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The goal of the present work was to study the preparation and properties of rubber magnetic composites and investigation of strontium ferrite activity in examined materials. Three types of rubber matrices, namely butadiene rubber as non-polar elastomeric matrix, nitrile butadiene rubber (NBR) and NBR/poly(vinyl chloride) blend as polar elastomeric matrices, were compounded with strontium ferrite and other additives in order to prepare rubber magnetic composites. Ferrite dosage was given in modified and unmodified forms in concentration scale ranging from 0 to 100 phr. The influence of magnetic filler content on the mechanical properties of composites was investigated. Correlation between Wolf activity coefficient and Payne effect in relation to the mechanical properties of tested systems was discussed. The results revealed that the observed characteristics are dependent on the type of rubber matrix and also on the type of ferrite. [ABSTRACT FROM PUBLISHER]

Abstract: Elastomeric magnetic composites are materials with ferromagnetic fillers as one of the constituents and rubber blend as polymer matrix. Ferrites, as commonly used magnetic fillers, might be able to influence the long-term stability of rubber materials, mainly if they are applied in high concentrations. Therefore, the thermo-oxidative and ozone stability of ferrite as well as ferrite and carbon black filled composites based on natural and butadiene rubber were studied by oven ageing and thermogravimetric analysis. The results revealed that ferrite alone also ferrite in combinations with carbon black influences the properties of evaluated materials in various ways. But the thermo-oxidative stability of prepared composites seems not to be influenced by the amount of ferrite even in case of high magnetic filler contents. From thermogravimetric curves it became evident that the thermal degradation of prepared materials also was not influenced by the doping content of ferrite. The ozone ageing tests demonstrated that the influence of ferrite on the ozone stability of natural rubber as well as butadiene rubber based composites was ambiguous. In case of natural rubber based composites filled with combinations of ferrite and carbon black, it can be stated that the more carbon black rubber materials contain, the better is the resistance against ozone degradation. [Copyright &y& Elsevier]

The focus of the work was to prepare elastomeric magnetic composites based on a highly elastic polymer matrix (1,4-cis butadiene rubber). Three modifi cations of the same type of strontium ferrite SrFe12O19, type FD8/24 were applied as magnetic fi llers. The applied ferrites differed in particle size distribution and other structural and magnetic characteristics. The work is focused on the preparation of rubber compounds for making elastomeric magnetic composites and evaluation of magnetic fi llers infl uence on curing characteristics, physical-mechanical and magnetic properties of prepared composites. The study is also dedicated to the cross-link density of vulcanizates. [ABSTRACT FROM AUTHOR]

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]

Three types of composites were tested for electromagnetic interference (EMI) absorption shielding effectiveness, the curing process, and their physical–mechanical properties. For the first type of composites, nickel–zinc ferrite, manganese–zinc ferrite, and both fillers in their mutual combinations were incorporated into acrylonitrile–butadiene rubber. The overall content of the filler, or fillers, was kept at 200 phr. Then, carbon black or carbon fibers were incorporated into each rubber formulation at a constant loading of—25 phr, while the content of magnetic fillers was unchanged, at —200 phr. This work focused on the understanding of correlations between the electromagnetic shielding parameters and electrical conductivity of composites in relation to their EMI absorption shielding effectiveness. The absorption shielding abilities of materials were evaluated within a frequency bandwidth from 1 MHz to 6 GHz. This study revealed good correlation among permittivity, conductivity, and EMI absorption effectiveness. Although the absorption shielding efficiency of composites filled only with ferrites seems to be the highest, the absorption maxima of those composites reached over 6 GHz. The application of carbon-based fillers resulted in the higher electrical conductivity and higher permittivity of composites, which was reflected in their lower absorption shielding performance. However, the composites filled with ferrites and carbon-based fillers absorbed electromagnetic radiation within the desired frequency range. The presence of carbon-based fillers caused improvement in the tensile behavior of composites. This study also demonstrated that the higher the ratio of nickel–zinc ferrite in combined magnetic fillers, the better the absorption shielding efficiency. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The study was focused on the investigation of trans-polyoctylene (TOR) influence on cross-linking as well as mechanical and rheological properties of rubber compounds based on styrene-butadiene rubber (SBR). SBR was compounded with different proportions of TOR in the concentration range from 0 to 30 phr. Integration of TOR into rubber leads to the prolongation of the optimum curing time and scorch time and thus the decrease of the curing rate. Higher content of TOR led to less viscous rubber due to the plasticizing effect. Cross-link density of vulcanizates was reduced, which correlates with higher elongation at break. Tensile strength and hardness of vulcanizates increased with the increasing TOR content, probably due to the increasing amount of the crystalline phase. [ABSTRACT FROM AUTHOR]

