Evaluation of P-v-T Properties of Crystalline Polymers Using Injection Molding Processes. Part II. Determination of P-v-T Properties in Molten Phase.:Part II. Determination of P-v-T Properties in Molten Phase

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• The usual measurements of P-v-T properties generally need very low cooling rates in order to make the temperature distribution uniform in the specimen, but the cooling rates in injection moldings are very high. The problems concerning the difference of the cooling rates were pointed out and discussed in a previous paper, and a method for determining P-v-T properties was proposed in the solid phase. In this paper we shall present also a method for determining P-v-T properties in the molten phase using the injection molding. The mean specific volume of the polymer in the cavity, that is calculated from the cavity volume and the weight of it can be assumed to be constant after gate-sealing, as long as the pressure of the polymer in the cavity is still above ambient pressure. The relationship among that mean specific volume, the temperature distribution in the thickness direction, and the pressure after gate-sealing has been presented using the Spencer-Gilmore's equation of state. Thereafter, according to the temperature and the pressure developments obtained from the injection molding process, the P-v-T properties in the molten phase were determined using that relationship. The constants of Spencer-Gilmore's equation of state in the molten phase were calculated from these P-v-T properties. The pressure developments and the volumetric shrinkages in the injection moldings were evaluated using the Spencer-Gilmore's equations obtained in both solid and molten phase. It was shown that they were in good agreements with the experimental values. It would be possible to predict more precisely the shrinkage and the warpage in injection moldings with our method.

• 一般社団法人 プラスチック成形加工学会の論文

一般社団法人 プラスチック成形加工学会 | 論文

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