THERMAL-STABILITY AND DEGRADATION OF HYDROCARBON METATHESIS POLYMERS

The thermal stability of poly(dicyclopentadiene), made with RuCl2(p-cy mene)(PCy3) as initiator, was investigated by ageing 2 and 5 mm plates up to 1 year at 180 degrees C in air, or 360 h in a weather-o-meter. The surface roughness and microhardness of unstabilized and stabilized (0.1% Irganox(R) 1520, 0.5% Tinuvin(R) 171) probes were determined. S tabilization leads to an overall softer material but with a harder sur face oxide layer with finer cracks, limiting the oxygen diffusion rate into the material and therefore protecting the underlaying material f rom fast oxidation. This is further supported by chemiluminescence (CL ) measurements of 50 and 150 mu m films of poly(DCPD) under strong oxi dative conditions (150 degrees C in pure O-2). It was found that even the unstabilized material is extremely resistant to oxidation, far sup erior to saturated poly(ru-olefins) like poly(propylene). Pyrolysis of poly(DCPD) and poly(cyclooctene) (Vestenamer(R)) at 670 degrees C und er an inert atmosphere gave mixtures of cyclic and open-chain unsatura ted hydrocarbons. Surprisingly, the pyrolysis of poly(norbornene) (Nor sorex(R)) gives squalene in > 90% yield. (C) 1998 Elsevier Science B.V . All rights reserved.