Thermophysical properties characterization of resins during curing using the flash method

J. Blumm1, A. Lindemann1 and S. Schmoelzer1

1Netzsch-Gerätebau GmbH, Selb, Germany

Keywords: flash technique, resins, curing, crosslinking
property: thermal diffusivity, thermal conductivity
material: polymers, resins

For decades, the flash method [1] has been well-known for characterizing the thermophysical properties of solid materials. In a flash test, the front side of a plan-parallel sample disk is heated by a short light pulse. The heat diffuses through the sample and leads to a temperature rise on the rear side of the sample. By measuring this temperature rise versus time, the thermal diffusivity of the sample can be determined. Analysis of the signal height can also yield information on the heat capacity of the sample. Therefore, direct thermal conductivity measurement is possible. Fast measurement times, easy sample preparation, and high accuracy are only some of the advantages of this non-contact, non-destructive measurement technique. Nowadays, characterization of resins is becoming increasingly important for industrial applications. Generally, differential scanning calorimetry (DSC) or dielectric analysis (DEA) are employed to get some information about the curing process. The thermal diffusivity and thermal conductivity are parameters which can be used to follow the cross-linking reaction in a sensitive way. However, the use of the flash technique is not easy for this kind of application. The sample undergoes a transition from a generally high-viscous liquid to a solid during cross-linking which is generally related with some shrinkage. To measure samples like this, an appropriate sample holder is required which can take up the liquid sample and which is not deformed or damaged during the cross-linking reaction. Furthermore, it has to keep the sample in a disk shaped form. Presented in this work are technical details of a special container system, allowing measurements to be carried out on resins and other reactive polymers even if the samples undergo a cross-linking reaction during thermal treatment. Furthermore, measurement results on two different resin materials are shown carried out with a flash device and the new container. The flash results are correlated with other thermal tests to get a more detailed insight into the cross-linking/curing process.

  1. W. J. Parker, R. J. Jenkins, C. P. Butler and G. L. Abbott, J. Appl. Phys. 32 (1961)

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