A study on thermal runaway of poly(vinyl chloride) by microwave irradiation

In order to pursue the dehydrochlorination of poly(vinyl chloride) (PVC) by microwave irradiation, measurement of the temperature profile during irradiation is indispensable. An optical fiber thermo-sensor is used to investigate a relation between temperature rise and microwave absorption onto PVC. The following unique results are obtained: (a) at the beginning of microwave irradiation onto PVC, the temperature rises in direct proportion to the strength of the incident microwave power and irradiation time, (b) after exceeding a critical condition, a temperature on PVC starts to rise quickly, namely thermal runaway (TR), (c) the higher the incident microwave power, the higher the TR starting temperature (TRT) is observed and (d) the higher the pre-heating temperature of PVC, the higher is the TRT. Finally, it can be stated that the TRT is influenced not only by the temperature of irradiated materials but also by the irradiation conditions such as the strength of incident microwave and the temperature before irradiation.