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Expanded polystyrene (EPS) has excellent thermal insulation properties and is widely applied in building energy conservation. However, these thermal insulation materials have caused numerous fires because of flammability. Pyrolysis is necessary to support combustion, and more attention should be paid to the pyrolysis characteristics of EPS. Moreover, pyrolysis is considered to be an effective method for recycling solid waste. Pyrolysis kinetics of EPS were analyzed by thermogravimetric experiments, both in nitrogen and air atmospheres. A new method was proposed to couple the Flynn–Wall–Ozawa model-free method and the model-fitting method called the Coats–Redfern as well as the particle swarm optimization (PSO) global algorithm to establish reaction mechanisms and their corresponding kinetic parameters. It was found that the pyrolysis temperature of EPS was concentrated at 525–800 K. The activation energy of EPS in nitrogen was about 163 kJ/mol, which was higher than that in air (109.63 kJ/mol). Furthermore, coupled with Coats–Redfern method, reaction functions g(α) = 1 − (1 − α)3 and g(α) = 1 − (1 − α)1/4 should be responsible for nitrogen and air reactions, respectively. The PSO algorithm was applied to compute detailed pyrolysis kinetic parameters. Kinetic parameters could be used in further large-scale fire simulation and provide guidance for reactor design. [ABSTRACT FROM AUTHOR]

Thermoplastic polymers are versatile for different fields, and their waste is produced largely. Among the waste treatment methods, pyrolysis is an important method to dispose of thermoplastic polymers waste because of potential energy utilization. Furthermore, accurate pyrolysis kinetic parameters can reflect the pyrolysis process. Therein, reaction order n is an essential factor to characterize reaction kinetics, while the difference between different n values is very small, so the accuracy of n should be paid more attention. To obtain the accurate n value of thermoplastic polymers waste in nitrogen, one representative material called extruded polystyrene (XPS) was studied by using thermogravimetric analysis at five heating rates. The kinetic parameters and thermodynamic parameters were calculated simultaneously, and n was estimated by multiple methods (master plots, model-free, Shuffled Complex Evolution (SCE) and model reconstruction) at heating rates of 10, 30 and 40 K/min. The results showed that XPS waste had important energy potentials, and the n was 2, 2.08, 1.99 and 1.64 for four methods, respectively. Moreover, based on fixed kinetic parameters, the accuracy of n obtained by multiple methods was compared at 3 and 80 K/min not used to estimate kinetic parameters. The accuracy of these methods was: SCE > model reconstruction > model-free > master plots. • The kinetics and thermodynamic parameters are analyzed simultaneously. • The accuracy of reaction order estimated by multiple methods is compared. • The Shuffled Complex Evolution (SCE) method has the highest accuracy. • Two biomass materials are used to validate the high accuracy of the SCE method. [ABSTRACT FROM AUTHOR]