On the kinetics and mechanism of thermal degradation of polystyrene

Abstract

The thermal degradation of polydisperse polystyrene samples with mol. wts. (3,) between 6OOOO and 220000 has been investigated at different temperatures under oxygen free conditions. Product analysis has been carried out by GPC. The experimental degradation could be simulated by a model consisting of scission and depolymerization. The dynamical behaviour of this model is expressed in a matrix form. The ratio of scission and depolymerization is constant for all polymers and different temperatures during degradation. Therefore, a master curve could be evaluated, which gives a general relation between the decrease of mol. wt. and the mass of volatiles. Finally a radical chain mechanism has been proposed in a lumped form which is consistent with the kinetic model and the experimental results. 0025-1 16X/82/05 1207-12/%03.00

Detailed kinetic modeling of the thermal degradation of vinyl polymers

“…A further possible reduction of the overall dimension of the problem can be addressed with appropriate lumping procedures [41]. This approach is equivalent to the discrete sectional model, which has been widely adopted in particle distribution research for many years [42,43].…”

Polymer chain in a quenched random medium: slow dynamics and ergodicity breaking

“…In the mean time it is well known [14,18,20,22,23] that the renormalization group (RG) consideration for the discussed problem suffers from he lack of a stable fixed point for the renormalized second moment ∆ R , so that the perturbation theory can not be used. Nevertheless, it was argued [22,23,24] that for the weak disorder in the thermodynamical limit the quenched and annealed averaging lead to the same results. The authors of ref.…”

“…A large number of theoretical studies emphasizing the statical [10,11,12,13,14,15,16,17,18,19] and dynamical [12,20,21,22,23,24,25,26] aspects of the problem. When discussing the static properties one should discriminate between the annealed and quenched averaging.…”

Thermal Pyrolysis of Polystyrene Aided by a Nitroxide End-Functionality. Experiments and Modeling

“…At higher temperatures (600 and 700 • C), increased production of benzene, toluene, ethylbenzene, and α-methyl styrene and decreased production of styrene have been observed, probably due to the predominance of intramolecular hydrogen transfer reactions at this range of temperatures [18]. Concerning termination, some authors propose a mechanism involving the recombination [9,11], or the disproportionation reaction [19] between two radicals; while others suggest the occurrence of depropagation until the end of the polymer molecule [13].Published studies related to the thermal degradation and pyrolysis of polystyrene [13,[20][21][22][23][24][25] have been performed in a variety of reaction systems and sets of conditions, including reaction temperatures, reaction times, and molecular weights of the polystyrene sample, resulting in a broad collection of reaction yields and product distribution. The available reported experimental data fall into three types: chemical nature of the products (that help to elucidate the degradation mechanism), rate of evolution of products, and the change of molecular weight in the residue.Jellinek [22] reported experiments carried out in long open-to-air tubes containing 0.1 to 0.5 g of material, to show the influence of oxygen on the thermal degradation of polystyrene.…”