We're studying the stability and fusion behavior of multiple PVC compounds in a Brabender. After a few trials, we set the temperature at 195 °C and the rotor speed at 70 rpm. Samples differ in weight and volume, though each contains at least 45 phr PVC S65.
According to the scientific literature on PVC, the standard torque-time plastogram should show a sharp loading peak right at the start of the measurement and a sharp fusion peak not much later. However, the plastograms we have recorded, do not exhibit these two initial distinct loading and fusion peaks. There is, however, a second much broader peak, which based on the intense dehydrochlorination observed, can only be due to the degradation of PVC.
All this would have been fine, had we not experienced difficulties in determining the fusion time and the dynamic thermal stability using our plastograms. I have found some sources with plastograms similar to ours, yet they are rare and cannot fully and convincingly explain our observations.
Can anyone help explain why we are not getting the standard plastograms? I've attached the plastogram of our neat PVC sample processed under the abovementioned conditions.
Evaluation of PVC compound on the Brabender torque ...
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Wiley Online Library
https://onlinelibrary.wiley.com › pdf › vnl.730040306
a rigid PVC compound with the critical points noted. Point 1 is the fusion peak. Torque, time, and temperature are noted at this point. Fusion is pri-.
Missing: one initial
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