A semi-global reaction mechanism for the thermal decomposition of low-density polyethylene blended with ammonium polyphosphate and pentaerythritol. (October 2022)

• Record Type: Journal Article
• Authors: Coimbra, Alain; Sarazin, Johan; Bourbigot, Serge; Legros, Guillaume; Consalvi, Jean-Louis
• Is Part Of: Fire safety journal. Volume 133(2022)
• Publication Date: 2022-10
• Subjects: 00-01 -- 99-00; Thermal analysis -- Intumescence -- LDPE -- APP/PER -- Material flammability; Fire prevention -- Periodicals; Incendies -- Prévention -- Recherche -- Périodiques; Fire prevention -- Research; Periodicals; 628.92205
• DOI: 10.1016/j.firesaf.2022.103649
• Languages: English
• ISSNs: 0379-7112

Abstract

Abstract: A semi-global reaction mechanism has been developed to capture the decomposition of a polymer, i.e. low-density polyethylene (LDPE) that contains a condensed-phase-active intumescent flame retardant, i.e. ammonium polyphosphate (APP) mixed with pentaerythritol (PER) with ratio 3:1 (wt/wt). The methodology combines thermogravimetric analysis (TGA) in anaerobic environment over a wide range of heating rates and inverse modeling of these experiments based on the Shuffled Complex Evolution (SCE) optimization algorithm. The decomposition of neat LDPE can be described by a single first-order reaction. In contrast, the decomposition of the APP/PER additive is characterized by strong interactions between the reactants and a 5-step reaction mechanism was designed driven by the mechanisms of the intumescence process. The direct coupling of the 1-step reaction mechanism for LDPE and the 5-step reaction mechanism for APP/PER was found to provide decent predictions for the decomposition of the 90%LDPE/10% APP/PER blend. The slight interactions between the LDPE matrix and the APP/PER additive were taken into account by updating the kinetic parameters of two reactions, leading to a final robust and accurate 6-step reaction model.