A Novel Elastic Urea–Melamine–Formaldehyde Foam: Structure and Properties

Abstract

Melamine was chemically introduced into a urea−formaldehyde system via co-condensation reactions during curing and foaming process, and a novel elastic urea− melamine−formaldehyde (UMF) foam with improved thermal stability, insulation property, and flame retardancy was fabricated. It was found that with a decrease of the mass ratio of urea formaldehyde resin and melamine formaldehyde resin (UF/MF), the curing process of UMF was prolonged, and a high curing temperature was necessary. The UMF foam exhibited an interconnected network structure with increasing cell size and size distribution, higher open cell porosity, and lower apparent density compared with pure UF foam. Evident recoverable deformation can be observed for UMF foam during the compression testing, which was resulted from the elasticity and toughness. By addition of melamine, the thermal conductivity decreased, while the decomposition temperature, char yield, and LOI increased, and during burning, the expansion of the flame was suppressed. With increasing content of MF resin, the sound absorption coefficient increased at first and then declined.

Preparation and adsorption mechanism of polyvinyl alcohol/graphene oxide‐sodium alginate nanocomposite hydrogel with high Pb(II) adsorption capacity

“…The pore size distributions of PVA/GO‐SA nanocomposite hydrogels with various concentration of PVA solution were investigated using image pro Plus software, as shown in Figure (a’,b’,c’). For the sample of 2%PVA/3%GO‐SA, the diameter of micropores distributed in the range of 0–1.8 μm, especially concentrating in the range of 0–0.6 μm . For the samples of 4%PVA/3%GO‐SA and 5%PVA/3%GO‐SA, the diameter of macropores distributed both in the range of 0–4.5 μm, while the diameter of micropores focused in the range of 0.15–0.2 μm and 0.05–0.2 μm, respectively, indicating that with increasing concentration of PVA solution, the pore diameter distribution became wider, but the average pore diameter decreased.…”

“…For the sample of 2%PVA/3%GO-SA, the diameter of micropores distributed in the range of 0-1.8 μm, especially concentrating in the range of 0-0.6 μm. 29 For the samples of 4% The permeability of PVA/GO-SA nanocomposite hydrogel beads prepared at different concentration of PVA solution was depicted in Figure 7. It could be seen that the visible light transmission of ink solution at band 400-700 nm decreased with increasing concentration of PVA solution, indicating that the dense network structure formed at high concentration of PVA solution, resulted in the decrease of the permeability of PVA/GO-SA nanocomposite hydrogel.…”

Surface sedimentation and adherence of Nano‐SiO2 to improve thermal stability and flame resistance of melamine‐formaldehyde foam via sol‐gel method

“…Melamine‐formaldehyde foam (MF) is prepared through the emulsion and foaming of melamine‐formaldehyde resin . This kind of thermalset foam has a high open‐cell ratio over 90% and three‐dimensional network connected by melamine‐formaldehyde resin fibers with length‐diameter ratio of 10 to 20.…”

“…Melamine-formaldehyde foam (MF) is prepared through the emulsion and foaming of melamine-formaldehyde resin. [1][2][3][4][5] This kind of thermalset foam has a high open-cell ratio over 90% and threedimensional network connected by melamine-formaldehyde resin fibers with length-diameter ratio of 10 to 20. This foam possesses many advantages such as excellent sound absorption, high adsorption to various solvents, and efficient thermal insulation property.…”

Preparation and characteristics of Aziridine-Benzoguanamine-Urea-Melanmine-Formaldehyde resins

“…However, the high degree of crosslinking density in cured MF resin makes it inherently brittle, which resulted in limiting its application. Thus, the modification of melamine resin (MF) has become a research hotspot [1][2][3][4][5][6][7].…”