Flexible polyurethane (PU) foams are widely used in many industrial applications, such as upholstered furniture and mattresses, automotive applications, etc. The chemical nature of the PU, the high air permeability, and the high inner surface area of the foam structure cause this material to be highly flammable. Consequently, the application of flame retardants to flexible PU foams is an important issue. The use of halogenated flame retardants is not considered optimal, in part due to the high emission level and the possible phase-out by the European Risk Assessment Body. Consequently, melamine as a nonhalogenated flame retardant is applied more and more frequently. However, little data is available regarding the application of melamine as an additive in flexible PU. This paper is concerned with the influence of melamine on the synthesis of the PU foam and the resulting material-specific properties. Especially, the increase of viscosity and the high heat capacity of melamine lead to a decrease in foaming growth and rising height with increasing melamine content. This is caused by the reduced drainage rate between the struts and the plateau borders in the foam-forming process. Here, the increase in viscosity follows the Dougherty—Krieger equation with the intrinsic viscosity of k = 3.3. The mechanical properties such as density and compression strength increase with increasing melamine content. Other properties like tensile strength and elongation decrease because of the embedding of the melamine in the PU matrix, which weakens the structure. The air permeation and number of cells also decreases because of the thickened struts caused by the reduced drainage rate in the foaming process. Furthermore, the reaction between the amino groups of melamine and the isocyanate of the PU formulation was investigated by FTIR.

We present a study of dispersion polymerization of methyl methacrylate in supercritical CO 2 (sc-CO2) at 330 bar in situ by turbidimetry. All experiments have been done in the presence of the macromonomer poly(dimethylsiloxane)-monomethacrylate (PDMS-MA) which acts as a stabilizer. The formation of particles of poly(methyl methacrylate) (PMMA) can be monitored quantitatively by turbidimetry because the degree of swelling by sc-CO2 as well as the refractive index of these particles is known accurately. The turbidity spectra were measured in the range 400-950 nm. The number density N/V and the diameter στ could be obtained as a function of time in the earliest stage of the dispersion polymerization with a time resolution of ca. 0.1 s. Moreover, the mass of polymer mp(t) could be deduced by means of which a full kinetic analysis could be performed. Special attention has been paid to the size distribution of particles that is shown to play an essential role in the treatment of turbidimetric data. It is demonstrated that the locus of polymerization in the early stage studied here is the homogeneous phase. N/V(t) raises quickly in the nucleation period (stage I) and remains then constant (stage II). The diameter of the critical nuclei, i.e., σ τ, measured in stage I is ca. 150-170 nm. All data obtained are in semiquantitative agreement with the model proposed by Paine.

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Due to their low density, high surface-to-mass ratio, high air permeability and open cell structure, slabstock polyurethane foams ignite easily and have a high burning velocity. In this study, the decomposition behavior of melamine in both an inert and an oxygen atmosphere has been investigated. TGA/DSC and EGA-IR experiments revealed the decomposition steps and products in inert and oxygen atmospheres, respectively. Cone calorimeter, NIR-flame characterization and small-scale burner test results showed that the excellent working mechanism of melamine as a flame retardant mainly depends on the formation of an effective closed char layer, which may involve condensation of melamine to form melam, melem, and related products as well as reactions of the amino and isocyanato groups forming urea derivatives, and the sublimation of melamine at the exact temperature at which TDI release occurs.

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.

Polyurethane (PU) foams were protected by phosphorous and nitrogen-based molecular flame retardant hexamethoxycyclotriphosphazene c-[N=P(OMe)2]3 (HMCPT). This compound was synthesized, analyzed, and investigated with respect to its thermal behavior, compatibility, and efficiency as a flame retardant (FR) for PU foams. The decomposition of HMCPT starts at 186°C in air and under argon, as indicated by TG/DSC measurements. It was possible to introduce 5 per hundred parts polyol (phpp) of HMCPT into the PU foams. The mechanical and morphological characteristics of the protected foams-compression load deflection, tenacity, tensile elongation, air perviousness, and raw density-were investigated indicating that the FR has an impact on all of these properties. The flame retardancy was evaluated with the FM VSS 302 test, where an self-extinguishing classification was reached with 5phpp of HMCPT. Cone calorimeter measurements provide evidence for a flame poisoning mechanism