The sulfur curing system, peroxide curing system and their combinations were applied for the cross-linking of unfilled and carbon black-filled rubber formulations based on ethylene-propylenediene-monomer rubber. The results demonstrated that the type of curing system influenced the course and shape of curing isotherms. This resulted in the change of curing kinetics of rubber compounds. The cross-link density of materials cured with combined vulcanization systems was lower than that for vulcanizates cured with the peroxide or sulfur system. Good correlation between the cross-link density as well as the structure of the formed cross-links and physical–mechanical characteristics of the cured materials was established. Both filled and unfilled vulcanizates cured with combined vulcanization systems exhibited a higher tensile strength and elongation at break when compared to their equivalents vulcanized in the presence of the peroxide or sulfur curing system. It can be stated that by proper combination of vulcanization systems, it is possible to modify the tensile behavior of vulcanizates in a targeted manner. On the other side, dynamical–mechanical properties were found not be significantly influenced by the curing system composition. [ABSTRACT FROM AUTHOR]

Rubber magnetic composites were prepared by incorporation of strontium ferrite in concentration scale ranging from 0 phr to 100 phr into rubber matrices based on natural rubber (NR) and acrylonitrile-butadiene rubber (NBR). The composite systems were exposed to the conditions of thermooxidative aging at 70°C for 7, 14, and 28 days. The influence of aging period on the behavior of prepared materials was considered based on investigation of their cross-link density, physical–mechanical, and magnetic characteristics. The results revealed that the influence of thermooxidative aging on composite characteristics is dependent on the type of rubber matrix. The thermooxidative aging was found to have negative effect on the cross-link density and tensile properties of composites based on NR, which were deteriorated in dependence of aging time. The possible influence of magnetic filler content on aging mechanism was observed during last period of aging after which the decrease in cross-link density and tensile characteristics was more pronounced with increasing content of strontium ferrite. By contrast, the cross-link density, modulus, and hardness of composites based on NBR were found to be positively influenced by aging as their values showed increasing trend with extension of aging period. [ABSTRACT FROM AUTHOR]

In this work, magnetic soft ferrites, namely manganese–zinc ferrite, nickel–zinc ferrite and combinations of both fillers, were incorporated into acrylonitrile-butadiene rubber to fabricate composite materials. The total content of ferrites was kept constant—300 phr. The second series of composites was fabricated with a similar composition. Moreover, carbon fibres were incorporated into rubber compounds in constant amount—25 phr. The work was focused on investigation of the fillers on absorption shieling performance of the composites, which was investigated within the frequency range 1–6 GHz. Then, the physical–mechanical properties of the composites were evaluated. The achieved results demonstrated that the absorption shielding efficiency of both composite types increased with increasing proportion of nickel–zinc ferrite, which suggests that nickel–zinc ferrite demonstrated better absorption shielding potential. Higher electrical conductivity and higher permittivity of composites filled with carbon fibres and ferrites resulted in their lower absorption shielding performance. Simultaneously, they absorbed electromagnetic radiation at lower frequencies. On the other hand, carbon fibres reinforced the rubber matrix, and subsequent improvement in physical–mechanical properties was recorded. [ABSTRACT FROM AUTHOR]

The work deals with the application of biopolymer fillers in rubber formulations. Calcium lignosulfonate was incorporated into styrene–butadiene rubber and acrylonitrile–butadiene rubber in a constant amount of 30 phr. Glycerol in a concentration scale ranging from 5 to 20 phr was used as a plasticizer for rubber formulations. For the cross-linking of the compounds, a sulfur-based curing system was used. The study was focused on the investigation of glycerol in the curing process; the viscosity of rubber compounds; and the cross-link density, morphology, physical–mechanical, and dynamic mechanical properties of vulcanizates. The study revealed that the application of glycerol as a plasticizer resulted in a reduction in the rubber compounds' viscosity and contributed to the better dispersion and distribution of the filler within the rubber matrices. The mutual adhesion and compatibility between the filler and the rubber matrices were improved, which resulted in the significant enhancement of tensile characteristics. The main output of the work is the knowledge that the improvement of the physical–mechanical properties of biopolymer-filled vulcanizates can be easily obtained via the simple addition of a very cheap and environmentally friendly plasticizer into rubber compounds during their processing without additional treatments or procedures. The enhancement of the physical–mechanical properties of rubber compounds filled with biopolymers might contribute to the broadening of their potential applications. Moreover, the price of the final rubber articles could be reduced, and more pronounced ecological aspects could also be emphasized. [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]

