| Abstract: | The specific volume of thermoplastic polymers and composites with glass fiber have been measured at high pressure, up to 2000 kg/cm2, in the molten state by a dilatometer. The specific volume and thermal expansion coefficient of the melts increase with increasing temperature at a constant pressure at a constant temperature. The data of specific volume of molten polymers were satisfactorily fitted to an empirical equation of state based on the Tait equation. Furthermore, it is found that the data of specific volume of molten composites were suitably fitted by an additive rule of Tait equation from the volume fractions of specific volume of polymers and the glass fiber in composites. The thermal expansion coefficients of molten polymers and composites are approach to the derivative values of the Tait equation, and the additive Tait equation, respectively. |
