TSD/TMA

The TSD/TMA combination is a typical example of a system developed to measure the same physical property i.e. the glass-rubber transition, on the same sample and at the same time using two independent techniques. 

An old but still properly working Perkin Elmer IMS-1 was adapted to perform TSD/TMA experiments. The TMS-1 is schematically drawn in Figure 6.1 together with some of the important dimensions. The sample, between the probe and the quartz glass sample holder is placed in the furnace. The furnace temperature is programmed to increase linearly with the time. The thermal expansion of the sample is measured via the probe by the linear variable displacement transducer (LVDT). A thermocouple, placed as close as possible to the sample is giving the sample tenperature information. 

The sample holder system had to be modified to perform TMA/TSD measurements simultaneously. This modification is reproduced enlarged in Figure 6.2. The TSD/TMA sample disk (l mm. thick,... 

This TSD/TMA combination proved to be a convenient (small sample size) and sensitive system for the determination of glass-rubber transition effects of several experimental polymer systems, especially in cases where the DSC technique failed due to a lack of sensitivity. The advantage of this dual technique was especially felt during the investigation of experimental samples with unknown Tg-values. In such situations the confirmation of the Tg-value by a second independent technique is often very valuable. 

Simultaneous TSD/TMA measurement on a PVC sample with 10%wt. impact improver... 

An example of a PVC orientation depolarisation effect, measured with a combined TMA/TSD system is given in chapter 6. These orientation depolarisation effects were measured on small (i.e. 8 mm.) diameter, samples. Such samples proved to be too small, however, to detect the space charge depolarisation effects in non-polar SSBR rubbers. These non-vulcanised rubber samples were pressed, therefore, at 140°C between two (l mm thick) brass disks with a diameter of respectively 110 mm (high potential electrode) and 80 mm (low potential electrode) to a sample thickness of about 0.2 mm. A ring (inner/outer diameter 75/85 mm) of 50 micron thick Vespel foil avoided shortcircuiting between the two brass disks. 

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