Thermal Conductivity Measurement of Molten Polymers and Development of Apparatus by Means of Twin-probe.

SATO Sadao, HAYASHI Yuki, HIROSE Minoru

doi:10.4325/seikeikakou.10.213

Determining the thermal conductivity of molten polymers is very important in flow and thermal analyses using computer aided engineering (CAE) programs. The present study introduces a thermal conductivity device that consists of two probes that are inserted into the experimental specimen to be measured and a reference specimen. Using this device, the effect of temperature on thermal conductivity and thermal diffusivity within the range of 50°C to 280°C is determined. The accuracy of the proposed device was determined to be within ±4∼6%. Instrument calibration can be performed easily for each measurement because the instrument incorporates both a reference and measurement probe. The thermal conductivity of crystalline polymers gradually decreased as the temperature was increased, and thermal conductivity shows a minimal value at the melting point. In contrast, the thermal conductivity of amorphous polymers was remarkably independent of temperature. The thermal conductivity of the molten state is 10∼40% smaller than that of the solid crystalline state. In the case of amorphous polymers, thermal conductivity remains relatively constant or increases slightly with increasing temperature. The thermal diffusivity of crystalline polymers showed a similar trend as that of the thermal conductivity, whereas in amorphous polymers thermal diffusivity gradually decreased with increasing temperature.

Thermal Conductivity Measurement of Molten Polymers and Development of Apparatus by Means of Twin-probe.

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