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Section 7. Chemistry
https://doi.org/10.29013/AJT-20-7.8-37-41
Eshmurodov Khurshid Esanberdievich, Termez State University, Termez E-mail: khurshid.eshmurodov.86@mail.ru
Turaev X.,
Termez State University, Termez, Tashkent
Djalilov A., Tashkent Research Institute of Chemical Technology, Tashkent
Geldiev Yu.,
Termez State University, Termez, Tashkent
Babamuratov B., Termez State University, Termez, Tashkent
DEVELOPMENT OF CARBAMIDE-FORMALDEGIDE SMOLA-BASED GLUE COMPOSITIONS MODIFIED WITH SILICON ORGANIC COMPOUNDS
Abstract. In this study, modified adhesive compositions based on urea-formaldehyde resin with siliconorganic compounds were developed. Composite plates are made on the basis of the obtained glue and crushed reeds. The effect of the modifier on the physical and mechanical properties of the plates was studied.
Keywords: urea-formaldehyde resin (UFR), tetraethoxysilane (TES), liquid glass, cane, reed plate.
Introduction wood-chipboard. It is determined by the Resolution
Today, as the demand for wood products around of the President of the Republic of Uzbekistan dated the world increases, so does the demand for its al- February 20, 2019 No PP-4198 "On measures to radi-ternative types. In particular, the furniture and con- cally improve and comprehensively develop the construction industries cannot be imagined without struction materials industry", ie by 2021 to increase wood and its alternative types. Reforestation, which the production of chipboard (DSP) - 380 thousand is declining year by year, will take hundreds of years, cubic meters 8 of the summary indicators of promisa great deal of labor and expense. Preserving them is ing projects in the construction materials industry in very important from an environmental point of view. 2019-2021 in Annex 3 to the Resolution of the Gov-
In our country, great attention is paid to the con- ernment ofthe Republic of Uzbekistan dated May 23,
struction industry, in particular, the production of 2019 No. PQ-4335 "On additional measures for the
accelerated development of the construction materials industry" -clause - "Project for the organization of production of wood-chipboard (DSP) from cotton stalks, reeds, straw, and other plant stalks" and the Cabinet of Ministers of the Republic of Uzbekistan dated April 11, 2019 No. 297 "Further development of production of wood-chipboard and their alternatives" On additional measures to - It is planned to increase the production of chipboard based on local alternative wood raw materials.
Research work is underway to develop an innovative technology for the production of formaldehyde-free wood-chip boards from cotton stalks, reeds, straw and other plant stems on the basis of local raw materials. In the production of wood-chip boards were studied the processes of extraction of local raw materials - cotton stalks, reeds, straw and other plant stalks, separation into large and small fractions, mixing with glue and bonding. Inexpensive, environmentally friendly and environmentally friendly ingredients based on local raw materials were selected for the preparation of the glue.
Phenol-formaldehyde (PFR) and urea-formaldehyde resins (UFR) are widely used products. They are widely used in the production of wood shavings, mineral fiber boards and similar building materials, despite a number of disadvantages such as high toxicity ofvapors, flammability, hydrophilicity, short-term storage of resin. The cheapness of formaldehyde and the lack of a substitute have led to an increase in usage over the last half century [1-2].
Alternative types of wood, such as wood chipboard, wood fiberboard, medium-density wood fiberboard - MDF (MDF-Medium Density Fibre-board), laminated medium-density wood fiberboard - LMDF, etc. are mainly used in the production of phenol-formaldehyde or urea - formaldehyde resins are used. These resins release formaldehyde, which does not react during production and when used as an adhesive, and is formed as a result of partial decomposition. In particular, when the amount of formaldehyde in the air is 0,5 mg / m3, it is known
to cause serious damage to the eyes, nose, respiratory system, causing skin diseases [3-5].
In the study, plates were prepared on the basis of glue modified urea-formaldehyde resin with alkaline solutions of silicates, organic monomers, organo-silicon compounds. Their physical and mechanical properties were studied. In this case, the silicon-organic part is consumed in small quantities. The main mass of the glue is urea-formaldehyde resin. When new resins are used, there is almost no need to change the existing technology [6-9].
Research methods and tools
In the experiment, formalin, urea, sodium silicate (liquid glass), tetraethoxysilane (TEOS), methyl methacrylate, acrylic acid, tetrafurfurylsylan, poly-acrylamide, n-toluene sulfoxic acid; thermopress, viscometer, "fire tube" method was used.
