Elastomers - An Engineering Material

Abstract

Abstract Elastomers are engineering materials. Defined as nonlinear viscoelastic solids; applications are normally deformations under twenty five (25) percent. Conventional engineering values of shear modulus G and Young's modulus E can be determined in this relatively linear section of the stress-strain relationships. The viscoelastic description indicates a time/temperature relation response. Treloar notes that G is both the shear modulus value and the elastic constant. The high bulk modulus allows us to assume E=3G thus we have several approaches to develop G and utilize the equation G=NκT=ρRT/Mc, (hereby ρ is density, R gas constant, Mc average chain molecular weight, T temperature Kelvin). This allows us to monitor aging by changes in Mc that occur due to network aging. The aging process will be monitored by strain energy density changes, compressive stress-relaxation (CSR) and dynamic mechanical rheologic testing (DMRT)