ABSTRACT
ABSTRACT: This paper presents an energetic analysis of the mechanical properties of crystallizable Natural Rubber (NR). For that purpose, mechanical tests have been performed with an unfilled NR at increasing maximum stretches. Temperature variations due to both the material deformation and the effects of heat diffusion were measured by using an infrared camera at the surface of specimens under quasi-static and uni-axial loading at ambient temperature. The heat sources produced and absorbed by the material during the deformation cycles are deduced from the temperature variations by using the heat diffusion equation. Energetic balance carried out has shown that no intrinsic dissipation is produced while energy dissipation is observed in the strain-stress relationship [1]. The question is therefore where does mechanical energy go? This paper answers this question. The experiments carried out, the theoretical framework used to perform energy balance and the identification of heat source are first presented in details. Then, energy balances accounting for both the non-entropic and entropic contributions to NR elasticity enable us to clearly identify the physical origin of the mechanical energy dissipated.
