Preparation of Hierarchical CaSO4 Whisker and Its Reinforcing Effect on PVC Composites

CaSO4 whiskers (CSW) can be used to reinforce PVC matrix to produce light and strong composites. However, the weak interfacial interaction between the smooth CSW and PVC matrix limited the fabrication of PVC composite with perfect mechanical properties. In this work, CaCO3 nanoparticles were coated on CSW surface by wet modification of CSW in Na2CO3 solution at 80°C, which increased the surface roughness of CSW from 56.8 nm to 115.6 nm. The use of the hierarchical CSW rather than the raw CSW in the fabrication of CSW/PVC composite led to the increase of the flexural strength from 86.3 MPa to 113.2 MPa and the impact strength from 56.7 kJ·m−2 to 82.5 kJ·m−2 owing to the enhanced mechanical interlocking between CSW and PVC matrix.