30/30 melt temperature measuring method
Vol. 21 #2, October 1994
Trying to measure the melt temperature of an extrudate with a room temperature pyrometer probe will often give a false melt temperature reading because when the cold probe of the pyrometer is inserted into the hot polymer, it becomes sheathed with the polymer that has been cooled by the probe.
A more effective method to measure melt temperature is by using the 30/30 Method. This method is simply to raise the temperature of the probe to approximately 30 degrees above the anticipated melt temperature and then keep the probe surrounded with the hot polymer for 30 seconds. The easiest way to preheat the probe is to place the probe on, near, or in a hole in the die from which the polymer is being extruded. By preheating the probe to 30 degrees above the anticipated melt temperature, just prior to inserting it into the molten polymer, then it requires the probe to actually be cooled by the molten polymer. The lowest temperature reached will be the stock temperature. It also helps to move the probe around in the melt to have the probe more quickly reach a state of temperature equilibrium with the polymer melt. Accurate readings are difficult so repeat the procedure a number of times.
- Tim Womer
See also:
- Effect of temperature
- Melt temperature measurement
- Pyrometers
Return to
Consultants' Corner