Thermal stability and flammability of polyurethane foams chemically reinforced with POSS

Abstract

This work reports on the thermal stability and flammability of a novel class of rigid polyurethane foams chemically modified by functionalized 1,2-propanediolisobutyl POSS (PHI-POSS) as a pendant group and octa (3-hydroxy-3-methylbutyldimethylsiloxy) POSS (OCTA-POSS) as a chemical cross-link. The foamed hybrid materials were prepared in a three-step process using a sorbitol-based polyether polyol, polymeric 4,4 0 -diphenylmethane diisocyanate and dimethyl propane phosphonate as a flame retardant. The addition of the POSS modifier influences the PU cellular structure as evidenced by a change in anisotropy index of the cross section parallel to the growth direction. Based on thermogravimetric data and flammability results, one can suggest that there is char formation at the surface and the formed layer acts as an insulating barrier limiting heat and mass transfer with flame retardant and thus leading to decreased heat release rate, especially for systems containing OCTA-POSS.

Polyurethane composites based on silsesquioxane derivatives of different structures

“…In order to increase above-mentioned parameters of polyurethanes, different strategies can be applied. Thermal stability and flame retardancy of PU composites can be improved by incorporation of specific comonomers into the polymer backbone or by blending with fillers of different nature (silsesquioxanes, borax, graphite, carbon fillers, silicates, metals, graphene, phosphates, and many others) [42][43][44][45][46][47][48][49].…”

Preparation of poly(ethylene oxide) brush‐grafted multiwall carbon nanotubes and their effect on morphology and mechanical properties of rigid polyurethane foam

“…For SEM analysis, samples were mounted on aluminium studs using adhesive graphite tape and sputter‐coated with gold before analysis. The pore structure properties, such as average cell size, average cross‐section of cells and anisotropy index of cells, were determined using Image‐Pro Plus software …”

“…The pore structure properties, such as average cell size, average cross-section of cells and anisotropy index of cells, were determined using Image-Pro Plus software. 26,28 TGA was carried out using a TA Instruments 500. Temperature programs were run from 30 to 800 ∘ C at a heating rate of 10 ∘ C min −1 under a nitrogen atmosphere.…”

Mechanical, acoustic, and thermal performances of shear thickening fluid–filled rigid polyurethane foam composites: Effects of content of shear thickening fluid and particle size of silica

“…Therefore, studies on the effects of using various additives on the thermostability of PU foam have become popular in recent years. Michałowski et al . applied polyhedral oligomer silsesquioxane (POSS) modifier to improve the thermostability and flammability of rigid polyurethane foams, and they found that the cellular structure of the foam was dependent on the addition of POSS modifier.…”

“…8 Therefore, studies on the effects of using various additives on the thermostability of PU foam have become popular in recent years. Michałowski et al 9 applied polyhedral oligomer silsesquioxane (POSS) modifier to improve the thermostability and flammability of rigid polyurethane foams, and they found that the cellular structure of the foam was dependent on the addition of POSS modifier. Zheng et al 10 used a one-step method to make PU foams using microwave liquefied sugar beet pulp (LSBP) and polymethylene polyphenyl isocyanate, examining the influence of the NCO─/OH─ ratio on the mechanical, thermal, and microstructural properties of LSBP/PU foam.…”