Surface Free Energy and Flexural Properties of Wollastonite Filled Polypropylene Composites

Abstract

Nowadays, appearance is an important factor in vehicles. For this reason, paint application is widely used in plastic parts. Surface energy is a key parameter for the adhesion of paint on the surface of polymers. Among thermoplastic polymers, polycarbonate and acrylonitrile butadiene styrene are commonly used materials due to their higher surface energies. For low surface energy materials, surface energies can be increased using streamer, plasma, corona, mechanical etching and chemical etching methods. The aim of this work is to eliminate the pre-treatments applied to parts produced with polypropylene (PP) polymer using wollastonite (CaSiO3) additive. For this purpose, CaSiO3 filled PP composites containing 40 wt.% wollastonite with different sizes and coatings were produced by extrusion process. Afterwards, plate samples were prepared from granules using a hot pressing device. Flexural properties and surface free energy measurements were performed on these composites produced in plate form. From the results, an increased surface free energy was observed for small particle size and aminosilane coated wollastonite added PP composite with an increase by 23% of the total surface free energy. Flexural strengths were well correlated with the surface free energy results and showed an increase by 1.2% for the same additive.