Study on the measurement of specific heat capacity of plastic composite using differential scanning calorimetry (discussion on measurement accuracy with pure metal and metal-oxide specimens, results for plastic composite specimen)


J. Fujino1 and T. Honda1

1Fukuoka University, Japan

Keywords: differential scanning calorimeter,
property: specific heat
material: plastic composite, metal, metal-oxide

The aim of our work is to investigate the specific heat of both a metal fiber-containing plastic and a plastic waste/fly ash composite. Both plastic composites are made from different ingredients and have different internal structures. This paper deals with measurements of the specific heat capacity of metal-oxide, metal and plastic composites using both a heat-flux differential scanning calorimeter [1] and synthetic sapphire disks, 9.9 to 60.1 mg in mass [2], as a standard reference material. The synthetic sapphire disks have a diameter of 3.5 mm and a purity of 99.99%. One metal-oxide disk (rutile 99.99% in purity [2]) and three metal disks [3] (copper 99.96% in purity, molybdenum 99.95% and silver 99.99%) are used in order to discuss the reliability of specific heat capacity measurement. The heated surface of these disk specimens is polished, and the surface roughness is as low as 0.6µm. The measurement is carried out at temperatures from room temperature to 388 K for the metal and metal-oxide disk specimens. For plastic composite specimens, the measurement is carried out at temperatures below 365 K to prevent the melting of plastic component. The constant heating rates are set at 2, 5, 10 and 15 K/min. For the metal-oxide and metal specimens, the variation in the DSC output and specific heat capacity data decreases with increasing the mass of specimen. Although the variation in the DSC output is not dependent of the heating rates and temperature, the specific heat capacity value differ with the heating rates. The difference is within 3%, when the sapphire disks ranged from 19.7 to 60.1 mg in mass. Then, the specific heat capacity data agrees with literature data [4] within ±3%. In additional, uncertainties are estimated to be within ±5% at temperatures from room temperature to 388K. The specific heat capacity for the metal fiber-containing plastic specimen 18.2 mg in mass increases from 1.1 to 1.4 kJ/(kg•K) with increasing the temperature from 300 to 360 K, when the heating rate are set at 5 K/min. The specific heat capacity value differs with the heating rates and the mass of specimen. The variation in the data is within ±10% of the mean value. The specific heat capacity of the plastic waste/fly ash composite increases from 1.3 to 1.6 kJ/(kg•K) with increasing the temperature from 305 to 360 K, when the heating rates are set at 2 and 5 K/min. In addition, the variation in the data is within ±3%. However, the data for 10 K/min are about 2% lower than those for 2 K/min. The specific heat capacity is not dependent of the shape and mass of specimen.

References
  1. Instruction Manual for DSC22C system (Seiko Instruments Inc., 1994) [in Japanese]

  2. Inspection Report (Shinkosha Co., Ltd., 2006) [in Japanese]

  3. Nilaco Corp., http: // nilaco.jp /

  4. Y.S. Touloukian, E.H. Buyco, in Specific Heat: Metallic Elements and Alloys, ed. by Y.S. Touloukian, C.Y. Ho. Thermophysical Properties of Matter, vol.4 (IFI/Plenum, New York, 1970), pp.51-61, 135-139 and 208-212, in Specific Heat: Nonmetallic Solids, ed. by Y.S. Touloukian, C.Y. Ho. Thermophysical Properties of Matter, vol.5 (IFI/Plenum, New York, 1970), pp. 24-29 and 246-249

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