Calcium lignosulfonate in the amount 30 phr was incorporated into rubber compounds based on pure NBR and an NBR carbon black batch, in which the content of carbon black was 25 phr. Glycerine, as a cheap and environmentally friendly plasticizer, was applied into both types of rubber formulations in a concentration scale ranging from 5 to 20 phr. For the cross-linking of rubber compounds, a sulfur-based curing system was used. The work was aimed at the investigation of glycerine content on the curing process and rheological properties of rubber compounds, cross-link density, morphology and physical–mechanical properties of vulcanizates. The results show that glycerine influences the shapes of curing isotherms and results in a significant decrease between the maximum and minimum torque. This points to the strong plasticizing effect of glycerine on rubber compounds, which was also confirmed from rheological measurements. The application of glycerine resulted in better homogeneity of the rubber compounds and in the better dispersion and distribution of lignosulfonate within the rubber matrix, which was subsequently reflected in the significant improvement of tensile characteristics of vulcanizates. A higher cross-link density as well as better physical–mechanical properties were exhibited by the vulcanizates based on the carbon black batch due to the presence of a reinforcing filler. [ABSTRACT FROM AUTHOR]

In this work, dicumyl peroxide (DCP), di-tert-butyl peroxide (DTBP), di(tert-butylperoxyisopropyl)benzene (DTBPIB), and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (DDTBPH) were used for cross-linking of rubber matrix based on Ethylene-propylene-diene monomer rubber (EPDM). The aim was to investigate the influence of curing temperature and the type and content of peroxide on curing process of rubber compounds, cross-link density, and physical-mechanical properties of vulcanizates. The results revealed that higher curing temperatures promote faster decomposition of organic peroxides, leading to the faster reactions of peroxide radicals with rubber chains. The increase in temperature resulted also in the increase of cross-linking degree. Although, side reactions as chain scission take over the main cross-linking reactions at very high temperatures resulting in the decrease of cross-link density. The increasing content of peroxides resulted in the acceleration of curing reactions and to increase of cross-link density. The fastest curing kinetics exhibited rubber compounds cured with DCP. However, vulcanizates cured with DCP were found to have the lowest cross-link density. In generally, the dependences of modulus, hardness, and elongation at break of vulcanizates were in line with the dependences of the cross-link densities, while higher tensile strength were found to have vulcanizates cured at higher temperatures and lower peroxides content. [ABSTRACT FROM AUTHOR]

Calcium lignosulfonate in different loadings was applied to the rubber matrix based on EPDM. A sulfur curing system, organic peroxide, and a combination of organic peroxide with two coagent types were used for cross-linking of rubber compounds. The work was focused on the investigation of filler content and curing system composition in the curing process, cross-link density, morphology, and physical–mechanical properties of composites. The achieved results demonstrated that the curing parameters of rubber compounds cured with the sulfur system were significantly different from those cured with peroxide systems. There was also an observed different influence of curing systems composition on cross link density, though in all cases, the degree of cross-linking showed a decreasing trend with increasing content of lignosulfonate. The tensile strength of the composites cured with sulfur system and organic peroxide was comparable, regardless of lignosulfonate loading. This points to the application of both curing systems in cross-linking of rubber compounds with biopolymer filler. However, the introduction of coagents in peroxide vulcanization led to the improvement of adhesion and compatibility between the rubber and the filler on the filler–rubber interface. This subsequently resulted in the improvement of the tensile characteristics of composites. The introduction of organic peroxide in combination with coagent seems to be a very simple and efficient way for the preparation of biopolymer-filled composites with applicable physical–mechanical properties. [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]

