Don’t Forget to Move the Temperature Probe…

I was discussing the measurement of the polymer temperature with an engineer and he explained a problem he is encountering…

Each of our technicians are getting different results when we they measure the melt temperature… especially when we measure high temperature materials like polysulfone.

note: I asked one of their techs to demonstrate how they measure the melt temperature and he purged the material, inserted a thin-style probe, and recorded the highest temperature reading. I then asked the technician to repeat the process, but when he inserted the probe I asked him to move is around slowly. The result was a temperature which was 15 degrees higher than his previous measurement.
My Response
When measuring a melt temperature, it is important to move the probe around a little. When the probe is inserted into the melt, a skin of cooled polymer forms around the probe. To ensure you are getting the temperature of the melt, you need to use the surrounding material to soften this skin and get some of the interior polymer melt in contact with the probe.


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