Silane-functionalized Flame-retardant Aluminum Trihydroxide in Flexible Polyurethane Foam

Abstract

Flexible polyurethane (PU) foams are easily ignitable and show a high burning velocity, mainly due to their high surface area-to-mass ratio and high air permeability. Consequently, flame retardants such as halogenated compounds are applied. However, the use of halogenated flame retardants is not considered beneficial in transport applications, for example, aviation or automobile, in part due to the high smoke generation. Solid nonhalogenated flame retardants, for example, aluminum trihydroxide (ATH), are known as smoke suppressants. The application of ATH in flexible (PU) foam has not yet been reported in the literature. In this study, the application of different types and amounts of ATH and the resulting structure—property relationship in the foam are investigated. The increase in the viscosity of the filled raw materials during the foaming process and the negative effects of the filler on the mechanical properties of the final foam pose particular problems in the application of ATH. To pass the FMVSS 302 test, high amounts of ATH are necessary. To overcome the mentioned drawbacks, ATH particles are functionalized by 3-aminopropyltriethoxysilane under different conditions. The synthesized products were characterized by Fourier transform infrared, energy-dispersive X-ray fluorescence analysis, and 29Si and 1H solid-state nuclear magnetic resonance spectroscopy. The silane-treated ATH particles show a significant decrease in viscosity of the ATH—polyol system of more than 20% at ATH contents of up to 60 phpp. Values of the rising behavior during foaming and the burning velocity are not affected by this silane treatment. However, the compression test of PU foams with the silane-treated ATH particles show a decrease in compression strength of up to 20% compared to untreated ATH particles in the flexible PU foam. At higher ATH contents, no effect of silanization is observed.

Characterization of rigid polyurethane foams containing microencapsulted phase change materials: Microcapsules type effect

“…This effect can be explained by the increase in the foaming system viscosity caused by the presence of the fillers,24, 27 the nucleation effect of the microcapsules,27 the higher amount of mass that has to be lifted by the same expanding gas generated during the foaming process, and by its less cell expansion 24. The lower cell expansion is attributed to the absorption by the PCM of part of the heat released during the chemical reactions of this process what decreases the reaction temperature and reduces the expansion volume of the CO 2 cell gas 24. On the other hand, Figure 9 shows a comparison of the final heights and foaming rates of these two microcapsules types with those obtained with mSD‐(LDPE·EVA‐RT27).…”

“…Similar results were reported by Javni et al22 who observed that Cloisite Na + (natural montmorillonite) and nano‐silica with a hydrophilic surface increased hardness and compression strength of the foams, whereas Cloisite_10A modified with a quaternary ammonium salt decreased the modulus, hardness, and compression strength. Additionally, results reported by Cao et al,23 König et al,24 and Harikrishnan et al25 indicated that other fillers such as organically modified montmorillonite, aluminum trihydroxide particles, or carbon nanofibers increased the compression strength of polyurethane foams.…”

Highly flame retardant and bio‐based rigid polyurethane foams derived from orange peel oil

“…Flame retardant polyurethanes foams have been prepared by addition of various flame retardant compounds such as compounds containing phosphorus and/or nitrogen groups, expendable graphite, MgO, and Al 2 O 3 . It was observed that expandable graphite and nitrogen‐based derivatives require higher loading as additive to achieve decent flame retardancy .…”

Castor‐oil derived nonhalogenated reactive flame‐retardant‐based polyurethane foams with significant reduced heat release rate

“…The addition of FR polyol showed no significant change in the compressive strengths of the foams [Figure (b)]. Usually, AFRs such as dimethyl methyl phosphonate (DMMP), 2,2‐diethyl‐1,3‐propanediol phosphoryl melamine (DPPM), melamine, and expandable graphene tend to adversely affect the compressive strength of the foams . In fact, the addition of MCO–DEAP polyol showed slightly improved compressive strength of the foams .…”