RESEARCH ON THE DEPENDENCE OF THE TYPE OF FILLER ON THE ELECTROSTATIC CHARGE GENERATED DURING THE FRICTION OF COTTON RAW MATERIAL AND POLYMER COMPOSITE COATING

ABSTRACT

The results of the process of the formation of electrostatic charge as a result of the friction of cotton raw material with the coating are presented. It was found that the addition of graphite as a filler minimizes the generation of electrostatic charges in the friction of cotton raw materials and polymer composite coatings.

АННОТАЦИЯ

Представлены результаты процесса образования электростатического заряда в результате трения хлопкового сырья с покрытием. Установлено, что добавка графита в качестве наполнителя минимизирует образование электростатического заряда при трении между хлопковым сырьем и полимерными композиционными покрытиями.

Keywords: electrostatic charge, polymer composite coating, filler, graphite, pneumatic transport, dielectric material, anti-static coating.

Ключевые слова: электростатический заряд, полимерно-композитное покрытие, наполнитель, графит, пневмотранспорт, диэлектрический материал, антистатическое покрытие.

As the demand for cotton and its products increases in the world, it becomes important to preserve the natural properties of cotton fiber and seed using modern techniques and technologies in the cotton ginning industry.

Operational reliability of cotton pretreatment technological equipment can be achieved through the targeted use of high-performance composite materials. By using polymer composite materials on the surfaces of technological equipment, it is possible to reduce the level of mechanical damage to cotton fiber and seeds.

It has been noted that there are a number of specific shortcomings in the technological equipment of cotton preliminary processing [1].

•  injury of cotton fiber and seed;
•  emergence of noise and fire hazard;
•  high friction coefficient;
•  increased risk of fire as a result of collision of foreign hard rocks in the cotton with working parts of the machine;

The use of polymer composite materials in the main working parts of cotton pretreatment machines and mechanisms helps to eliminate or minimize a number of the above disadvantages.

But as a result of using polymer composite coatings on the surfaces of machines and mechanisms, polymer composite coatings generate more charges than metals. The extent to which these charges pose a fire hazard has not been studied.

  It is known that the main reason for the appearance of static electricity is the physical process that occurs when two different types of materials come into contact (Fig. 1). That is, when two materials interact with each other, freely moving electrons settle in the material. Due to the fact that the material itself does not have an electrically conductive property, electrons remain on the surface of the dielectric material and accumulate as charges [2].

Figure 1. Pairs in the formation of electric charge

The formation and accumulation of static electric charges on the surfaces of pneumotransport, which is one of the technological processes of preliminary processing of cotton, is considered very dangerous. Especially when it occurs around flammable materials, it creates a fire hazard due to the flash that occurs when the static charges accumulated on the surface of the material are affected by another material or the charges on it. For this reason, when working with dielectric materials, it is necessary to take into account the static charges accumulated in them and pay great attention to ways to eliminate them.

As we know, cotton is a very flammable material. Therefore, even a single flash can cause the entire product in the enterprise to burn. Since polymer composite coatings are a dielectric material, static electric charges appear when it is exposed to cotton current [3]. It is natural that electric charges are generated due to the friction of metal pneumatic transport equipment and cotton used today, but since metal is a good conductor of electric current, it ensures that electric charges do not accumulate on the surfaces. Polymer-based composite coatings are dielectric materials, so electrostatic charges accumulate in them. In this case, when one of the two materials is constantly affected, that is, when the flow of cotton continuously passes through the pipe, the electrons in the cotton begin to accumulate along the surface of the polymer composite coatings. But after a certain time, the surface of the coating is saturated with static charges and instead of receiving electrons, it begins to give them to cotton. For this reason, in our scientific research work, it is important to study the dependence of the type, quantity and physical properties of fillers on ensuring that the static charges formed as a result of the friction of cotton raw material with the surface of polymer composite coatings pass without accumulating on the surface surfaces factors [4].

So, the technological process of preliminary processing of cotton depends on the formation of static charge in the interaction of cotton with polymer composite coatings on the surfaces of pneumotransport pipes;

•  humidity of cotton;
•  to the actual contact surface of the polymer composite coating with cotton;
•  physical properties of the covering material;
•  chemical composition of polymer composite coating;

From the above, we can see that the formation of the main electric charge depends more on the composition of the polymer composite coating, the components that make it up, that is, it also depends on the amount and type of fillers, which are one of the main constituents of the coating. identification is one of the priority tasks [5].

