Rubber Elast Notes

rubber becomes stiffer, i.e. becomes shorter with high heat when stretched, heat is released elastomer = any polymer which exhibits rubber-like elasticity a stretched rubber sample subjected to a constant uniaxial load contracts reversibly on heating the entropy of rubber decreased on stretching the force acting on the polymer molecule is equal to the slope of the free energy vs displacement curve the instantaneous deformation occurring in rubbers is due to the high segmental mobility and thus to the rapid changes in chain conformation of the molecules. the energy barriers between different conformational states must therefore be small compared to the thermal energy (rt).