INFLUENCE OF MINERAL AND ORGANIC FILLERS IN QUANTITATIVE RATIO ON RUBBER PROPERTIES

ABSTRACT

Fillers are among the essential components in rubber compounding, significantly influencing the technological and operational properties of rubber while reducing production costs. This study examines the effect of mineral and organic fillers in various quantitative ratios on the composition and performance of rubber materials. Mineral fillers—such as calcium carbonate, talc, kaolin, graphite, and wollastonite—were introduced into rubber mixtures and analyzed through thermal calcination at 500°C. Organic filler (technical carbon) obtained from the devulcanization process was also investigated at different loadings and calcined at 800–950°C to determine its reinforcing capability. The results demonstrate that mineral fillers increase the volume and residue content of rubber but provide limited reinforcement, whereas technical carbon significantly enhances mechanical properties due to its large specific surface area and structural activity. The optimal amount of organic filler was determined to be 30 parts by mass, closely matching the properties of raw rubber. These findings can be applied for optimizing rubber formulations in the production of tires, plastics, paints, adhesives, and conductive materials.

АННОТАЦИЯ

Наполнители являются одними из важнейших компонентов резиновых смесей, существенно влияя на технологические и эксплуатационные свойства резины, одновременно снижая производственные затраты. В данной работе изучается влияние минеральных и органических наполнителей в различных количественных соотношениях на состав и эксплуатационные свойства резиновых материалов. Минеральные наполнители, такие как карбонат кальция, тальк, каолин, графит и волластонит, вводились в резиновые смеси и анализировались путем термической прокалки при 500 °C. Органический наполнитель (технический углерод), полученный в процессе девулканизации, также исследовался при различных нагрузках и прокаливался при 800–950 °C для определения его армирующей способности. Результаты показывают, что минеральные наполнители увеличивают объем и содержание остатков резины, но обеспечивают ограниченное армирование, в то время как технический углерод значительно улучшает механические свойства благодаря своей большой удельной поверхности и структурной активности. Оптимальное количество органического наполнителя было определено равным 30 мас.ч., что близко к свойствам сырой резины. Полученные результаты могут быть применены для оптимизации рецептур резины при производстве шин, пластмасс, красок, клеев и проводящих материалов.

Keywords: raw material, rubber, carbon, pile of old tires, devulcanization, element, compound, activator, rubber, destruction, powder, waste, incineration, process, production, plastic, paint, ingredient, sulfur, mineral, organic, elastic, composition, resin, composition, ebonite, stabilization.

Ключевые слова: сырье, резина, углерод, утилизированые шины, девулканизация, элемент, соединение, активатор, резина, разрушение, порошок, отходы, сжигание, процесс, производство, пластик, краска, ингредиент, сера, минерал, органический, эластичный, состав, смола, композиция, эбонит, стабилизация

Introduction. Rubber is an elastic material obtained by vulcanizing natural or synthetic rubber - mixing with a vulcanizing agent (usually sulfur or organic peroxides) and then heating [1, p.584].

According to the degree of vulcanization, rubber is divided into soft (1-3% sulfur), medium-hard, and hard (more than 30% sulfur; ebonite).

The history of rubber technology highlights its evolving applications, including its early use in erasers and waterproof fabrics developed by Charles Macintosh.

Modern rubber formulations contain numerous components—accelerators, activators, plasticizers, anti-aging agents, dyes, special-purpose additives, and fillers. Fillers play a central role in determining the mechanical, technological, and functional properties of rubber products. Mineral fillers are inorganic substances of natural or synthetic origin, whereas organic fillers contain carbon-based compounds and are characterized by higher reinforcing potential.

Materials and methods. Rubber mixtures were prepared by introducing mineral fillers (calcium carbonate, talc, kaolin, graphite, and wollastonite) in varying proportions. Samples were thermally treated at 500°C for 1 hour in a muffle furnace to determine mineral residue content [5, p.98].

Mineral Filler Analysis

A total of seven samples were examined. The table below summarizes the mass before and after calcination:

Table 1.

The mass before and after calcination

Mineral fillers are inorganic dispersed substances of various chemical composition. Mineral fillers are divided into natural (chalk, talc, gypsum, kaolin, etc.) and synthetic (titanium, magnesium, zinc oxide, calcium and aluminum silicates, calcium fluoride, etc.) [2, p.258].

