The distortion of molecular chains in amorphous crosslinked networks from their most probable configuration by Stretching gives rise to a decrease in configurational entropy. As a consequence, the tendency toward crystallization is so enhanced that even natural rubber can crystallize upon stretching at room temperature. e Crystallization developed in rubber strtched in sim- A pie extension has been directly investigated by X-ray, Ik density and other methods , When crystallization takes place in rubber upon stretching, the resulting crystallites prevent slippage of chain molecules past each other because these crystallites act as multifunctional crosslinkages . As a consequence, raw rubber docs not show any plastic flow at higher extensions. This was observed by Treloar^ from an experiment on the recovery of deformed rubber to its original length upon warming.