The thermal degradation of poly‐p‐xylylene

The thermal stability of poly‐p‐xylylene prepared in solution by the Hofmann reaction has been measured by a viscometric method. The polymer decomposes by a first‐order random cleavage mechanism with an activation energy of 58 kcal./mole. The latter value is identified with the bond strength of the carbon‐carbon bond between methylene groups connecting benzene rings. The stability of this polymer is thus limited only by the strength of the weakest link along the chain. The polymer is shown to be more stable thermally and more soluble than polymer prepared from p‐xylene by the pyrolytic method. The effect of chain transfer agents on the thermal stability was investigated.