Fire-Retardant Synergy of Tris(1-Methoxy-2,2,6,6-Tetramethyl-4-Piperidinyl)Phosphite and Melamine Hydrobromide/Aluminum Diethylphosphinate in Polypropylene

Key Words:FLAME RETARDANCY; ALUMINUM PHOSPHINATE; HINDERED AMINE; COMBINATION; DEGRADATION; MECHANISMS; CYANURATE

Abstract:The fire-retardant synergy of tris(1-methoxy-2,2,6,6-tetramethyl-4-piperidinyl)-phosphite (NORPM) and melamine hydrobromide (MHB)/aluminum diethylphosphinate (ADEP) in polypropylene (PP) was characterized by UL-94 tests, limiting oxygen index (LOI) determination and cone calorimetry tests (CCT). NORPM exhibits an exceptional synergy in PP. The LOI and fire-retardant effectivity (EFF) of S-3 (the loadings of MHB and ADEP 1.00 and 1.50 wt%, respectively, no NORPM) were 19.0% and 0.48%, respectively, however, the LOI and EFF of S-15 (the loadings of NORPM, MHB and ADEP 0.2, 1.00 and 1.50 wt%, respectively) significantly increased to 25.5% and 2.85%, respectively, synergistic effectivity (SE) of NORPM is 2.03, and the fire-retardant rating was improved from none to UL 94 V-2 and the total heat release (THR) and peak heat release rate (PHRR) dropped obviously by adding the 0.2 wt% NORPM. The analysis by thermogravimetry-mass spectrum analysis (TG-MS) of the PP samples and the residues in the CCT revealed that NORPM, MHB and ADEP induced the synergy primarily by the following modes: CH3O center dot, aminyl radicals, CH3 center dot and nitro radicals formed through the cracking of NORPM, along with the free radicals such as PO center dot, PO2 center dot and HPO center dot pyrolyzed from ADEP and HBr from MHB, which quenched the active radicals, such as HO center dot, H center dot, ROO center dot, R center dot and broke down the radical source. The chain oxidation reaction of combustion was accordingly interrupted, which brought about the more exceptional fire-retardant effect than that of MHB/ADEP.

Volume:61

Issue:2

Translation or Not:no