The dependence of the amount of fillers in polymer composite coatings on electric charges was determined using the "Electrofeldmeter EFM 022" device (Fig. 2). It is possible to determine the electrostatic charges on the surfaces of various materials, their location, polar areas of their surfaces, and the size of the electrostatic charge.

Figure 2. Electrofield meter EFM 022

ES0202/1G megohmmeter device was used to determine the specific electrical resistance of the material, which is one of the factors affecting the formation of electrostatic charge in polymer composite coatings (Fig. 3). The megohmmeter is used to determine the electrical conductivity properties of electrical and dielectric materials. Their main advantage is that they do not need to be connected to a current source, they are equipped with a high-voltage generator and allow testing samples with high accuracy [6].

Figure 3. ES0202/1G megohmmeter

Table 1.

Lists the ingredients for obtaining an anti-static coating during the rubbing process of polymer composite coatings with cotton raw materials.

1 table tracks for anti-static coating

Based on the above compositions, graphite was first added as a filler to the samples with 5 different compositions, and then talc filler was added instead of graphite to the polymer composite coatings with the same composition [7]. Below is the surface charge density of samples made of talc and graphite added as a filler.

Figure 4. Graph of change of surface charge density depending on the type and quantity of PK coating fillers.

As we know, graphite is practically pure carbon and has high thermal and electrical conductivity. Therefore, it is possible to increase thermal and electrical conductivity by adding graphite to the PK material. As can be seen from the graph above, the surface charge density decreases with the increase in the amount of graphite, which means that when the PK coating is in contact with cotton raw materials, the amount of electric charge begins to be released less [8].

Talc is considered to be an environmentally friendly dispersible filler, and by adding it to the PK material, it improves water resistance, heat resistance and electrical insulation properties of the material. As can be seen from the graph above, adding talc as a filler to the composition of PCM has been found to increase the dielectric properties of the material.

Conclusion

Thus, depending on the type, amount and properties of the fillers that make up the PCM, the law of formation of electric charge was studied in the interaction with cotton raw material and PK coating. According to this, it was determined that the least electric charge is created by adding graphite among various fillers. It was found that the mechanical properties of the material decrease with an increase in the amount of filler in the composition of PCM.

References:

1. Джумабаев А.Б. Трение и повреждаемость хлопка. – Ташкент: «Стандарт», -2011, - 276 с.
2. AF Diaz, RM Felix-Navarro. A semi-quantitative tribo-electric series for polymeric materials Journal of Electrostatics, 62 (2004), pp. 277–290
3. McCarty, Logan S., et al. “Ionic Electrets: Electrostatic Charging of Surfaces by transferring Mobile Ions upon Contact.” Journal of the American Chemical Society (2007). Web. 5 May 2014.
4. Джумабаев А.Б., Зиямухамедова У.А., Убайдуллаев С.К. Совершенствование стандартизированных методов определения риботехнических свойств материалов с хлопком и повышение эффективности их использования при управлении качеством продукта // STANDART. – Ташкент, 2008. –№1. – С. 14-15.
5. Зиямухамедова У.А., Хабибуллаев А.Х., Джумабаев Д.А. Свойства гетерокомпозитных полимерных покрытий для применения в хлопкоочистительных технологических оборудованиях, получаемых активационно-гелиотехнологическим методом // STANDART. –Ташкент, 2009. – № 3. – С.37-39.
6. Nozimbek A. et al. Improvement of Physical and Mechanical Properties of Plastic Parts Used in Machine Building //Universum: технические науки. – 2021. – №. 3-4 (84). – С. 52-55.
7. Turgunaliyev E., Abidjanovich D. M. Standard safety test results of Chevrolet tracker //СОВРЕМЕННАЯ НАУКА: АКТУАЛЬНЫЕ ВОПРОСЫ, ДОСТИЖЕНИЯ И. – 2019. – С. 57.
8. Elbek T., Fazliddin B., Durbek V. DEVELOPMENT OF METHODS FOR DETECTING AND PREVENTING FAULTS IN THE BRAKING SYSTEM OF CARS //Universum: технические науки. – 2021. – №. 12-7 (93). – С. 32-35.