Al~traet--Ten copolymers of butadiene and acrylonitrile have been prepared covering the composition range 100-25 mole % butadiene; reactivity ratios are rbu~,d~,,, = 0"50, roc,y~.,it,i~ e = 0"07. The thermal analysis techniques (TVA, TGA and DSC) have been applied to determine the general features of the thermal degradation of these copolymers. The fractions of products comprising permanent gases, products volatile at 20 Β° , chain fragment material and residue have been separated and analysed. The constituent parts of the overall reaction have been discussed and the whole represented in the form of an integrated reaction mechanism.
Copolymers and polymer and copolymer blends incorporating two or all three of the monomers: acrylonitrile, butadiene, and styrene, have become important commercial materials. It is therefore important to have information about their stability towards the various degradative agencies. A description of the thermal degradation of copolymers of styrene and acrylonitrile has been given [1]; this paper extends this work to the butadiene-acrylonitrile copolymer system.
EXPERIMENTAL
Purification of materials
1,3-Butadiene (Air Products Ltd.) was purified by distillation (three times) under vacuum, the first and last 10 per cent being discarded at each distillation. Acrylonitrile (Hopkin & Williams Ltd.) was purified by washing with 10% NaOH to remove inhibitor, repeatedly with water to remove NaOH, drying over Call 2 and twice distilling under vacuum. The initiator 2,2'-azoisobutyronitrile was purified by recrystallization from alcohol.