Elastomeric magnetic composites were prepared by incorporation of strontium ferrite into polymer matrices based on natural as well as butadiene rubber. Besides the rubber and ferrite, or the combinations of ferrite and carbon black (in case of natural rubber), the model rubber compounds contained only ingredients which support curing process. The study was dedicated to the observation of fillers dispersion degree in the rubber matrices and investigation of physical-mechanical and magnetic properties of prepared composites. The results indicate that the dispersion degree of ferrite in the rubber matrices is not very high, but it can be positively influenced by the addition of carbon black. Despite of the fact that ferrite exhibits only low reinforcing effect on cross-linked elastomeric materials, physical-mechanical properties can be also positively influenced by the mutual change in combinations of both fillers (ferrite and carbon black). The prepared materials seem to have suitable magnetic and elastic properties. [ABSTRACT FROM AUTHOR]

The lignosulfonates are water‐soluble anionic polymers, which are considered as byproducts from the production of wood pulp using sulfite pulping. Calcium lignosulfonate is chosen as a filler according to previous research due to its effect on the properties of the blends. It is added in the concentration range from 10 to 60 phr to the blends with NBR, SBR, and EPDM. It is found out that the increasing concentration of filler has a favorable effect on the values of physical—mechanical properties of vulcanizates. [ABSTRACT FROM AUTHOR]

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. [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]

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. [ABSTRACT FROM AUTHOR]

In the first part of the research, rubber magnetic composites were prepared by incorporation of strontium and barium ferrite in concentration scale ranging from 0 to 200 phr into rubber matrices based on acrylonitrile–butadiene rubber and styrene–butadiene rubber. The main objective was to investigate the influence of the type and content of magnetic filler on the cross-link density, physical–mechanical and magnetic characteristics of the prepared composites. In the second part of the study, the content of magnetic fillers was kept on constant level—200 phr and the main aim was to investigate the change in mutual combination of both fillers on the cross-linking and properties of the rubber magnets. The results revealed that both fillers show reinforcement effect in the rubber matrices. The higher tensile strength of composites was achieved by application of barium ferrite. Magnetic properties of composite materials were significantly influenced by magnetic characteristics of magnetic fillers. Higher remanent magnetic induction of barium ferrite was reflected in higher remanent magnetization of the equivalent composites. On the other hand, higher coercivity of strontium ferrite resulted in higher coercivity of strontium ferrite-filled composites. [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]

Two types of composites based on natural rubber (NR) and strontium ferrite were tested in this study. Composites of the first type were prepared by incorporation of strontium ferrite in the concentration range ranging from 0 to 100 phr (parts per hundred rubber) into pure NR based rubber matrix, while with those of the second type, strontium ferrite was dosed in the same concentration level into NR based rubber batch with constant amount of carbon black — 25 phr. For rubber matrices cross-linking, a standard sulfur based curing system was used. This work is focused on the effect of magnetic filler content on physico-mechanical, magnetic and thermo-physical properties of composite materials. Subsequently, the cross-link density and the structure of the formed sulfidic cross-links were examined. The results showed that the cross-link density of both types of composites increased with the increasing content of magnetic filler, while the structure of the sulfidic cross-links was almost not influenced by the amount of strontium ferrite. Tensile strength of rubber composites with pure rubber matrix was slightly improved by the incorporation of ferrite, while in case of composites based on a carbon black batch, the incorporation of magnetic filler resulted in the decrease of this characteristic. The presence of magnetic filler in both types of composites leads to a significant increase of the remanent magnetic induction. [ABSTRACT FROM AUTHOR]

Rubber magnetic composites were prepared by incorporation of barium ferrite in constant amount—50 phr into acrylonitrile-butadiene rubber. Dicumyl peroxide as the curing agent was used for cross-linking of rubber magnets alone, or in combination with four different types of co-agents. The main aim was to examine the influence of curing system composition on magnetic and physical-mechanical properties of composites. The cross-link density and the structure of the formed cross-links were investigated too. The results demonstrated that the type and amount of the co-agent had significant influence on cross-link density, which was reflected in typical change of physical-mechanical properties. The tensile strength increased with increasing amount of co-agents, which can be attributed to the improvement of adhesion and compatibility on the interphase filler-rubber due to the presence of co-agents. Magnetic characteristics were found not to be influenced by the curing system composition. The application of peroxide curing systems consisting of organic peroxide and co-agents leads to the preparation of rubber magnets with not only good magnetic properties but also with improved physical-mechanical properties, which could broaden the sphere of their application uses. [ABSTRACT FROM AUTHOR]