Organic Filler (Technical Carbon) Analysis

Technical carbon samples obtained during devulcanization were calcined at 800–950°C to determine their ash content. The results demonstrated that a loading of 30 parts by mass shows the most optimal reinforcement compared to other concentrations.

Result and discussion. After heating the rubber sample pieces in a muffle furnace at 500˚C for 1 hour, the samples were cooled and weighed on a calcined scale, and the mineral content of the 7 different rubber pieces calcined in the furnace was calculated in %.

The devulcanization process in Sample 1 and Sample 7 used more mineral salts. When heated in a muffle furnace at 500˚C for 1hour, residual mineral salts deposits remained in the crucible, as can be seen in the diagrams.

Figure 1. Results

When modifying rubbers as mineral fillers, the chemical composition of the filler determines the nature of the material, especially when the material is given functionality, the chemical composition of the filler plays a decisive role. In future experiments, it is appropriate to conduct studies of organic fillers, as well as to compare the effects and properties of mineral and organic fillers [3, p.170].

Another filler that improves the properties of rubber is organic fillers.

There are several grades of technic carbon used in industry: diffuse, furnace oil (PM and PGM) and thermal (TG-10). A specific type is selected depending on the composition to obtain a specific product. Technik carbon (Soot) is obtained in the process of cracking hydrocarbons at high temperatures, it undergoes purification and further processing.

Furnace Black one of the popular methods for producing carbon black. This procedure involves burning hydrocarbons at high temperatures in a reactor. The resulting product in the form of a fine powder is collected and purified before further use.

Channel Black This method is also known as lamp black; the procedure involves burning the product in a flame of fuel rich in hydrocarbons. The resulting raw material is also collected and processed by an appropriate method.

Carbon black is a form of elemental carbon, such a product is obtained because of the thermal decomposition of hydrocarbons. It consists of particles ground to a powder state, the size of which ranges from 10 to 500 nanometers or more. The quality of such products depends on the equipment and the features of the production process. For example, large surface area - due to which it can absorb other materials upon contact with them; durable color - the material is used as a black pigment; UV stabilization - to prevent them from fading in the sun; reinforcement - provides additional rigidity; conductivity - conducts electricity well [4, teh-impex.ru].

Experiments have shown that the organic filler in the rubber obtained during the devulcanization process can be calcined in a muffle at 800-950˚C, cooled and re-measured. The salt content X (%) is calculated by the following formula:

and its properties as an organic filler in rubber - technical carbon - were studied in quantitative ratios, and the comparison with the properties of mineral fillers is presented in the table below.

Table 2.

Conclusion. The study established those mineral fillers primarily increase volume and thermal residue but provide weak reinforcement. Organic filler (technical carbon) significantly improves mechanical and functional properties of rubber. The optimal amount of technical carbon was determined as 30 parts by mass, offering performance closest to raw rubber.

The findings are relevant for rubber, plastic, paint, adhesive, and electronic industries, where filler selection strongly influences final product performance.

Reference:

1. Rubber / Evstratov V. F. // Sample - Remensy. - Moscow: Soviet Encyclopedia, 1975. - PP. 584–586. - (Great Soviet Encyclopedia: [Vol. 30] / editor-in-chief Prokhorov A. Moscow; 1969–1978, Vol. 21).
2. Koshelev F. F., Kornev A. E., Bukanov A. M. ‘General Technology of Rubber’ Study Guide. Moscow. Chemistry 1978. – PP. 258-272.
3. Toshtemirova G.M., Muzaffarova X, A., Narmanova B.Yo. // Rezina tarkibining mineral qismlari tadqiqoti // ‘WOMEN IN STEM’ xalqaro forumi. Toshkent, 2025-yil, 12-13-fevral. Toshkent kimyo-texnalogiya institute. – PP.170. [in Uzbek]
4. [Electronic resource] URL: https://teh-impex.ru/
5. Muzafarova H.A., Mukhamedov G.V., Teshabayeva E.U.. Ikkilamchi rezinani depolymerlashning innovation technology, Yosh olimlar, master's degree va bakavariat talabalarini XXIX ilmiy-tekhnikaviy anzhumanining makolalar tuplami. ‘Umidli kimyogarlar -2020,’ Tashkent-2020. – PP. 98. [in Uzbek]