EVOLVED GASES BY SIMULTANEOUS TG-MS TECHNIQUE AND ASSOCIATED THERMAL HAZARD IN DRYING OF POLYACRYLONITRILE

Polyacrylonitrile (PAN) is an important industrial polymer. Its therma l decomposition is exothermic and the onset temperature is close to it s drying temperature in industrial production. The thermal decompositi on process of PAN is a self-heating type and can produce many toxic pr oducts. Thus there is a severe thermal hazard associated with its dryi ng process. In the present study the products of thermal decomposition at various heating rates and isothermal temperatures in the presence and absence of oxygen are evaluated using simultaneous TG-MS technique to provide an insight into the mechanism of their liberation and to o btain qualitative knowledge of the associated hazards. The identified gaseous products liberate simultaneously in the temperature range 150- 400 degrees C and their evolution is dependent upon the heating rate a nd temperature. The principal reaction at lower heating rate is dehydr ocyanation. Carbon dioxide liberation is observed, in addition to othe r products, in the presence of an oxygen-inert mixture atmosphere. (C) 1998 Elsevier Science Ltd. All rights reserved.