Synchrotron small-angle X-ray scattering study of flame retardants based on ammonium sulfate and disubstituted ammonium phosphate

Abstract

The use of wood in structural and finishing materials can significantly reduce the time of building construction, but the high flammability of wood limits its use in the building industry. To increase fire resistance, wooden structures are impregnated with flame retardants and the penetrating ability depends on their structure. We present the results of a small-angle X-ray scattering study of the structure of flame retardants based on ammonium sulfate and phosphate. The radii of inertia of hydrated complexes formed when flame retardants are dissolved in water, their shape and type of chains along which hydrated ions are located are determined. It is revealed that the presence of diffraction maxima indicates the presence of an ordering in the arrangement of hydrated ions. Aqueous solutions of ammonium sulfate and disubstituted ammonium phosphate contain two types of hydrated complexes of the same shape but different radius of inertia. At the same time, hydrated ions in complexes are located along persistent chains, and ordering revealed in the arrangement of ions, depended on their type. The results obtained can be used in developing flame retardants with a reduced radius of inertia, which will increase the penetrating capacity of the processing solution and increase the fire safety of wooden structures.