Multiple molecular relaxations of hot‐drawn and quenched polymers above their glass transition temperatures

Abstract Thermal shrinkage of highly hot‐drawn and quenched poly(methyl methacrylate) and polycarbonate of bisphenol A were measured. PMMA shows three‐step thermal shrinkage under suitable experimental conditions above its glass transition temperature (Tg). Polycarbonate exhibits four kinds of molecular relaxation associated with shrinkage around and above its Tg. The effect of hot‐drawing and quenching conditions on shrinking behavior is discussed. Almost all of the molecular relaxations are observed above Tg. The molecular origins of the relaxations are discussed in relation with the so‐called T11 transitions of polymers.