Thermomechanical behavior of a polynorbornadiene

A high‐temperature linear amorphous hydrocarbon polymer synthesized cationically from 2,5‐norbornadiene (bicyclo[2.2.1]hepta‐2,5‐diene), was studied thermomechanically with respect to physical transitions and stability in nitrogen. The glass transition temperature was determined to be 320°C (at less than 1 cps), which is probably the highest known for a linear hydrocarbon addition polymer. The thermomechanical technique of torsional braid analysis, together with thermogravimetric analysis, differential thermal analysis, infrared analysis, and solubility studies, was used to investigate the sequential events of the glass transition and degradation. The polymer is of particular interest since it is a high‐temperature plastic which in the bulk form would probably need to be processed at high speeds in the vicinity of Tg in an inert atmosphere. The presence of tertiary hydrogen atoms should render it amenable to degradation by the earth's environment.