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A Study on p-v-T Properties of Amorphous and Crystalline Polymers
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Sato, Sadao / Oyanagi, Yasushi
The p-v-T device which we previously developed was used to investigate a polymethylmethacrylate (PMMA), a polycarbonate (PC) in the liquid and glassy states, a standard high density polyethylene (PE), a nylon-6 (PA6) and a polyphenylene sulfide composites containing 40wt% glass fibers (PPS), ranging from the room temperature to 250 and from the atmospheric pressure to the pressure of 187MPa. This purpose is to measure the p-v-T properties of these polymers in the three measurement techniques of isobaric, isothermal and isochoric. The results show that the straight line Tm' which consists of each melting point Tm of PE in the isobaric technique is 15`25 higher than that in the isothermal technique. The gradient Æb (in the isobaric) and the gradient Æt (in the isothermal) of each v-T diagram at temperature beyond the Tm' lines are Æb<Æt in the each pressure. The p-T diagrams of PMMA, PC, PA6 and PPS obtained by the isochoric technique are presented in the two different straight lines. The intersection of these lines correspond to either the melting temperature Tm or the glass transition temperature Tq in the polymers, but those temperatures are 50`80 higher than the real temperature, because the loaded pressure of the polymer in a closed barrel was relaxed.
Key words: p-v-T / Isobaric / Isothermal / Isochoric / Compressibility / Pressure relaxation