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.

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It is necessary to determine the exact material properties in order for analyze the residual stress generated in molds by using theories such as linear viscoelastic and etc. In this paper, a method of estimating the coefficient of thermal expansion which directly effects the residual stress generated in molds was studied based on numerical analysis using a thermoviscoelastic model. The basic equations, which can estimate the distributions of coefficient of thermal expansion in the thickness direction of molds, were derived. Distributions of coefficient of thermal expansion in the thickness direction of polypropylene (PP) resin molded plates were calculated by using the above basic equations and experimental results of residual stress and the coefficient of thermal expansion in arbitrary thickness. By comparing the numerical results and the experimental results, validity of a method of estimation proposed in this paper is discussed.

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『成形加工』第 11 巻第 7 号 (7 月号) 目次において, 下記の箇所に誤りがございました. ここにご迷惑をおかけした筆者および関係者の皆様に深くお詫びを申し上げ, 今後はこのような過失のないよう十分に注意し, 万全の管理を心掛けます.

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成形加工 7 月号 (第 11 巻第 7 号) の 560 ページに掲載された図7の引用もとに関する表記が不正確でした. 図 7 は以下の文献より引用いたしました.

33) Otsuki, Y., Kajiwara, T., Kihara, S. and Funatsu, K. : PPS-14 (Yokohama, Japan), 697 (1998)

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(著者 : 山部　昌)

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