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Manganese-zinc ferrite, nickel-zinc ferrite and the combination of both fillers were used for fabrication of composites. Then, carbon black was applied in combination with ferrites in the second type of composites. The main goal was to investigate the influence of fillers on absorption shielding efficiency and physical-mechanical properties of composites. It was revealed that incorporation of ferrites into rubber matrix leads to fabrication of composites that are able to absorb electromagnetic radiation. The higher was the amount of nickel-zinc ferrite in fillers combinations, the higher was the absorption shielding performance of composites. The results showed that nickel-zinc ferrite demonstrated better absorption shielding potential. The absorption shielding efficiency of composites filled with carbon black and ferrites was lower when compared to equivalent composites filled only with ferrites, which can be attributed to higher electrical conductivity of composites due to the presence of carbon black. On the other side, the incorporation of carbon black caused the improvement in physical-mechanical properties of composites, mainly the enhancement of the tensile strength, modulus and hardness.

Rubber magnetic composites were fabricated by incorporation of strontium ferrite in constant loading level in ethylene propylene diene monomer rubber and acrylonitrile butadiene rubber. Different curing additives based on peroxide, sulfur and combined sulfur/peroxide systems were introduced for cross-linking of rubber matrices. Both sulfur and peroxide curing systems lead to the formation of cross-links with different length and structure, which subsequently results in different properties of rubber products. Moreover, due to various bonding energies of the formed cross-links, rubber articles exhibit different propensity to degradation factors as to thermo-oxidative aging. Therefore, the work was aimed at the investigation of curing system composition and aging on cross-link density and properties of rubber magnetic composites. The achieved results point out to close correlation between cross-link density and physical-mechanical characteristics with exception of tensile strength, which showed increasing tendency with increasing amount of peroxide in combined vulcanization systems. It can be stated that no significant changes in physical-mechanical and magnetic properties were recorded during aging.

In this work, rubber composites were fabricated by incorporation of manganese-zinc ferrite alone and in combination with carbon-based fillers into acrylonitrile-butadiene rubber. Electromagnetic parameters and electromagnetic interference (EMI) absorption shielding effectiveness of composite materials were examined in the frequency range 1 MHz–3 GHz. The influence of ferrite and fillers combination on thermal characteristics and mechanical properties of composites was investigated as well. The results revealed that ferrite imparts absorption shielding efficiency to the composites in tested frequency range. The absorption shielding effectiveness and absorption maxima of ferrite filled composites shifted to lower frequencies with increasing content of magnetic filler. The combination of carbon black and ferrite also resulted in the fabrication of efficient EMI shields. However, the EMI absorption shielding effectiveness was lower, which can be ascribed to higher electrical conductivity and higher permittivity of those materials. The highest conductivity and permittivity of composites filled with combination of carbon nanotubes and ferrite was responsible for the lowest absorption shielding effectiveness within the examined frequency range. The results also demonstrated that combination of ferrite with carbon-based fillers resulted in the enhancement of thermal conductivity and improvement of mechanical properties. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

In the present work, barium ferrite in constant loading was dosed to the rubber matrices based on NR, SBR and NBR. Sulfur, peroxide and mixed sulfur and peroxide curing systems were applied for cross-linking of rubber magnetic composites. The application of sulfur or peroxide curing system leads to the formation of different types of linkages between rubber chain segments. As the structure of the formed cross-links plays a significant role in determining the final properties of rubber articles, the main aim of the work was to use the combination of curing systems in order to suppress the disadvantages of both systems and possibly to highlight their benefits. The results showed that composition of curing system has considerable influence on cross-link density of composites, which was subsequently reflected in typical change of physical-mechanical properties and glass transition temperature. The tensile strength was improved with increasing amount of peroxide curing system. The reason can be attributed to the presence of co-agent zinc methacrylate, which exhibits strong adhesion to magnetic filler and thus it contributes to the improvement of compatibility and homogeneity on the interphase filler–rubber. On the hand, there was observed no influence of curing system composition or type of rubber matrix on magnetic characteristics of composites. © The Author(s) 2020.

Rubber magnetic composites based on acrylonitrile butadiene rubber and strontium ferrite were cured with standard sulfur-based vulcanization systems as well as an organic peroxide. Zinc methacrylate (ZDMA) as a coagent was applied in both sulfur and peroxide vulcanization of rubber magnets. The aim was to evaluate the influence of ZDMA on curing characteristics and cross-link density of the prepared materials. Subsequently, physical-mechanical and magnetic properties were investigated. The results showed that ZDMA takes an active part in the cross-linking process of composites cured with an organic peroxide. Due to the presence of free radicals formed from peroxide decomposition, molecules of ZDMA polymerize into the nanostructures which can be physically adsorbed or chemically grafted onto rubber chains. Moreover, owing to zinc ions, ZDMA exhibits strong adhesion to ferrite filler and thus it contributes to the improvement of adhesion between the rubber and the filler on the interphase. The overall reinforcement of rubber magnetic composites was subsequently achieved. In the case of rubber magnets cured with the sulfur-based system, ZDMA acts as a conventional filler with a slight reinforcing effect due to the lack of free radicals required for its polymerization.

Styrene–butadiene rubber and acrylonitrile–butadiene rubber as elastomer matrices were filled with barium ferrite in order to prepare rubber magnetic composites. For cross-linking of rubber compounds, peroxide curing systems consisting of dicumyl peroxide as curing agent and four types of low molecular weight organic compounds as co-agents were used. The work was focused on the investigation of different types of co-agents on the cross-linking, physical-mechanical and magnetic properties of the prepared composites. The results revealed that the type and amount of co-agent has no influence on magnetic characteristics of composites. On the other hand, cross-link density and physical-mechanical properties were significantly dependent on the composition of curing system. Co-agents contribute to the improvement of adhesion on the interphase filler-rubber. Considering the type of rubber matrix, higher values of tensile strength exhibited composites based on acrylonitrile–butadiene rubber. As magnetic filler and co-agents are polar materials, their compatibility with polar elastomers like acrylonitrile-butadiene rubber is much higher when compared to no-polar elastomers like styrene–butadiene rubber. © 2019, Pleiades Publishing, Ltd.

Barium ferrite in constant amount (50 phr) was incorporated into styrene-butadiene rubber to prepare rubber magnetic composites. Dicumyl peroxide was used as a curing agent for cross-linking of the prepared composites. Four different types of low-molecular-weight organic compounds were applied as coagents to enhance the efficiency of cross-linking process and to improve the compatibility between the rubber and the filler on the interphase. The main goal of this work was to investigate the influence of the composition of peroxide curing system on cross-link density, physical–mechanical and magnetic properties of the composites. The results revealed that the type and amount of coagents have no influence on magnetic properties of the rubber magnets. On the other hand, cross-link density and physical–mechanical properties were significantly dependent on the composition of curing system. The increase of tensile strength can be attributed to the improvement of adhesion on the interphase filler–rubber due to the presence of coagents. © The Author(s) 2019.