Polymer reactions, 8. Oxidative pyrolysis of poly(propylene)

Abstract

Poly(propy1ene) has been oxidized at temperatures between 240 and 289 "C. The products were GC separated and on-line identified by an interfaced GC peak identification system. The major products are CO,, H,O, acetaldehyde, acetone, butanal, formaldehyde, methanol and other ketones and aldehydes. Most of the products can be accounted for by well-known reactions of alkoxyl and peroxyl radicals; the major products are derived from the secondary alkoxy and peroxy species. Oxygen starvation is manifested in diffusion limited products of olefins and dienes, and the increase of CO, and H 2 0 formation in pure oxygen atmosphere. The first order rate constant at 240°C is 2,4.10-3 s-' with an overall activation energy of ca. 16 kcal.mo1-' (67 kJ.mol-'). If one assumes the oxidative pyrolysis to share the same reaction pathways as autoxidation at lower temperatures, then the observed rate constants and activation energy may be calculated from kinetic parameters measured earlier for autoxidation of poly(propy1ene) from 71 to 140°C. Good agreement was obtained implying a similarity of oxidative degradation of the polymers spanning a large temperature range.

Thermal and fire degradation of recycled and polluted polypropylene‐based materials

“…Reaction 3 could be assigned to the molecular decomposition of hydroperoxides. The activation energy of this reaction is around 67–72 kJ/mol29–31 and is close to our values. Reactions 2 and 4 can be assigned to char oxidation reactions.…”

Thermal oxidation of polypropylene in the temperature range of 120–280°c

“…Oxygen deficiency has also been observed during pyrolysis of PP at 240-289°C. 17 A comparison of the gas chromatograms of the volatiles formed on oxidation of PP at 280°C, at 12OOC and on the thermal decomposition of the preoxidized polymer is shown in Figure 4.…”

Kinetics of the Thermal and Thermo-Oxidative Degradation of Polystyrene, Polyethylene and Poly(propylene)

“…Factor-jump TGA [19] PP Ar 98, 328 c) Nonisothermal TGA [25] PP Air 67 Nonisothermal TGA [18,21] PP Air 102 Nonisothermal TGA [22] PP Air 72 Isothermal TGA [24] PP Air 80-190 b) Nonisothermal TGA [19] PS N 2 204 Isothermal TGA [11] PS N 2 250 Nonisothermal TGA [33] PS N 2 203-218 d) Nonisothermal TGA [34] PS N 2 220, 277, 187 a) Nonisothermal TGA [34] PS N 2 and vacuum 188…”