https://doi.org/10.29013/AJT-23-7.8-21-24
Tillayeva Dildora, Teacher in general and inorganic chemistry of Faculty of Natural Sciences, Bukhara state university
Sharipov Muzafar, Ph. D. in technical sciences, professor of the Department of General and inorganic Chemistry, the Faculty of Natural Science, Bukhara state university
Panoyev Nodir,
Ph. D. in technical sciences, Associate Professor of the Department of Chemistry Bukhara Engineering and Technology Institute,
INFLUENCE OF RHEOLOGICAL MODIFIERS ON THE PROPERTIES OF FILMS OF THE ADHESIVE COMPOSITIONS BASED ON OXIDIZED STARCH
Abstract. The article studied the hydrodynamic properties of adhesives based on oxidized starch with rheological modifiers. The development is aimed at solving the problems ofwet strength of glue joints based on them when used for surface gluing of corrugated boards.
Keywords: adhesive, oxidized starch, rheology, modifiers, wet strength, glue, corrugated board.
1. Introduction of many types of packaging papers and boards, such
Starch is one of the oldest and most common as board for flat layers, corrugated paper, and wrap-auxiliaries used in the manufacture of paper and ping paper, uses recycled paper as the main raw ma-
board. It is one of the main binding materials used in terial. This range requires the lowest cost per ton of
paper production,and, moreover, the cheapest com- product. In order to use waste paper in a wide range
pared to other binders [1]. The main use of starch of pulp and paper products, it must be subjected to
is to increase the strength of paper (especially sur- deep refining with a high degree of recovery of paper-
face strength). The use of modified starches gives an forming properties, which requires significant invest-
additional effect associated with an increase in the ments. Materials obtained from such raw materials retention of fine fibers, filler, optical bleaching, and do not have a sufficient level of strength, rigidity, and
sizing agents by them [2]. surface finish [4].
This effect is expressed in a decrease in the un- One of the significant disadvantages of cardboard
even properties of the paper on the sides of the is its weak wet strength. This significantly narrows the
sheet, which is especially important for those types scope of its application in cases where it is required
of products in which both sides are working, for ex- to maintain the strength of the package in conditions
ample, paper for writing and printing. The addition of high humidity. At the same time,a decrease in the
of starch to the mass reduces the dustiness of the pa- wet strength of cardboard also negatively affects
per, increases the retention of fillers, and improves its adhesive properties, which in turn increases the
and stabilizes the rosin sizing [3]. The production number of manufacturing defects [5].
With insufficient water-holding capacity of the adhesive, a rapid loss of the first portions of moisture occurs. With a lack of moisture, starch is simply not able to gelatinize and show its adhesive properties. The moment when the starch is able to gelatinize with the manifestation of adhesive properties stops when the moisture content in the starch suspension becomes less than 60%. If up to this point, the starch grains have not had time to gelatinize, then further they behave as an inert filler of the glue joint [6].
Therefore, it is important that the adhesive has increased water-retaining capacity at the initial stage, when starch gelatinization occurs, and quickly dries at the second stage after gluing, so as not to reduce the productivity of the equipment. This problemcan be reduced by developing new formulations of ad-hesives for the production of corrugated cardboard. Namely, by introducing water-retaining additives and additivesinto the composition of the adhesive, which would accelerate the drying of the adhesive at the stage of drying out of the adhesive joint [7]. So, referring to the properties and glue compositions of adhesive materials, we have developed other compositions based on corn starch oxidized by H.O. [8].
2. Practical part
The methods for preparing adhesives from oxidized starch (OS) granules may for convenience be classified under three main headings: 1) Heat treatment of OS gelatinized pastes with Na2SiO3 paste. 2) Polyacrylamide (PAA) treatment of the OS as paste; 3) Preparation of the adhesive based on OS formed by the addition of PAA and Na2SiO3. Various modifying agents such as PAA and Na2SiO3 were added to the adhesive of OS formed to ensure that a suitable working consistency was obtained and also to effectively prolong the shelf time of the adhesive composite formed.
The results of experimentalstudies have shown that when using various modifications of glue based on corn starch, the following patterns can be traced. First to obtain an adhesive of optimal composition, studies were carried out on homogeneity, medium, viscosity and humidity [9]. The humidity of adhesive films directly affects to wet strength of corrugated board. The resulting compositions by adding the components step by step gave a homogeneous adhesive composition with a yellowish tint. Forming of adhesives based on OS are shown in the (figure 1).
