Viscoelastic properties of denture base resins obtained by underwater test

摘要: The viscoelastic properties of denture base polymers, such as poly(methylmethacrylate) (PMMA), polycarbonate (PC), polysulfone (PSF) and polyethersulfone (PES) which have been used in current clinical dentistry were investigated. In addition, water absorption, diffusion coefficient into material, cubical expansion, specific volume residual monomer also determined. From the results this study, behaviours polymers discussed. relaxation modulus (Er(5)) was calculated using a stress at 5 s from start measurement for specimen reached an equilibrium moisture content (wet specimen), decreased 23.1 to 25.5% compared with that PMMA stored desiccator (37 degrees C) 1 week (dry specimen). contrast, decreasing ratio 7.0 10.0% PC, PSF PES. It is suggested phenomenon caused by increase (cm3/g) absorption each material. group relatively large comparison other material 1.81-1.85%. This value within range 0.38 1.74% coefficients PES increased approximately 1.5-2.7 times PMMA. Furthermore, expansion wet larger than dry specimen. increasing 1.03-1.10 1. 18-2.38 variation Er(5) temperature those