Strontium ferrite was incorporated into different rubber matrices to prepare rubber magnetic composites. Three types of elastomers, butadiene rubber BR as non-polar elastomer, acrylonitrile butadiene rubber NBR and blend acrylonitrile butadiene rubber-polyvinyl chloride NBR/PVC as polar elastomers were chosen as rubber matrices. Surface modified strontium ferrite as magnetic filler was applied in concentration scale ranging from 0 to 100 phr. Besides the rubber and the filler, the rubber compounds contained only the ingredients of sulfur curing system. The results revealed that thermo-physical and magnetic properties of composites increased with doping content of ferrite. Moreover, the improvement of mechanical properties in dependence on strontium ferrite content was also recorded. It can be stated that the improvement of composite properties is in close correlation with the increase of polarity of the rubber matrix. POLYM. COMPOS., 38:2480-2487, 2017. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

In the present work, rubber magnetic composites were prepared by incorporation of strontium ferrite into rubber matrices based on natural rubber (NR) and acrylonitrile butadiene rubber (NBR). The sulfur and peroxide curing systems were introduced in cross-linking of rubber matrices. The research was aimed at the evaluation of magnetic filler content and type of curing system on the cross-link density, physical–mechanical and magnetic properties of prepared composites. The relationship between the composition of elastomers and cross-link structure within the rubber matrices, formed by applying different curing systems, was under investigation through strain–stress behavior of tested materials. The achieved results showed that ferrite behaves as a reinforcing filler in peroxide-cured composites based on NR, and in both, sulfur as well as peroxide-cured composites based on NBR. The results also demonstrated that the cross-linking degree and the type of cross-link structure as well as the composition of rubber matrices, to a large extent, influence the property spectrum of tested composite systems. [ABSTRACT FROM AUTHOR]

In the present work, rubber magnetic composites were prepared by incorporation of strontium ferrite into rubber matrices based on natural rubber (NR) and acrylonitrile-butadiene rubber (NBR). Sulphur, peroxide and mixed sulphur/peroxide curing systems were introduced in cross-linking of rubber matrices. The aim was to investigate the influence of curing system composition on physical-mechanical, thermo-physical and magnetic properties of prepared rubber composites and the curing process. Then, the determination of cross-link density and the structure of cross-links were under consideration. The achieved results showed that all investigated parameters were changed depending on the composition of curing system, but also on the type of rubber matrix. While the tensile strength of composites based on NR increased with increasing amount of sulphur in mixed curing systems, in case of composites based on NBR, the highest value of tensile strength reached the value of the sample cured with equivalent ratio of sulphur and peroxide. On the other hand, thermo-physical and magnetic characteristics were found not to be dependent on the curing system composition. The results revealed that not only the composition of curing system, but also the type of rubber matrix plays an important role when preparing the final materials. [ABSTRACT FROM AUTHOR]

This work deals with the preparation and properties evaluation of magnetic composites with acrylonitrile butadiene rubber matrix, which are able to shield electromagnetic radiation. In addition to the rubber matrix, these materials contained soft magnetic filler (Li or H40) and ingredients necessary for vulcanization process of prepared rubber compounds (sulfur, accelerator N-cyclohexyl-2-benzothiazole sulfenamide, activators ZnO, and stearin). This study was aimed at the preparation of elastomeric composite materials and evaluation of the influence of ferrite weight fraction on curing characteristics, physical-mechanical, and magnetic properties. The results showed that with increasing content of filler, the moduli, and tensile strength decline. Conversely, elongation at break increased with increasing amount of filler. All composites containing 200 and more phr of ferrite showed sufficient absorption shielding properties, whereas lithium ferrite shows better shielding properties compared with manganese-zinc ferrite H40. POLYM. COMPOS., 37:2933-2939, 2016. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Rubber magnetic composites were prepared by incorporation of unmodified and surface modified strontium ferrite into rubber matrices based on NBR and NBR/PVC. Strontium ferrite was dosed to the rubber matrices in concentration scale ranging from 0 to 100 phr. The main goal was to investigate the influence of the type of ferrite on the curing process, physical-mechanical and magnetic properties of composites. The mutual interactions between the filler and rubber matrices were investigated by determination of cross-link density and SEM analysis. The incorporation of magnetic fillers leads to the increase of cross-link density and remanent magnetic induction of composites. Moreover, the improvement of physical-mechanical properties was achieved in dependence on the content of magnetic fillers. Surface modification of ferrite contributed to the enhancement of adhesion on the interphase filler-rubber. It can be stated that ferrite exhibits reinforcing effect in the composite materials and this reinforcing behavior was emphasized with the increase in polarity of the rubber matrix. [ABSTRACT FROM AUTHOR]

