Studies on the influences of polyhedral oligomeric silsesquioxane (POSS) on tensile properties of polystyrene

The influences of the polyhedral oligomeric silsesquioxane (POSS) on the mechanical properties of homopolymers were studied. Firstly, the nano scale pole-like models of two kinds of homopolymers, pure polystyrene (PS), and polystyrene attached with 5 mol% propyl-POSS (P-POSS-PS) were built. Then the mechanical behaviors of the two kinds of homopolymers under different tensile strains were investigated by the molecular simulations. The results show that, when the tensile strain of PS reaches 0.06 the micro voids appear. And when the tensile strain reaches 0.08 the necking phenomenon appears. The tensile stress of PS achieves the maximum value when the tensile strain is 0.05, and the corresponding tensile modulus of PS is 2.26GPa. By contrast with PS, when the tensile strain of P-POSS-PS reaches 0.09 the micro voids appear. And obvious necking appears in P-POSS-PS when the strain reaches 0.1. The tensile stress of P-POSS-PS get the maximal value at the tensile strain of 0.04, and the corresponding tensile modulus is 4.1GPa. Conclusions can be made from this work that the tensile strength of homopolymers can be observably improved by the POSS. A small quantity of POSS has little influence on the toughness of homopolymers. This work has realistic theoretical significance to understanding the reinforcement mechanism of POSS and provides important referential message to the applications of POSS.