Highly flame retardant melamine-formaldehyde cross-linked cellulose nanofibrils/sodium montmorillonite aerogels with improved mechanical properties

A facile cross-linking strategy to construct flame retardant cellulose nanofibril (CNF)/sodium montmorillonite (MMT) aerogels with improved mechanical properties, by incorporating melamine-formaldehyde (MF) resins into precursor suspensions followed by a freeze-drying process, is reported in this work. Scanning electron microscopy images indicate that MF cross-linking does not significantly change the microstructures of CNF and CNF/MMT aerogels. However, the cross-linking improves the materials’ mechanical and flame properties. By incorporating 50 wt% of MF, the compression moduli and compressive stress of CNF aerogels increase by 316% and 114%, respectively. The limiting oxygen index (LOI) value of CNF aerogels also increases from 17.1% to 23.4%. Further addition of MMT increases the CNF aerogels’ LOI value to 57% and increases the maximum decomposition temperature by nearly 20 °C. This occurs because MMT and MF induce a synergistic effect which improves the flame retardant properties of the CNFs aerogels. In CNF/MMT composite aerogels, the introduction of 34 wt% of MF leads to a 54.6% reduction of the peak of heat release rate and a 53.2% decrease in total heat release. CNF aerogels made from sustainable feedstocks with excellent mechanical properties and high flame retardancy, like those discussed herein, show promise as fire resistant biofoamsPostprint (author's final draft

Cellulosic films obtained from the treatment of sugarcane bagasse fibers with N -methylmorpholine- N -oxide (NMMO)

Ethanol/water organosolv pulping was used to obtain sugarcane bagasse pulp that was bleached with sodium chlorite. This bleached pulp was used to obtain cellulosic films that were further evaluated by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). A good film formation was observed when temperature of 74 °C and baths of distilled water were used, which after FTIR, TGA, and SEM analysis indicated no significant difference between the reaction times. The results showed this to be an interesting and promising process, combining the prerequisites for a more efficient utilization of agro-industrial residues.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), (CNPq), and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Brazil; Fundação para a Ciência e a Tecnologia (FCT) and CEMU

Impregnation of Bombax ceiba and Bombax insigne wood with a N-methylol melamine compound

Methylated N-methylol melamine (NMM) is known for its ability to enhance physico-mechanical properties, anti-fungal ability, and hydrophobicity and was therefore used to impregnate two less used and non-durable wood species from Myanmar, Bombax ceiba and Bombax insigne. Solution uptake, weight percent gain and nitrogen content were increased by increasing melamine concentrations with B. ceiba always achieving higher values compared with B. insigne. According to the leaching results, a higher degree of condensation after curing as well as a better crosslinking of NMM could be obtained at higher temperatures. However, both curing temperatures used (90 and 120 A degrees C) resulted in almost the same amount of nitrogen fixed in the cell wall. UV microspectrophotometry confirmed the penetration of the NMM into different morphological regions of wood tissues, which was again supported by the analysis of point measurement spectra of treated and untreated specimens

Fragility behavior of melamine formaldehyde three dimensional network

International audienc

Thermodynamically “strong” and kinetically “fragile” polymeric glass exemplified by melamine formaldehyde resins

International audienc