1,2-Propanediolizobutyl POSS as a co-flame retardant for rigid polyurethane foams

Abstract

Polyurethane (PU) foams physically modified by two additive phosphorous flame retardants (FR)—phenol isobutylenated phosphate or phenol isopropylated phosphate, and chemically reinforced by functionalized 1,2-propanediolizobutyl POSS (PHI-POSS) have been synthesized and investigated towards thermal and mechanical properties, as well as flammability behaviour. The foamed PU hybrid materials were prepared in a two-step process using a polyether polyol and polymeric 4,4′-diphenylmethane diisocyanate. On the basis of the obtained results of mechanical properties, thermal insulation, thermal stability and flammability investigations, the influence of the applied additives—including POSS nanoparticles, on the rigid polyurethane foams was determined. The analysis of thermogravimetric and microcalorimetry data revealed an improved resistance to burning of the PU foams containing hybrid reactive (POSS)/additive (phosphate) FR systems, as evidenced by reduced rate of heat release. Importantly, mechanical properties tests showed that incorporation of bulky silsesquioxane nanoparticles to polyurethane structure via covalent bonds strengthens the foam integrity.