Bulk Compressibility and Its Recovery Behavior of Polymer Melts

The effects of pressure on the loading time in volumetric compression 4formation at a constant temperature are discussed.The results were as follows:(1) The relations among the instantaneous elastic strain eo, instantaneous strain recovery eo', retarded elastic strain er, and retarded strain recovery er', are expressed by the following formula;for loading; for unloading; Where p is pre f sure in kg/cm 2, t and t' duration of loading time and time after unloading, eR = (er) t=∞, λ and λ'retardation time, a, α, α', μ and ν, constants depending on materials, temperatures and pressures.(2) The retarded elastic strain of crystalline polymers is affected by the pressure induced crystallization found by B. Maxwell on polyethylene melt.(3)πr, one of the constants of R. S. Spencer's state equation for crystalline polymers is generally smaller than those for amorphous polymers, and the constant ω becomes small with the specific gravity of polymers.