Temperature Calibration Thermomechanical Analyzers

To measure the thermal expansion coefficients, a 0.125 in. thick sample was taken from the cured plates. The Increase in length with temperatures was measured by use of a Dupont 941 Thermomechanical Analyzer (TMA), with a heating rate of 5°C/min. The instrument was calibrated with an aluminum standard. Three runs were made for each sample and standard deviations calculated. 

The glass transition temperatures were estimated from deformation tests performed on the very same pellets which were used for x-ray studies. The tests were made by means of a Perkin-Elmer Thermomechanical analyzer TMS-l, calibrated with polystyrene and polymethylmethacrylate. C-13 NMR Spectra were run in deu-terated chloroform at 10wt% concentration and at 450C. A JEOL PFT-100 spectrometer was used (resolution ... 

A temperature calibration procedure for TMA has been proposed (53-55) and subsequently included as an ASTM method (Test Method for Temperature Calibration of Thermomechanical Analyzers, E1363-90). It uses a penetration probe and the melting temperature of one or more standard materials. Pure metals with sharp melting points are the standards often used. An open DSC pan may be used to contain the calibrant material. Another potential material would be the selected shape memory alloy, reported to be reproducible to 1°C (56). Several reviews on temperature calibration for TMA have been published based on ASTM efforts in this area (54,55). Sircar (26) suggests that, when used for elastomer evaluation, temperature calibration for TMA should be conducted with low melting liquids as in DSC. For calibration of the expansion, one manufacturer s manual (TA Instruments) recommends aluminum for calibrating the linear expansion parameter. Other calibration standards suggested for the linear coefficient of thermal expansion (CTE) are lead (57) and copper (58). 

E1363, Test Method for Temperature Calibration of Thermomechanical Analyzers... 

Earnest, C. M. and Seyler, R. J. (1992), Temperature calibration of thermomechanical analyzers Part I—The development of a standard method, /. Test. Eval. 20, 430. 

Seyler, R. J. and Earnest, C. M., Temperature Calibration of Thermomechanical Analyzers Part II - An Interlaboratory Test of the Calibration Procedure, Materials Characterization by Thermomechanical Analysis, ASTM STP1136,... 

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