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Rubber compounds based on acrylonitrile‐butadiene rubber were filled with biopolymer fillers, namely kraft lignin, and calcium lignosulfonate. For cross‐linking of rubber compounds, sulfur curing system, dicumyl peroxide, and combination of dicumyl peroxide with trimethylolpropane trimethacrylate were used. The main objective of the work was to investigate the influence of biopolymer fillers content and curing system composition on vulcanization process of rubber compounds, cross‐link density, morphology, and physical‐mechanical properties of vulcanizates. The results revealed that rubber compounds filled with calcium lignosulfonate can be efficiently cured with sulfur as well as peroxide curing systems. Modulus, hardness, and elongation at break were strongly dependent on cross‐link density. Vulcanizates filled with high content of lignosulfonate exhibited comparable values of tensile strength, regardless of the curing system applied. The application of kraft lignin into peroxide systems cured rubber compounds resulted in undesirable reactions between functional groups of the biopolymer and peroxide radicals. Depletion of peroxide radicals resulted in significant deceleration of curing process and decrease in cross‐link density of vulcanizates. This was reflected in typical change of physical‐mechanical characteristics, decrease in modulus and hardness, and increase in elongation at break. Very good adhesion and compatibility between the kraft lignin and the rubber matrix resulted in enhancement of tensile behavior of vulcanizates cured with sulfur system. [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]

In the current study, manganese‐zinc ferrite in a concentration scale ranging from 100 to 500 phr was incorporated into acrylonitrile‐butadiene rubber having the constant amount of carbon black (20 phr) or carbon nanotubes (5 phr). The work was focused on the investigation of fillers combination on curing process, physical‐mechanical, and dynamic characteristics of composites. The electromagnetic interference absorption shielding efficiency of composites was subsequently investigated at low frequencies. The results revealed that composites filled with a combination of ferrite and CB are able to efficiently shield electromagnetic radiation in the tested frequency range 1 MHz to 3 GHz, while electromagnetic interference absorption shielding performance of CNT/ferrite composites was insufficient. The reason can be attributed to the outstanding increase of electrical conductivity of composites filled with combination of ferrite and CNT. As the best absorption shielding material can be considered the CB/ferrite composite containing 100 phr of ferrite, as it exhibited the widest absorption frequency bandwidth at return loss of −10 and −20 dB. The presence of ferrite in composites resulted in the decrease of cross‐link density, modification of curing characteristics and physical‐mechanical properties, and no significant influence on glass transition temperature. [ABSTRACT FROM AUTHOR]

In this work, sulfur vulcanization system, peroxide vulcanization system, and combined sulfur and peroxide curing systems are applied for cross‐linking of rubber compounds based on ethylene propylene diene monomer rubber. The goal is to investigate the influence of curing system composition on cross‐linking and properties of rubber formulations. The combination of both vulcanization systems in cross‐linking of rubbers combines the pattern of carbon–carbon linkages and sulfidic bridges, which gives the real presumption to modify physical–mechanical properties of final vulcanizates. The results reveal that the combination of vulcanization systems affects the curing characteristics, cross‐link density as well as physical–mechanical properties of tested materials. In comparison with vulcanizates cured only with sulfur or peroxide system, rubber compounds cross‐linked with mixed sulfur and peroxide curing systems exhibite higher tensile strength and elongation at break. [ABSTRACT FROM AUTHOR]

Strontium ferrite in constant loading is incorporated into acrylonitrile butadiene rubber in order to prepare rubber magnetic composites. Sulfur, peroxide and combined sulfur/peroxide curing systems are applied for cross‐linking of rubber composites. The work is focused on the investigation of curing system composition and thermo‐oxidative ageing on cross‐link density, physical‐mechanical and magnetic properties of rubber magnets. The results revealed that the cross‐link density and the structure of the formed cross‐links within the rubber matrices affect the property spectrum of vulcanizates. [ABSTRACT FROM AUTHOR]

Ethylene propylene diene monomer rubber was filled with multi‐walled carbon nanotubes to prepare composite materials with the effect of electromagnetic radiation (EMR) shielding. Sulfur‐based curing system as well as peroxide curing system were used for vulcanization of rubber compounds. The main goal of the work was the investigation of curing system composition and filler content on curing process, physical‐mechanical properties, cross‐link density, and shielding efficiency of the prepared composites. The results showed that curing characteristics and cross‐link density of composites were dependent on both, amount of carbon nanotubes and curing system composition. The incorporation of filler resulted in the enhancement of physical‐mechanical properties of composites. Higher values of tensile strength were found to have composites cured with organic peroxide in combination with co‐agent. The achieved results also demonstrated that carbon nanotubes filled rubber composites are suitable candidates for applications, in which shielding of EMR at low frequencies is based on reflection. [ABSTRACT FROM AUTHOR]

Rubber magnetic composites were prepared through the incorporation of magnetic soft lithium ferrite into acrylonitrile butadiene rubber. Standard sulfur‐based curing and peroxide curing systems were used for cross‐linking of rubber matrices. The experimental part was focused on the investigation of ferrite content and curing system composition on cross‐link density, physical‐mechanical, magnetic and shielding characteristics of composites. The results demonstrated that cross‐link density and physical‐mechanical properties of composites can be modified by both the amount of ferrite and composition of the curing system. The influence of curing systems on magnetic properties was negligible. It can be stated that the application of lithium ferrite to rubber matrix leads to the preparation of rubber composites with the ability to efficiently absorb harmful electromagnetic radiation in the tested frequency range. The shielding efficiency of composites increased with increasing content of magnetic filler. [ABSTRACT FROM AUTHOR]

Manganese‐zinc ferrite is incorporated into natural rubber in order to prepare rubber magnetic composites. The main goal of the work is to investigate the influence of content of magnetic soft ferrite on physical–mechanical and electromagnetic shielding properties of magnetic composites. The results reveal that the tested composites are able to efficiently shield the electromagnetic radiation by absorption mechanisms. All composites containing 200 phr or more filler exhibit sufficient absorption shielding. On the other hand, the strength characteristics of the composites decreases with increasing content of ferrite. [ABSTRACT FROM AUTHOR]

Manganese‐zinc ferrite as magnetic filler is compounded with NBR or NR based elastomer matrices in two steps. Manganese‐zinc ferrite is the most important part of elastomer compounds because of its magnetic properties, but it is inactive filler and thus carbon black is added into the rubber formulations as well. The rubber compound filled only with ferrite exhibits high viscosity and it is not able to be processed by extrusion. For this reason, rheological properties of all compounds with different ratio of processing additives and fillers are studied. It has been found out in our previous research that rubber compounds filled with 200 phr of ferrite showed the best electromagnetic shielding performance. Dispersion Z and dispersion D of cured and uncured elastomer compounds with processing additives Werbablend and Werbalub, which are mixed in laboratory and industrial kneading machine, are determined on an instrument disperGRADERTM αview. [ABSTRACT FROM AUTHOR]