A
Figure 1. Glues based on OS with PAA
It is interesting that the resulting pastes have different attitudes to different solvents when obtaining their films. Five films formulations were prepared using the concentration of oxidized starch varied from 6 to 8 g and included sodium silicate in relation to the dry weight of starch from 0.1 to 0.3 g and polyacrylamide
B C
(A), with Na2SiO3 (B) with all of them (C)
from 1.2 to 1.8 g and distilled water to complete 100 g of solution. A two-component paste containing OK in each and silicate or PAA was prepared, followed by a variation of the mixture of the latter with OK in a three-component composition. The solvents used were ethyl acetate, dioxane, and propyl alcohol. Some
formulations did not give good films with, some with propanol. A mixture of OK-PAA with ethyl acetate did propanol and some with dioxane. For example, the not give an equal film thickness. Some of these good composition OK-silicate gives a very brittle film with films obtained with solvents are shown in (Figure 2).
ABC Figure 2. The films obtained from pastes OS with PAA in dioxane (a), with Na2SiO3 in ethyl acetate (B), and with all of them in propanol (C)
The shown film drawings show that adhesive of supramolecular formations, the strength of the
mixtures give good films in the indicated solvents, film and its elongation increase (table). But in the
but these mixtures did not give good films in other table given also the values of physical-mechanical
solvents. If we compare the strength characteristics properties of glues without OS were no in (Figure
of films, it turns out that with an increase in the size 1.2) also.
Table 1.- Physical-mechanical properties of films based on OS, PAA, and Na2SiO3
Contain solution (in mass.%) Tensile Strength, (MPa) Elongation of break (%) Contain solution (in mass.%) Tensile Strength, (MPa) Elongation of break (%)
OS (8) - Na2SiO3(0.l) 1.4 ± 0.1 7.2 ± 0.2 OS (6) - PAA (1.6) 4.3 ± 0.3 14.3 ± 0.8
PAA (1.8) 2.1 ± 0.2 8.1 ± 0.3 OS (7) - - Na2SiO3(0.2) - PAA(1.2) 5.5 ± 0.5 18.2 ± 0.9
Na SiO (0.3) - PAA(1.4) 3.2 ± 0.4 12.4 ± 0.6
The noted tendency of an increase in the tensile strength of the film with the introduction of PAA is apparently related to the acceleration of the process of formation of supramolecular formations during formation from the studied highly dispersed systems (rather large supramolecular formations already exist), which, in turn, causes an increase in the degree of crystallinity of the films. An increase in elongation at break indicates the influence of an additional factor inherent in systems containing additives of highly dispersed PAA. Obviously, the introduction of PAA
prevents the mutual ordering of the formed enlarged supramolecular formations.
As a result, under tension, the process of mutual ordering ofcrystallites makes a significant contribution to the magnitude ofdeformation, which can explain the increase in the elasticity offilms obtained from polymer compositions containing OS-PAA-Na2SiO3. It follows that when PAA is introduced into the composition, the elastic-viscous solid-like system transforms into an elastic-plastic system, which is one of the important requirements for the properties of adhesives.
References:
1. Ermakov S. G., Xakimov R. X. Technology of the paper. Perm: Permian state tech. university, 2002.
2. Wang X. H., Jiang C. In Encyclopedia of Surface and Colloid Science; Somasundaran, P., ed; CRC Press Taylor and Francis Group, Ciudad, 2006.
3. Jaycock M.J., Phillipson M. D., Zetter C., Vihervaara T. International Patent. WO1998024972A1. WIPO (PCT). (11.06.1998).
4. Mishurina O. A., Chuprova L. V., Mulina E. R., Ershova O. V. Properties of cardboard bushings. J. Modern problems of science and education.- Vol. 1. 2014.- P. 254-255.
5. Fischer S. A. Structure and wet strength activity of PAE resins having azetidinium functionality. J. Tappi 79. 1996.- P. 179-185.
6. Preparation ofadhesives [Electronic resource]: Building-Domik / 2010.- Access mode: URL: http://stro-im-domik.ru/sbooks/book/5/art
7. Adhesives for packaging purposes [Electronic resource]: Publishing House "Real-Press"/2004.- Access mode: http://www.real-press.com/article.php?aid=238
8. Tillaeva D. M., Sharipov M. S., Kurbanov K. K. Study of the hydrolytic stability of oxidized starch gels in adhesive compositions with polyacrylamide and sodium silicate // Electron Journal of Universum, 2022. - No. 4(94).
9. Tillaeva D. M., Sharipov M. S. "Study of the compatibility of components of adhesive polymer compositions intended for the production of corrugated cardboard" // - Tashkent. Journal of Composite materials, - Vol. 2. 2023. - P. 22-25.