Experimental part
It has been performed the follow the experiment, 205 g of 36,9% (pH = 3.6) formalin and 8.4 g of 26.9% ammonia solution were added to a 500 ml four mouth flask and mixed for 10 min. While stirring, 120 g of urea was added and stirred for another 20 min until the urea was completely dissolved (pH = 9.1). After the mixture was heated for another 1.5 h at 80-90 °C, a 5 g aqueous solution of sodium silicate with a density of 1,474 g/cm3 and a modulus of silicate of 1,08 was added (pH = 8,2). The reaction mixture was cooled to a temperature of 70 °C while stirring. 18 g of modifier and another 24 g of urea were then added to the reactor and the mixture was kept at 60-65 °C for 40 min. It was then cooled to a temperature of 30 °C.
The modifier is in an aqueous dispersed state and contains 10% methyl methacrylate, 7.2% acrylic acid, 12% tetraethoxylane, 4% tetrafurfurylsylane and 6.8% polyacrylamide. The viscosity of the finished modifier (pH = 8.0) is 48 s when measured on a viscometer VZ-246 with a diameter of 4 mm [10].
A plate measuring 100x100 mm was prepared and tested on the basis of the obtained glue and crushed reeds of 10/2 fraction. 0.1% n-toluene sulfoxic acid
relative to the glue mass was used as a hardener in the preparation of the plate. The plate was prepared in a thermopress for 8 minutes at a pressure of 2 MPa, at 180 °C. The thickness of the prepared slab is 16 mm, the density is 850 kg/m3.
Physical and mechanical properties of the obtained slab were determined in accordance with GOST 10634-78, GOST 10635-78, GOST 1063678. Flammability was determined on the basis of the
Table 1.- Basic technological
mass loss in combustion by the method of "Flame Pipe", as a percentage of water absorption and permeability thickness [11-12].
To determine the strength of the samples, their resistance to perpendicular stress was tested after soaking in cold water for 24 h. Outcome analysis
The results of the study of the main technological properties of the modified glue are given in (table 1).
properties of modified glue
Percentage of modifier,% The surface tension of the glue, mN/m Wetting angle, grad. Viscosity according to ВЗ-246 with a nozzle diameter of 4 mm, с pH Gelatinization time, 150 °C, с
0 66 68 74 7.93 60
1 57 64 77 7.59 57
2 55 61 80 7.48 53
3 53 58 85 7.39 50
4 52 55 91 7.31 47
5 51 54 98 7.25 45
6 50 55 105 7.20 44
As can be seen from Table 1, the technological The physical and mechanical properties of the properties of the removable adhesive vary depending plates obtained on the basis of modified glue are on the amount of modifier. given in (table 2).
Table 2.- Physical and mechanical properties of the obtained plates
Percentage of modifier in glue composition,% Static crush resistance, MPa Resistance to perpendicular stress, MPa Swelling in thick-ness,% Bulk swell,% Water absorption,%.
0 10.5 0.22 32.6 32.49 78.6
1 12.3 0.29 28.2 26.42 72.4
2 13.5 0.34 25.3 25.63 64.7
3 15.1 0.39 22.0 24.88 58.3
4 16.8 0.43 19.9 23.56 52.8
5 18.0 0.48 16.7 22.91 49.0
6 18.5 0.50 16.1 21.96 48.1
As can be seen from (table 2), its physical and Figure 1. shows the dependence of the mass loss mechanical properties are optimal when the amount (%) of the obtained slab samples on the amount of of modifier is 5% of the glue mass. modifier in the "Fire Pipe" for 3 minutes.
Figure 1. Dependence of the mass loss (%) on the amount of modifier in the "Flame tube" for 3 minutes of the obtained slab samples
Figure 2. shows the dependence of the time taken for the 30% mass loss in the "fire pipe" on the amount of modifier.
As can be seen from (figure 1), the combustion mass loss of the plate has the lowest value (12%) when the modifier content is 5%. When the amount of modifier is higher than this, the mass loss rate in combustion is almost unchanged.
From (figure 2) it can be seen that it took 15 minutes for 30% mass loss when the modifier amount was 5%. There was no significant difference when the modifier content was 6%. It was proved that the optimal amount of the modifier is 5%.
Conclusion
The results show that the new type of glue modified with sodium silicate and silicon-organic compounds in many respects does not lag behind phenol-formaldehyde and urea-formaldehyde res-
Figure 2. Dependence of the time spent on 30% mass loss in the "fire pipe" on the amount of modifier
ins. Wood panels based on it are resistant to fire and moisture, and their strength is not inferior to other similar types of boards.
The amount of modifier based on the obtained silicon-organic compound was found to have a significant effect on the strength of the product. As the amount of modifier increases, water resistance and durability increase. It was found that 5% modifier was the most acceptable amount relative to the total mass of glue, and that the strength and water resistance of the resulting product changed very little when the percentage was higher.
Based on the results ofthe study, it can be said that the use of modified adhesives based on organosilicon compounds for the production of environmentally safe wood shavings will lead to a major change in the industry. This will reduce the use of toxic substances in the production of wood chipboard.
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