I never really thought about it much. But I guess this is why my baseplates from childhood want to shatter when bent and my kids just want to bend and go white? Or is that really just a function of time and not material?
† Which ironically makes "plasticizers" actually elasticizers. Plastics are polymers named for how they undergo plastic deformation — "bending and going white", as you say — at pretty low stress levels. "Plasticizers" are ironically chemicals that make plastics into materials that undergo elastic deformation — flopping around without damage — instead.