In premises with a massive stay of people according to the standards, materials with reduced combustibility should be used. Cellulose containing materials are fire hazardous. The article presents the results of a study of indicators of materials with combustion retardants for rooms with people staying – textile fabrics, chipboards. The effect of flame retardant additives on the weight loss of samples of wood boards under fire exposure was studied. The influence of the type and duration of impregnation to reduce the combustibility and drying temperature of the impregnated textile materials on the time of their flame burning is investigated.
Volumes of plywood production with increased water resistance for indoor and outdoor use (FSF brand) are increasing in Russia. The demand for it in the country and in the world continues to grow. The phenol-formaldehyde oligomer during the curing process passes through the stages of resol, resitol and resite. Ensuring long-term water resistance of plywood is possible only if the resite stage is reached and the solidified phenol-formaldehyde resin (FFR) reaches non-melting and insoluble state. The problem is that the industrial process of FSF plywood pressing is carried out in the rezitol temperature range. In literature, there are conflicting data on the temperature ranges of the stages of the FSF polycondensation process. The authors have proposed to operate with scientific data on the temperature ranges of FFR curing, confirmed by the results of spectroscopic studies. It is necessary to develop phenol-formaldehyde binder compositions capable of curing to the resite stage at lower pressing temperatures than unmodified FSF to ensure the necessary operational characteristics of FSF plywood. In this study, a number of modifiers have been proposed that potentially reduce the time it takes to press plywood at low temperatures. The gelatinization time of the phenol-formaldehyde binder based on the SFZh-3014 resin (according to 20907-2016 State Standard) and modifying additives (hydrogen peroxide, eight-water zinc sulfate, ammonium alum, anhydrous magnesium chloride, six-water iron chloride, six-water aluminum chloride, aluminum dimethyl sulfate, dimethyl glyoximate, and sulfate, sulfosalicylic two-water acid) have been determined. A study of the gelatinization process in the presence of a large number of modifying additives (more than 1.5%) revealed a significant deterioration in the spreadability of the binder. Therefore, it is recommended to use FFR curing accelerators in the amount not exceeding 1-1.5%.
One of the urgent tasks is the development of new thermal insulation materials to improve the energy efficiency of construction. In this work, new composites were obtained based on previously unused cellulose-containing waste. The theoretical and experimental substantiation of the possibility of increasing the water resistance of the heat-insulating composite has scientific significance. The features of the supramolecular structure of cellulose are analyzed. As a result of studies of the process of structure formation of a new heat-insulating material, it has been established that to ensure stable heat-insulating properties of composites from cellulose-containing waste, it is advisable to use a phenol-formaldehyde binder, water glass, or alumochromophosphate. The developed composite has a swelling 2.7 ... 3 times less, and water absorption 2.2 ... 2.4 times less than mineral wool slabs. The coefficient of thermal conductivity of the new composite material, depending on the type of cellulose-containing filler, ranges from 0.076 to 0.092 W/m∙K, which makes it possible to recommend it for use in thermal protection of buildings.
The problem of stabilizing the properties of the urea-formaldehyde binder during storage is relevant for both glued products and resins. Changing the performance of the resin during storage makes it difficult to apply a binder and leads to a deterioration in the physical and mechanical properties of plywood. The effect of glycerol, mono- and triethanolamine, as well as a mixture of glycerol and monoethanolamine on the nominal viscosity of the resin after 56 days of storage, has been studied. The use of glycerol and monoethanolamine (including in the complex) reduces the nominal viscosity of the resin by 13.5-24.8%. The use of triethanolamine as a stabilizer makes it possible to reduce the nominal viscosity by 35% in comparison with the index of an unstabilized oligomer. Mechanical properties of FC plywood based on the stabilized and unstabilized binder has been studied. It was found that glycerol additive (or glycerol in combination with monoethanolamine) significantly reduces strength characteristics of plywood, which makes it irrational to use these stabilizers. The addition of 0.2% triethanolamine to CFS allows a 35% reduction in the nominal viscosity of the resin, while the cohesive strength of the binder decreases by 1.5%. The result is within the framework of the dispersion of the indicator, i.e. strength reduction is negligible. The static bending strength of plywood with a stabilized triethanolamine binder is more important than that of control specimens without the addition of stabilizers. The results of the study enable to recommend the addition of triethanolamine in an amount of 0.2% by weight of urea-formaldehyde resin as a rational stabilizer
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