RECOVERY OF HIGH-VALUED PRODUCTS FROM STYRENE-BASED POLYMERS THROUGH COPROCESSING - EXPERIMENTS AND MECHANISTIC MODELING

The recent emergence of pyrolysis as a viable resource recovery strate gy has focused attention on understanding the complex chemistry underl ying the decomposition processes. In this work, a quantitative link be tween measurable experimental changes and kinetics analysis was establ ished to explain the behavior of styrene-based polymers alone and in b inary mixtures during pyrolysis. Experiments with low molecular weight polystyrene and poly(alpha-methylstyrene) were carried out which show ed that a higher selectivity to monomer was obtained for poly(alpha-me thylstyrene) than for polystyrene. The binary mixture experiments reve aled that the reactivity of polystyrene was enhanced in the presence o f poly(alpha-methylstyrene), and the selectivity to styrene monomer wa s increased. Overall, the experimental results suggest that coprocessi ng is a viable polymer resource recovery strategy when the addition of an appropriate co-reactant is used to tailor the product distribution . Furthermore, novel polymer structures may be designed to promote deg radation to high-valued products. The experimental results were interp reted using a detailed mechanistic model which described the reactions of alpha-methylstyrene and styrene trimers and was generated using so ftware for automated model construction to describe 901 species using over 4000 reactions. By exploiting the capability to label the model r eactants, a quantitative link between polymers and their mimics was es tablished and probed the impact of the kinetic coupling between differ ent polymers. (C) 1998 Elsevier Science B.V.