КАРБАМИДОФОРМАЛЬДЕГИДНЫЕ СМОЛЫ, НАПОЛНЕННЫЕ ТЕХНИЧЕСКИМ ДИОКСИДОМ КРЕМНИЯ

The effect of silicon dioxide (SDO) on the physico-chemical properties of urea-formaldehyde resins and plywood made with the modified resins, has been studied. SDO addition to the resin increases its acidity and reactivity. This reduces the consumption of catalyst for resin curing 1,5−2,0 times, and plywood, obtained using SDO, has higher mechanical strength.Изучено влияние диоксида кремния (ДОК) на физико-химические свойства карбамидоформальдегидных смол (КФС) и фанеры, изготовленной с использованием наполненных смол. Добавка ДОК в смолу приводит к увеличе­нию ее кислотности и повышению реакционной способности. При этом снижается расход катализатора отверждения смолы в 1,5−2,0 раза, а фанера, полученная с использованием ДОК, имеет более высокую механическую прочность

Resource-saving technology of casting resins manufacture

Carbamidfuran and carbamiddianfuran pitches the technology of reception is developed for foundry manufacture resource-saving. As a source of formaldehyde and partially a carbamide it is used carbamidformaldehyd a concentrate. Concentrate use allows to receive pitch with the high maintenance of solids, to exclude a stage evaporation ready pitch, to reduce time of synthesis of pitch and to lower the expense of heat on its reception. The conducted tests of pre-production models of pitch in industrial conditions have shown its suitability for reception sand pitch mixes which apply to manufacturing casting from aluminium

Softwood kraft pulping with polyacrylonitrile fibers

This article presents data on the polyacrylonitrile (PAN) effect upon the elastoplastic and mechanical properties of kraft pulp (unbleached softwood sulphate pulp). In the present research the possibility of obtaining in vitro sulphate pulp together with reinforcing agent of polyacrylonitrile was studied. PAN consumption was varied from 0.05 to 0.20 wt % based on the dry weight of the chips. Micrographs of cellulose samples showed that PAN was distributed on the surface of cellulose fibers in the form of fine spherical shape particles and made it possible to increase the strength of kraft pulp by 15?18% (breaking length was increased from 8,480 up to 9,990 m, breaking strength ?from 93.8 up to 109.5 N, energy absorption at break ?from 76.0 up to 92.6 J/m 2 and folding endurance ?from 7 up to 13 double folds)

Fillers and catalysts effect on the physicochemical properties of urea-formaldehyde resins

In the present research the effect of different f illers on the composition of urea-formaldehyde resins (UFR) was studied. The usage of fillers in the composition of urea-formaldehyde resins makes it possible to reduce the resin consumption by 10–20%. Aluminum silicate type of fillers cannot be used conveniently in plywood technology because resin partic les initially agglomerate; then their swelling and hydration lead to the significant visc osity growth of the adhesive especially at a filler consumption rate more than 8% by weight of the resin. Sulfate and carbonate types of fillers can be used more preferable because in this case there are no agglomeration of resin particles and no quick solidification of adhesive composition. Viscosity of the adhesive composition decreases vice-versa with th e adding of silicate type filler into the urea-formaldehyde resin. Combining of different fillers types allows controlling the rheological properties of the adhesive composition. Compounds containing ions of three-valence meta ls are effective catalysts of urea-formaldehyde resins. The usage of such catalysts in plywood technology leads to condensation time reduction of urea-formaldehyde resins at 1.8–2.3 times which opens up additional possibilities for application of low-emission resins with a low formaldehyde content. Gelatination time of adhesive compositions prepared using the new effective catalysts for the condensation process of urea-formaldehyde resins remains for 2–4 hours

Investigation of the fiber composition effect upon sack paper properties

The article presents data on production volumes of sack paper, which is produced by the world's leading companies. The main raw material for the manufacture of this product is unbleached softwood sulphate pulp having a high cost. In the present research work the fiber composition effect upon sack paper properties was investigated. This makes it possible to determine the optimal mass ratio of unbleached kraft primary fibers (kraft pulp) and seco ndary fibers (waste paper) for the manufacture of sack paper. Doptimal continuous design (Kono, 1962) for the estimating second order polynomial full models was used as the experiment design for the optimization of the pulp fiber composition. Considering the restrictions on the quality parameters speci fied in GOST 2228–81 “Sack paper. Specifications” the analysis of the obtained experimental data using the search function in Mi crosoft Excel 2007 gave the following results on the sack paper fiber composition: kraft pulp content ( X1) – 43.30% of a. d. s.; polyacrylonitrile fibers content ( X2) – 0.15% of a. d. s.; waste paper content – 56.55% of a. d. s. During the experiment it was found that an increase of polyacrylonitrile fibers content from 0.05 to 0.20% in the kraft pulp structure leads to the increase of sack paper tensile strength by 25–28% (breaking length increased from 5,700 to 7,300 m). But paper whiteness at the same time decreased by 9.7%. This made possible to reduce the content of expensive kraft pulp in the composition of sack paper by 27% (taking into account the 30,000 t/year production of sack pa per, saving of kraft pulp can reach 8,000 t/year)

Rapid method for determining the composition of crude alcohol using diagrams composition – property

The preparation of a raw alcohol in a beer still is a periodic process which is accompanied by a flood, the reflux-to-product ratio and speed of sampling changes, unexpected temperature jumps etc. As the result, at formal conformity with the sampling temperature, the main product is polluted by fusel oils. The degree of pollution by fusel oils is above the requirements needed for further treatment which in turn requires an ad-ditional rectification. For this reason the process of periodic rectification needs continuous express control. The rapid method of the determination of the com position of crude alcohol using diagrams composition-properties was developed. There fractive index, the density and su rface tension were chosen as the physical properties characterizing the mixture. The re fractive index was measured on a digital portable refractometer PAL-RI made by the company ATAGO (Japan), the density was measured using a pick-nometer, the surface tension was measured at stallagometеr with a falling drop method. Experimental plan was realized on a simplex la ttice. The third-degree polynomial was used as a model. All calculations were made using the “Simplex” program. The adequate mathematical models (diagrams) were made which allowed us to determine the composition of crude alcohol using only three physical con-stants: density, refractive index, surface tension. Validity check of the model has shown that the error of the results does not exceed 3% rel. (ethanol concen tration) and 7% rel. (fusel oil concentration)