Impact properties of acrylic denture base resin. 2. Effect of temperature and residual monomer on impact characteristics.

The temperature dependence of the impact strength, resilience, and toughness of the acrylic denture base resins on temperature changes was examined by using a modified impact testing machine. In addition, the creep properties and the residual monomer of their resins were measured; and considering these properties, the impact characteristics of the denture base resins were discussed. With an increase in temperature, the impact properties of all the acrylic denture base resins tested decreased. Furthermore, there was an adequate correlation between the impact characteristics and the amount of the residual monomer. The coefficient of correlation was 0.92 for the impact strength, -0.95 for the resilience and 0.94 for the toughness. For the cold cured acrylic resins, both elastic moduli obtained by the impact test and by the creep test increased obviously according to an increase in the time which elapsed after polymerization.