption rate of the composites.