Structure-property relationships of in-situ PMMA modified nano-sized antimony trioxide filled poly(vinyl chloride) nanocomposites

Nano-sized antimony trioxide (Sb₂O₃) particles were modified by in-situ methyl methacrylate (MMA)/Sb₂O₃ polymerization. Subsequently, these modified nanoparticles were compounded with poly(vinyl chloride) (PVC) to prepare PVC/Sb₂O₃ nanocomposites. In-situ MMA/Sb₂O₃ polymerization kinetics shows that nano-Sb₂O₃ particles do not inhibit polymerization of MMA. PMMA shell covered on the surface of nano-sized Sb ₂O₃ particles have enhanced interactions with PVC matrix, breaking down nano-Sb₂O₃ particle agglomerates and improving their dispersion in the matrix (average particle size of 60-80 nm) and also increasing the particle-matrix interfacial adhesion. Thus, nano-Sb ₂O₃ particles reinforce and toughen PVC. It was observed that at 2.5wt% of nano-Sb₂O₃ particles modified by in-situ PMMA optimal properties were achieved in Young's modulus, tensile yield strength, elongation at break and Charpy notched impact strength. Detailed examinations of micro-failure mechanisms of tensile specimens showed that nano-Sb₂O₃ particles acted as stress concentrators leading to debonding/voiding and deformation of the matrix material around the nanoparticles. Under impact fracture, the nano-Sb₂O₃ particles prolonged crack initiation time, and increased energy absorptions for crack initiation and fracture propagation caused by strong interfacial interaction between nanoparticles and PVC matrix. These mechanisms lead to impact toughening of the nanocomposites.