Rubber magnetic composites were prepared by incorporation of strontium ferrite into natural rubber-based continuous matrix. The prepared rubber compounds have model character and besides the rubber and the filler, they contained only ingredients of peroxide curing system, dicumyl peroxide as curing agent, and ethylene glycol dimethacrylate as co-agent. The work was focused on the evaluation of curing system composition and magnetic filler content on curing process, cross-link density, physical–mechanical and magnetic properties of tested materials. The achieved results revealed that the evaluated properties are dependent on the composition of curing system and on the content of ferrite too. Ferrite incorporated in the rubber matrix imparts magnetic properties to the composites considerably. In addition, the improvement of physical–mechanical properties with doping content of ferrite was observed. [ABSTRACT FROM AUTHOR]

Rubber magnetic composites were prepared by incorporation of strontium ferrites in natural rubber-based elastomer matrix. The work was aimed at the evaluation of magnetic filler influence on physical-mechanical, magnetic and thermal properties of prepared composites. The study was also dedicated to the investigation of microstructure and evaluation of interactions between strontium ferrites and natural rubber. The observed parameters are dependent on the type of ferrite and on the content of applied ferrite, too. Surface modification of ferrite leads to the improvement of interfacial conditions and adhesion between the rubber matrix and the magnetic filler. [ABSTRACT FROM AUTHOR]

Thanks to their good magnetic properties, NiZn ferrites can be used as the soft magnetic filler in magneto–polymer composites. The ferrites having general composition NixZn1-xFe2O4 (x=0.30, 0.33, 0.36, 0.42, and 0.50) were prepared by means of ceramic method and the magnetic properties, such as initial permeability \mui and Curie temperature TC were investigated. The sample with composition Ni0.33Zn0.67Fe2O4 having \mui=1316 and TC=95\ ^{\circ}C was chosen as the filler for magneto–polymer composites. The aim of the work was the study of preparation and properties of magnetic polymer composites based on natural rubber SMR 20 in a wide range of concentrations (0–600 phr). The influence of ferrite content on magnetic, physical–mechanical and rheological properties of prepared composites was investigated. The effect of the concentration of ferrite filler on the complex permeability \mu=\mu^\prime-j\mu^\prime\prime of the composites in the frequency range from 10 MHz to 3 GHz as well as the physical–mechanical and rheological properties is evident. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In the present work, composite materials were prepared by incorporation of manganese-zinc ferrite, carbon black and combination of ferrite and carbon black into acrylonitrile-butadiene rubber (NBR). For cross-linking of composites, standard sulfur-based curing system was applied. The main goal was to investigate the influence of the fillers on the physical-mechanical properties of composites. Then, the electromagnetic absorption shielding ability was investigated in the frequency range 1 MHz–3 GHz. The results revealed that composites filled with ferrite provide sufficient absorption shielding performance in the tested frequency range. On the other hand, ferrite behaves as an inactive filler and deteriorates the physical-mechanical characteristics of composites. Carbon black reinforces the rubber matrix and contributes to the improvement of physical-mechanical properties. However, composites filled with carbon black are not able to absorb electromagnetic radiation in the given frequency range. Finally, the combination of carbon black and ferrite resulted in the modification of both physical-mechanical characteristics and absorption shielding ability of hybrid composites. [ABSTRACT FROM AUTHOR]

Strontium ferrite was compounded with acrylonitrile butadiene rubber to prepare rubber magnetic composites. For cross-linking of the prepared materials, peroxide curing systems consisting of dicumyl peroxide as curing agent and zinc salts of acrylic and methacrylic acids as co-agents were used. The amount of strontium ferrite was kept constant in all experiments, while the main objective of the work was to investigate the composition of curing system and both types of co-agents on the cross-linking, physical-mechanical, dynamic and magnetic properties of the rubber magnets. The results showed that the change in composition of curing system has significant influence on cross-link density and properties of the tested composite materials. With an increasing amount of zinc based co-agents, significant improvement of tensile strength was achieved. The application of zinc based co-agents in peroxide vulcanization of rubber magnetic composites leads to the preparation of rubber magnets with not only good magnetic properties, but also with improved physical-mechanical characteristics. [ABSTRACT FROM AUTHOR]