Glass Transition as a relaxation process Thermal history dependence of T. 1 fast cooling 2: slow cooling 185 liquid supercooled liquid 0.84 100h glass 2 Temperature dependence of the specific volume of PvA, measured during heating crystal Dilatometric(膨胀计法) results obtained after a quench to-20C, followed by 0.02 or 100 h of storage. (Kovacs, A.J. Fortschr. Hochpolym. Forsch. 1966, 3, 394)Glass Transition as a Relaxation Process ¾ Thermal history dependence of Tg liquid V crystal glass 2 glass 1 1: fast cooling 2: slow cooling supercooled liquid Tg2 Tg1 Tm T Temperature dependence of the specific volume of PVA, measured during heating. Dilatometric (㟘㛰䇑⌅) results obtained after a quench to –20 qC, followed by 0.02 or 100 h of storage. (Kovacs, A. J. Fortschr. Hochpolym. Forsch. 1966, 3, 394) 3