Exploring Soybean Oil-Based Polyol and the Effect of Non-halogenated Flame Retardants in Rigid Polyurethane Foam

To address the increasing demand for sustainable biomaterials because of the excessive usage of fossil fuel and growing concerns with the environment, a novel biodegradable and environmentally friendly rigid polyurethane foam (RPUF) has been synthesized. These foams are derived from chemically modified soybean oil-based polyol (SBO-polyol) obtained through the formation of oxirane followed by the opening of the oxirane reaction. Polyurethane foam is generally used in construction, furniture, and automobile industries but is highly flammable and releases toxic fumes in combustion. In this study, an efficient synergistic effect of non-halogen flame-retardant (FR) melamine salt, 2-carboxyethyl(phenyl)phosphinic acid melamine salt (CMA) was synthesized from 2-carboxyethyl(phenyl)phosphinic acid (CEPP) and melamine (MA). Fourier transform infrared (FT-IR) spectroscopy characterized the chemical structure of CMA. Three different FRs, MA, melamine cyanurate (MC), and CMA were separately introduced in increasing quantities for the foam preparation to suppress the flame during combustion. The influence of these FRs on the thermal properties, flame retardancy, morphology, physical, and mechanical properties of the prepared RPUFs was studied through closed cell content, apparent density, compression test, horizontal burning test, thermogravimetric analysis (TGA), and gel permeation chromatography (GPC), scanning electron microscopy (SEM). The addition of 28.56 wt% of MA (MA-15), MC (MC-15), and CMA (CMA-15) presented a burning time of 10.1 s with weight loss of 5.34% and 28.4 s with 13.02% and 15.25 s with 8%, respectively. The findings demonstrated that all three FRs gave RPUF good FR properties.