Thermal Degradation of Polyacrylonitrile, Polybutadiene, and Copolymers of Butadiene With Acrylonitrile and Styrene

Polybutadiene and a co poly mer consisting of 76.5 percent butadiene and 23 .5 percent of styrene were investigated as to t he rates of t heir t hermal degradation . The ra tes for polybu tadiene indicated an act iv:ttion energy of 60 kilocalories per mole. The copolym er had very high init ial rates of degradation, followed by a rapid cirop, so t hat it wa~ not possible to obtain a reliab le activation energy. Polyacrylonitrile and a copolymer consisting of 31 percent of acrylonitrile a nd 69 percent of butadiene were investigated with regard to t he nature and distribu t ion of volat ile products, as well as to t he rates of t he ir thermal degradation. The rates were very high in it ially, but dropped rapidly 50 t hat it was not possible to determine accurately t he activation energy. Thp, acrylonitrile-butadiene copolym r r s howed a rlecomposit ion pattern s imila r to t hat of polybutadiene. Here, too, t he acLivat ion energy could !lot be rlec!uced accurate ly from the rate curves. Comparati\Oe thermal ~tab ili ty in te rllls of temperatu re, at which half of the polymer sample is evaporated in 35 m inu tes of heating, is as follows: -!07°C for polybutadienc, 374°C for SBll, 36+° C for polystyrene, 360° C for NEll, and3JGo C for polyacr ylon itrile.