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Rubber blends based on styrene–butadiene rubber, ethylene–propylene–diene monomer rubber and a combination of both rubbers were cured with different sulfur and peroxide curing systems. In sulfur curing systems, two type of accelerators, namely tetramethylthiuram disulfide, N-cyclohexyl-2-benzothiazole sulfenamide, and combinations of both accelerators were used. In peroxide curing systems, dicumyl peroxide, and a combination of dicumyl peroxide with zinc diacrylate or zinc dimethacrylate, respectively, were applied. The work was aimed at investigating the effect of curing systems composition as well as the type of rubber or rubber combinations on the curing process, cross-link density and physical–mechanical properties of vulcanizates. The dynamic mechanical properties of the selected vulcanizates were examined too. The results revealed a correlation between the cross-link density and physical–mechanical properties. Similarly, there was a certain correlation between the cross-linking degree and glass transition temperature. The tensile strength of vulcanizates based on rubber combinations was higher when compared to that based on pure rubbers, which points out the fact that in rubber combinations, not only are the features of both elastomers combined, but improvement in the tensile characteristics can also be achieved. When compared to vulcanizates cured with dicumyl peroxide, materials cured with a sulfur system exhibited higher tensile strength. With the application of co-agents in peroxide vulcanization, the tensile strength overcame the tensile behavior of sulfur-cured vulcanizates. [ABSTRACT FROM AUTHOR]

Manganese‐zinc ferrite, nickel‐zinc ferrite, and the combinations of both ferrites in constant level 200 phr were incorporated into acrylonitrile‐butadiene rubber. The amount of carbon black was constant in each composite −25 phr. The second series of composites was fabricated with similar composition, but the total content of ferrites or ferrites combinations was 300 phr, while the content of carbon black was 25 phr. The work was focused on investigation of electromagnetic absorption shielding effectiveness of composites and their physical‐mechanical properties. During the study, good correlation between conductivity, permittivity, and electromagnetic absorption parameters was established. Higher conductivity was reflected in higher permittivity of composites, which subsequently resulted in their lower absorption shielding performance. The experimental outputs revealed that absorption shielding effectiveness was enhanced with increasing with proportion of nickel‐zinc ferrite, which pointed out to higher absorption shielding potential of nickel‐zinc ferrite. The physical‐mechanical properties were found not to be influenced by the type of ferrite or ferrites combinations. The higher overall content of ferrites in rubber matrix caused the decrease in tensile characteristics of composites, suggesting that ferrites are inactive fillers considering the physical‐mechanical properties. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]