Effective Halogen- and Phosphorus-Free Polyphenylene Ether Resin-Based Flame-Retardant Foam

Abstract

A novel halogen- and phosphorus-free intrinsic flame-retardant foam is fabricated from curable phenol-terminated polyphenylene ether resin with a high molecular weight using phenol, formaldehyde, and diphenyl ether as starting materials. The limiting oxygen index (LOI) of the pure foam is 24.90% ± 0.28. When 0.5 wt % silica sol is added, the LOI of the foam (SPF-0.5) is up to 28.5% ± 0.15 and both the combustion heat release rate and total combustion heat are low. Moreover, the SPF-0.5 foam exhibits high carbon residue, high compressive strength, and low pulverization rate and is superior to some previously reported phenolic foam. The flame-retardant mechanism includes the condensed-phase flame retardation and the gas-phase flame retardation, with the former being the main step, which is based on the high cross-linking density, the higher strength and smaller size of foam cells, and the formation of a carbon–silicon compound in the foam. This halogen- and phosphorous-free flame-retardant foam is also environmentally benign.

Study of preparation and properties of environmentally friendly phenolic resin for mining

“…It can be found that the limiting oxygen index of PF and PUF were the same, while PAF improves the limiting oxygen index and the flame retardant performance of PF. Compared with a novel halogen and phosphorus‐free intrinsic flame‐retardant foam made by Li et al, the limiting oxygen index of PAF is increased by 48.60% 67 . The reason is that ammonium chloride acts as a halogen flame retardant.…”

“…Compared with a novel halogen and phosphorus-free intrinsic flame-retardant foam made by Li et al, the limiting oxygen index of PAF is increased by 48.60%. 67 The reason is that ammonium chloride acts as a halogen flame retardant. In the case of high temperature or burning, the hydrogen chloride gas generated by the decomposition of ammonium chloride eliminates the active free radicals generated by the combustion of PF.…”