Characterization of styrene–butadiene copolymers by catalytic pyrolysis over Al-MCM-41

Abstract

In this work, the Al-MCM-41 catalytic pyrolysis of styrene–butadiene copolymers in a thermobalance has been studied. The behaviour of such copolymers and the corresponding to high impact polystyrene (HIPS), physical blend of PS and PB with a given grafting degree, has been compared, and the importance of the degree of contact between the catalyst and the different polymer domains has been pointed out. Different particle size copolymer particles have been mixed with the catalyst, and in addition, samples have been prepared by solving the copolymer and mixing it with the catalyst, thus assuring an intimate contact. Different decomposition steps which can be related to the degradation of the different domains of the copolymer (polystyrene (PS) and polybutadiene (PB)) have been observed, despite the decomposition processes of the PB and PS domains are not completely independent, showing certain interaction. The importance of to carefully controlling, defining and characterizing the experimental conditions of catalytic pyrolysis of PS–PB experiments in order to generalize or to extend the results obtained in such experiments is clearly demonstrated, and pseudokinetic models capable of reproducing the amount of material evolving trough each decomposition step have been suggested. The possibility of combining the two criteria: (1) the assignment of each decomposition step and (2) the application of a pseudokinetic model is suggested as a potential tool for the characterization of the composition of commercial copolymers or mixtures of PB and PS, once the adequate calibration runs have been performed.