The thermal pressure coefficients and densities of PEG (M~n=200), PEG (M~n=300), PEG (M~n=400), PDMS (M~w=15000) and PDMS (M~w=20000) have been measured over the temperature range of 20-90℃. It is found that their thermal pressure coefficients and internal pressures are almost in dependent of the molecular weight. A corresponding state model of internal pressure with only one adjustable parameter for polymers is established, which can be applied to various polymers satisfactorily.

Key words: HIGHPOLYMER, INTRINSIC PRESSURE, POLYGLYCOL, POLYSILOXANE