On the reduced susceptibility to stress whitening behavior of melt intercalated polybutene–clay nanocomposites during tensile straining

The paper describes the micro-scale response, mechanism, and susceptibility to stress whitening during tensile straining of polybutene-5 wt% clay nanocomposites, and its comparison with unreinforced neat polybutene utilizing electron microscopy observations. Polybutene-5 wt% clay nanocomposites exhibit increased tensile modulus, significantly reduced susceptibility to stress whitening, and are characterized by lower optical gray level in the plastically deformed stress whitened zone. Furthermore, crystallization studies suggest that the reinforcement mineral increases the rate of nucleation, accelerating the crystallization process. The reinforcement of polybutene with 5 wt% clay alters the primary micromechanism of stress whitening from stress relaxation of the 'fish-scale psiloma' containing tiny voids and subsequent transformation to ridge tearing at high plastic strains to nucleation and growth of large size voids in polybutene-clay nanocomposites. The final fracture in neat polybutene occurs by a mixed mode (brittle and fibrillation), while brittle deformation is the predominant fracture mode in polybutene-5 wt% clay nanocomposites.