TR: A new characteristic temperature for thermoplastic polymers

Treatment of thermal data of fluids at their critical point T c and of 31 polymers at their T g according to a modified Goldhammer equation indicates that at these points they have a fractional free volume (FFV) averaging 0.113 magnified image and yields T R′S characteristic of each polymer. The FFV values obtained from magnified image showed small deviations from 0.113. These were in the direction and order of magnitude of chemically similar fluids at their T c . When T R = 2T g , eq. (2) reduces to FFV = (a L – a G ) T g . Plots of FFV versus T R – 2T g show similarities in polymeric homologs behavior. A modified WLF equation with C 1 = 3.85, C 2 = 0.113/ (a L – a G ) , and T – T g = T R – T g places all the data on a single curve. The stress concentration coefficient γ of long‐term polymeric strength is temperature dependent. magnified image