writer：Jie Li，Xuehua Mo, Yi Li, Huawei Zou, Mei Liang, Yang Chen
keywords：Semi-rigid polyurethane foam, Expandable graphite particle size, Ammonium polyphosphate, Synergistic flame retardant effect
source：期刊
specific source：Polymer Bulletin, 2018,75(11): 5287-5304.
Issue time：2018年

ABSTRACT: Effect of the difference of expandable graphite (EG) particle size on the  synergistic flame retardant effect between expandable graphite (EG) and ammonium polyphosphate (APP) in the semi-rigid polyurethane foam (SPUF) was studied for the first time. Three large-span particle sizes of EG were added into SPUF with different mass ratios of EG/APP. The synergistic effect between EG and APP on the flame retardant property of composites was investigated using the limiting oxygen index test, horizontal–vertical burning test, thermogravimetric analysis (TGA), scanning electron microscope (SEM), etc. Flammability performance tests indicated that the larger particle size the EG possessed, the more obvious will be the synergistic effect exhibited between EG and APP. SEM images and TGA results provided positive evidence for the combustion tests. Synergistic effect was strongly influenced

by the compactness of united protective layer. The maximal rate of the degradation of the SPUF composite system further confirmed the relationship between the rate of the composites’ degradation and the compactness of united protective layer. Speculative reactions which were related to the changes of EG in the presence of APP under high temperature were discussed.