Study of the Influence of Stabilizers on the Properties of Carbamide for-Maldehyde Binder and Fc Plywood

Abstract

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

Kinetics of quartz sand and its mixtures drying by microwave radiation

“…Gypsum and cement solidification, for ex ample, realizes as result of their mixing water influence, which is one of hydration reactions components and participates in certain form new crystalline hydrates formation [14]. Phos phate binders solidify according to coagulation -polycon densation mechanism [15], thermosetting resins -according to polycondensation mechanism [16], etc. At the same time, SSS could be solidified by polycondensation mechanism with new solid astringent chemical compounds formation in it or by coagulation mechanism as dehydration result (as dehydration result or certain organic compounds using), its pH value de creasing, silicate modulus increasing, etc.…”