The determining role of clay particles on mechanically induced surface damage and associated stress whitening in polybutene–clay nanocomposites

The potential of atomic force microscopy to quantify the surface topography is combined with the surface features obtained by electron microscopy to examine susceptibility to mechanically induced surface damage in neat polybutene and polybutene–clay nanocomposites. The scratch tracks in polybutene are characterized by ‘fish-scale psiloma’ morphology indicative of compressive plastic deformation and quasi-periodic cracking. While in polybutene–clay nanocomposites, ‘ironing’, which is a less severe surface damage mechanism was dominant. Also, polybutene–clay nanocomposites experience significantly reduced stress whitening, and is characterized by lower gray level in the plastically deformed surface damage region. This behavior is attributed to the effective reinforcement by clay particles that act in concert increasing the tensile modulus of the composite and restricts plastic deformation of the polymer matrix.