Pressure‐Volume‐Temperature Properties and Transitions of Amorphous Polymers; Polystyrene and Poly (orthomethylstyrene)

摘要: An apparatus based on Bridgman's bellows method, originally devised for fluids, has been constructed use with solid samples. Mercury is employed as the confining liquid. The operating range 0≤t≤200 °C and 1≤P≤2000 bar. Calibration benzene mercury shows an accuracy of ±2×10−4 cm3/g in measurement specific volume change. A detailed investigation two systems, polystyrene poly(orthomethylstyrene) glassy liquid states undertaken. P‐V‐T results both can be well represented by Tait equation, single parameter B exponentially decreasing function T. Similar to earlier result polystyrene, a β‐relaxation region observed terms isothermal compressibility methylated polymer Tβ/Tg≃0.70 both. pressure coefficients transition temperatures are discussed. For glass transition, Ehrenfest‐type equation appears obeyed low‐pressure glasses (formed cooling at a...