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The Publisher Summary for Handbook of Environmental Degradation of Materials, 2005, Chapter 7 - Chemical and physical aging of plastics {pgs. 153-163}

" This chapter distinguishes between chemical aging and physical aging of plastics. Chemical aging or chemical resistance is simply the effects of chemicals on the plastic. Various examples of chemical aging, including … another type of chemical aging—that is, environmental stress cracking and crazing. Environmental stress cracking is a type of failure that occurs through surface interactions … The effects of physical aging on the failure behavior of a typical brittle polymer, polystyrene, are discussed. Properties examined are creep rupture lifetimes, fatigue lifetimes, and environmental stress cracking … "

In its' entirety, a most excellent read.

BEST!
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