 The white colour is caused by light-scattering from the crazes.Besides, the production of crazing is a reversible process, after applied compressive stress or elevated temperature (higher than glass transformation temperature), it may disappear and the materials will return to optically homogeneous state.Shear banding is the narrow region with high level of shearing strain from local strain softening, it is also very common during the deformation of thermoplastic materials.