Thermal oxidation of Poly(dicyclopentadiene)– kinetic modeling of double bond consumption

Abstract

This paper reports chemical changes that occur in polydicyclopentadiene during thermal oxidation at several temperatures and oxygen pressures. A particular attention was paid to the double bond consumption since these latter are associated with crosslinking and subsequent changes in mechanical properties. A kinetic model was derived from the experimental results. Its rate constants were assessed from the "inverse approach" based on their selective identification under specific ageing conditions (for example under oxygen excess). The resulting model satisfactorily describes both carbonyl formation and double bond consumption for a wide range of temperature and oxygen pressure for the first time. This can be exploited to predict the changes of local mechanical properties.

Impact of thermal oxidation on mechanical behavior of polydicylopentadiene: Case of non-diffusion limited oxidation

“…Details about curing conditions are available in Ref. [10]. Samples were stabilized with 0.0226 mol l À1 butylated hydroxytoluene.…”

“…[15] At the same time, a decrease of the band situated at 1650 cm À1 and attributed to the double bond in the polymer is observed, see Ref. [10] for details. All these observations are in accordance with existing knowledge on oxidation of pDCPD [1e13,16].…”

“…Where TOL is the thickness of oxidized layer, D O2 the oxygen diffusivity and equal to 8.10 À8 cm 2 s À1 at 25 C with an activation energy of 15 kJ mol À1 , [O 2 ] the oxygen concentration (calculated with a solubility of 10 À7 mol L À1 Pa À1 ) and Vox the value of oxidation rate from FTIR [10].…”

“…Second, pDCDP has a large number of double bonds within its backbone (up to 13 mol/L see Ref. [10]) that affect oxidation mechanisms. In fact, in the presence of double bonds, radicals react directly with these double bonds during the propagation step [10].…”

“…[10]) that affect oxidation mechanisms. In fact, in the presence of double bonds, radicals react directly with these double bonds during the propagation step [10]. This reaction leads to the formation of a new chemical bond and so an increase in the crosslink density of the polymer.…”