Flame retardant, combustion and thermal degradation properties of polypropylene composites treated with the mixture of pentaerythritol, nickel hydroxystannate and expandable graphite

Abstract

Spherical nickel hydroxystannate (NiSn(OH)6, NHS) particles were successfully prepared by a simple co-precipitation method and added into polypropylene (PP) matrix together with pentaerythritol (PER) and expandable graphite (EG). The flame-retardant, smoke suppressant and thermal degradation properties of PP composites were studied systematically. The results showed that the PP composite with 2phr PER, 28 phr EG and 2 phr NHS (PP/2PER/28EG/2NHS) passed the UL-94 V-0 level, and its total heat release and total smoke production were reduced by 87% and 99% when compared with those of the PP/2PER composite, and reduced by 30% and 67% when compared with those of the PP/2PER/30EG sample. The char residue of PP/2PER/28EG/2NHS composite is composed of the hexagonal Chaoite, rhombohedral graphite, SnO2 and a little NiO. 2 phr PER has no effect on promoting the char formation of PP; 30phr NHS could accelerate the decomposition and decrease the char formation of PP; 30phr EG could suppress the decomposition and promote the char formation of PP; 2PER/28EG/2NHS could promote the early thermal degradation, slow down the thermal degradation velocity of PP and results in a higher char formation.