That's a function of time. "Plasticizers", the chemicals that make plastics varying degrees of bendable†, sweat out of the plastic over time, turning the plasti

That's a function of time. "Plasticizers", the chemicals that make plastics varying degrees of bendable†, sweat out of the plastic over time, turning the plastic stiff/brittle [which is really what plastics are like by default with no plasticizer in them] and the plastic's surface layer either oily or tacky, depending on the particular plastic. (The surface gets oily for "hard plastics", and tacky for "soft-touch" plastics. If you've ever touched a 40-year-old Apple keyboard cable, you know what soft-touch plastic with the plasticizer sweated out feels like.) † 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.