Multistep kinetic analysis of additive-enhanced plastic degradation

In the realm of non-isothermal degradation kinetics, the utilization of multi-heating rate data has unveiled a fascinating distributed apparent activation energy (E_α) profile when employing isoconversional methods. The advanced isoconversional method (AIC) emerges as a reliable tool, offering E_α values that evolve as chemical reactions progresses. This phenomenon finds its roots in the complex solid-state degradation of plastics, where long-chain hydrocarbons undergo intricate transformations into smaller components through a web of parallel and sequential reactions under the influence of heat. To comprehensively characterize this multifaceted kinetic process, variable pre-exponential factor (A) values were calculated, considering all available heating rate data, in conjunction with the isoconversional principle. These factors complement the changing E_α values, providing crucial insights into the evolving material transformations throughout the reaction. Remarkably, our investigation revealed that in the initial degradation stage, centered around the breakdown of Brominated Flame Retardant (BFR), the reaction follows a contracting spherical model (R3). Transitioning to the subsequent stage, the polymer material undergoes degradation following the diffusion model D4. The incorporation of the isoconversional principle and Criados' masterplot technique effectively facilitates the precise determination of all three kinetic parameters. The process layout we present holds considerable promise for advancing the understanding and control of complex kinetic phenomena.