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Properties of rigid polyvinyl chloride foam composites reinforced with different shape fillers

In this study, the effect of reinforcements’ shape and type on the mechanical, thermal, and morphological properties of polyvinyl chloride (PVC) foam composites is investigated. For this purpose, three different fillers, longitudinal structure glass fiber, flaky structure mica, and spherical structure fly ash, were selected to prepare PVC foam composites with 0–20 wt% loading. The tensile strength in both 10 wt% reinforced mica and glass fiber composites improved slightly, while it decreased with the addition of 10 wt% fly ash. Flexural strength reached its maximum in mica and fly ash-filled composites at 10 wt% loading. Meanwhile, flexural strength exhibited higher saturation levels of longitudinal glass fibers due to their penetration within the foam cells. Charpy impact strength measurements showed a decreasing trend with increasing the filler content; however, the rate of reduction was the lowest in PVC/glass fiber foam composites. The effect of filler type and geometry on thermal and dynamic mechanical properties of PVC foam composites was studied using thermogravimetric analyzer and dynamic mechanical analysis, respectively. First decomposition temperature of PVC composites dropped slightly with the addition of fillers, where glass fiber-reinforced foam composites exhibited the lowest rate of reduction. The second decomposition step of PVC foam composites shifted toward higher temperatures with increasing the filler content. Fly ash was found to be more effective in improving the second decomposition temperature. The dynamic modulus of mica and glass fiber-reinforced composites showed an increasing trend below and above glass transition temperature, up to 10 wt% loading, while the storage modulus in fly ash-reinforced composites increased with increasing the filler content at a constant rate. Morphological studies revealed that mica flakes with a paralleled structure within cell walls and glass fibers with a penetrated structure within the cell bubbles exhibited higher agglomeration compared to fly ash composites.