Synthesis and characterization of phosphorus and boron containing flame retardant rigid polyurethane foam

Abstract

Polyurethane materials were scientifically demonstrated through the polymerisation system between diisocyanate and diols with the discovery of Otto Bayer. Polyurethane materials, which have a wide range of products, are frequently encountered in daily life. The industries it serves are based on flooring, automotive, aerospace, construction-insulation, and CASE industry. Industrial product groups of polyurethane foams consist of flexible and rigid polyurethane foams. This study focuses on rigid polyurethane foam materials. These materials are materials that can easily combust in the ambient atmosphere due to their organic structure as well as the excellent strength feature they have by nature. Flame retardant additives added to the structure are aimed to minimise the effects of the fire scenario. Flame retardant technology is one of the widely researched topics in the literature. The content of flame retardants is very critical when considering the environmental effects after combustion. Toxic chemicals (especially halogen-containing structures) in the flame retardant content during the smoke release after combustion cause adverse effects on human and environmental health. The TDB flame retardant structure synthesized in this study is halogen-free and based on the synergistic effects of phosphorus, nitrogen and boron. TDB was designed as a flame retardant by synthesising THEIC containing triazine-trione ring in two steps by means of esterification reaction of boric acid and DPCP. TDB flame retardant synthesised for use in the formulation of rigid polyurethane foams was loaded at chemical compositions of 5%, 10%, 15% according to polyol. Rigid polyurethane foams prepared by one shot free rise method were blown in moulds for characterisation tests. In addition to the flame retardant properties of flame retardant TDB, the morphological structure, mechanical properties, thermal insulation ability and thermal stability of foam cells were investigated. Flame retardancy profile, LOI and Cone calorimeter tests show that the flame retardancy profile of the foams containing 10% TDB is improved compared to neat RPUF. LOI value reached from 18,8% to 20,8%. It is proved by cone calorimeter test results that the total heat release rate decreases with the effect of TDB content. In this context, in line with the characterisation tests, TDB is considered to be a flame retardant compatible with the structure of RPUF.