Invariant kinetic parameters of polymer thermolysis. IV. Influence of fire‐retardant additives on polypropylene thermolysis

Abstract

AbstractAnalyzing the transformation‐degree dependence of the effective activation energy, we have studied the thermolysis gross kinetics of polypropylene (PP)‐based fire‐resisting composition and a synergetic mixture of fire‐retardant additives: antimony oxide and hexabrominecyclododecane (HBCD). The addition to PP of individual HBCD and in a mixture with antimony oxide increases the activation energy at the initial stage of thermolysis, which is attributed to the ability of fire‐retardant additives to impede destruction initiated by oxidation. The investigation of the process proceeding in PP prior to the onset of decomposition in the presence of fire‐retardant additives has shown that these additives stimulated crosslinking of polymer chains. The addition to PP synergetic mixture gives the greatest—compared to its individual components—content of the crosslinked fraction (10%), whose presence is likely to inhibit the proceeding of thermolysis by the oxidation mechanism.