Search

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]

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 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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

Four types of peroxides in combination with two types of co-agents were used as cross-linking agents for the preparation of rubber compounds based on natural rubber. The effects of Type I and Type II co-agents on cross-linking and physical-mechanical properties of vulcanizates were investigated. The correlation between mechanisms of the interaction of co-agents with the rubber matrix in relation to the characteristics of tested systems was discussed. The results showed that the Type I co-agent influenced the rate and the state of cure. Physical-mechanical properties were improved by addition of the Type I co-agent. By contrast, the Type II co-agent had no contribution to the rate and state of cure. Moreover, physical-mechanical properties of vulcanizates deteriorated in the presence of this type of co-agent. [ABSTRACT FROM AUTHOR]

Copyright of Polimery is the property of Industrial Chemistry Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this work, rubber magnetic composites were prepared by incorporation of strontium ferrite into elastomeric matrix based on natural rubber. Cross-linking of the rubbermatrix was performed by using sulfur and peroxide curing system. The study was aimed at the investigation of the type of curing systemand magnetic filler content on curing process and cross-link density of preparedmaterials. Then, the influence of both factors on physical-mechanical andmagnetic properties was observed. The obtained results demonstrate that sulfur-cured composites show better physical-mechanical properties, especially at lower content of strontium ferrite. With increasing amount of ferrite, the differences between the characteristics of both types of composites became less visible, while peroxide-cured sample with maximum ferrite content showed superior tensile strength in comparison with tensile strength of maximally filled sample cured with sulfur system. The obtained results demonstrate better compatibility between the rubber and the filler when peroxide system was introduced for cross-linking of the rubber matrix. [ABSTRACT FROM AUTHOR]

Four different peroxides as curing agents were used to prepare vulcanizates based on natural rubber (NR). The effects of temperature and peroxide concentration on the vulcanization characteristics of rubber compounds, cross-link density ( ν) and physical-mechanical properties of equivalent vulcanizates were investigated. The results revealed that the vulcanization temperature and also the relative amount of peroxide decomposition products are of significant importance in the properties of vulcanizates. Lower vulcanization temperature and lower concentration of peroxides were found to be better factors, showing a proper balance between the degree of cross-linking of the rubber and degradation of the macromolecular chains by side reactions in relation to the crystallization of NR, which imparts vulcanizates based on NR outstanding properties. [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]

Copyright of Polimery is the property of Industrial Chemistry Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]