scholarly journals Magnetic composites based on NR and strontium ferrite

2019 ◽  
Vol 12 (1) ◽  
pp. 63-69
Author(s):  
Ján Kruželák ◽  
Andrea Kvasničáková ◽  
Rastislav Dosoudil ◽  
Ivan Hudec
Keyword(s):  
Carbon Black ◽  
Strontium Ferrite ◽  
Rubber Matrix ◽  
Cross Link ◽  
Magnetic Composites ◽  
Link Density ◽  
Cross Links ◽  
Cross Link Density ◽  
The Cross ◽  
Thermo Physical Properties

Abstract 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.

Thermooxidative aging of rubber composites based on NR and NBR with incorporated strontium ferrite

2017 ◽  
Vol 50 (1) ◽  
pp. 71-91 ◽  
Author(s):  
Ján Kruželák ◽  
Rastislav Dosoudil ◽  
Ivan Hudec
Keyword(s):  
Strontium Ferrite ◽  
Rubber Matrix ◽  
Magnetic Characteristics ◽  
Butadiene Rubber ◽  
Cross Link ◽  
Magnetic Composites ◽  
Aging Period ◽  
Link Density ◽  
Cross Link Density ◽  
The Cross

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.

scholarly journals Rubber Composites Based on Polar Elastomers with Incorporated Modified and Unmodified Magnetic Filler

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Ján Kruželák ◽  
Richard Sýkora ◽  
Rastislav Dosoudil ◽  
Ivan Hudec
Keyword(s):  
Sem Analysis ◽  
Strontium Ferrite ◽  
Rubber Matrix ◽  
Cross Link ◽  
Magnetic Composites ◽  
Link Density ◽  
Cross Link Density ◽  
Surface Modified ◽  
Properties Of Composites

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.

Barium and strontium ferrite-filled composites based on NBR and SBR

2018 ◽  
Vol 51 (5) ◽  
pp. 421-439 ◽  
Author(s):  
Ján Kruželák ◽  
Martina Matvejová ◽  
Rastislav Dosoudil ◽  
Ivan Hudec
Keyword(s):  
Barium Ferrite ◽  
Strontium Ferrite ◽  
Styrene Butadiene Rubber ◽  
Magnetic Characteristics ◽  
Butadiene Rubber ◽  
Magnetic Composites ◽  
Link Density ◽  
Cross Link Density ◽  
The Cross ◽  
Styrene Butadiene

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.

scholarly journals Influence of the chemical structure of cross-linking agents on properties of thermally reversible networks

2016 ◽  
Vol 88 (12) ◽  
pp. 1103-1116 ◽  
Author(s):  
Lorenzo Massimo Polgar ◽  
Robin R.J. Cerpentier ◽  
Gijs H. Vermeij ◽  
Francesco Picchioni ◽  
Martin van Duin
Keyword(s):  
Chemical Structure ◽  
Chemical Conversion ◽  
Rubber Matrix ◽  
Cross Linking ◽  
Cross Link ◽  
Molar Amount ◽  
Link Density ◽  
Cross Link Density ◽  
Cross Linker ◽  
The Cross

Abstract It is well-known that the properties of cross-linked rubbers are strongly affected by the cross-link density. In this work it is shown that for thermoreversibly cross-linked elastomers, the type and length of the cross-linker also have a significant effect. A homologous series of diamine and bismaleimide cross-linkers was used to cross-link maleic-anhydride-grafted EPM irreversibly and furan-modified EPM thermoreversibly, respectively. Bismaleimide cross-linkers with a polarity close to that of EPM and a relatively low melting point have a better solubility in the rubber matrix, which results in higher chemical conversion and, thus, higher cross-link densities at the same molar amount of cross-linker. Samples cross-linked with different spacers (aromatic and aliphatic spacers of different lengths) were compared at the same cross-link density to interpret the effects on the material properties. The rigid character of the short aliphatic and the aromatic cross-linkers accounts for the observed increase in hardness, Young´s modulus and tensile strength with respect to the longer, more flexible aliphatic cross-linkers. In conclusion, the structure of the cross-linking agent can be considered as an alternative variable in tuning the rubber properties, especially for thermoreversibly cross-linked rubber.

ENTANGLED NETWORK INFLUENCED BY CARBON BLACK IN SOLUTION SBR VULCANIZATES REVEALED BY THEORY AND EXPERIMENT

2020 ◽  
pp. 000-000
Author(s):  
Abhay Kumar ◽  
Mahawat Singh Dalmiya ◽  
Mohit Goswami ◽  
Vidit Bansal ◽  
Sharad Goyal ◽  
...  
Keyword(s):  
Carbon Black ◽  
Uniaxial Stress ◽  
Microscopy Study ◽  
Rubber Matrix ◽  
Cross Link ◽  
Force Microscopy ◽  
Link Density ◽  
Density Values ◽  
Cross Link Density ◽  
Physical Entanglement

ABSTRACT The contribution of carbon black (CB) on changes in cross-link density and physical entanglement has been quantified by swelling and uniaxial stress–strain measurements considering Mooney–Rivlin parameters. Solution SBR (SSBR) vulcanizates with varying content of high abrasion furnace (HAF) CB were studied. Rubber–filler networks increase the cross-link density values, which were determined by using Flory–Rehner and modified Guth–Gold equations by equilibrium swelling study. The Mooney–Rivlin parameter C1 was quantified using cross-link density, whereas parameter C2, representing physical entanglement, was determined for filled rubber by correlating with tensile results. The parameter C2 is monitored to be decreased with increasing CB (HAF) loading. A simple parabolic trend for physical entanglement parameter with increasing CB loading is proposed, and it shows a correlation coefficient of 0.99595. Atomic force microscopy study confirms the generation of filler networking in the rubber matrix. The current findings elucidate a way for quantifying physical network changes due to fillers in an unfilled rubber system.

Combined sulfur and peroxide curing systems applied in cross-linking of rubber magnets

2020 ◽  
pp. 096739112095650
Author(s):  
Ján Kruželák ◽  
Andrea Kvasničáková ◽  
Rastislav Dosoudil ◽  
Ivan Hudec ◽  
Jarmila Vilčáková
Keyword(s):  
Rubber Matrix ◽  
Magnetic Characteristics ◽  
Cross Linking ◽  
Magnetic Composites ◽  
Peroxide Curing ◽  
Link Density ◽  
Strong Adhesion ◽  
Cross Links ◽  
Cross Link Density ◽  
Curing Systems

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.

STABLE FREE RADICAL–ASSISTED MECHANICAL DEVULCANIZATION OF CARBON BLACK–FILLED NATURAL RUBBER VULCANIZATES

2018 ◽  
Vol 91 (2) ◽  
pp. 469-491
Author(s):  
Anu Mary Joseph ◽  
K. N. Madhusoodhanan ◽  
Rosamma Alex ◽  
Benny George
Keyword(s):  
Free Radical ◽  
Carbon Black ◽  
Decisive Role ◽  
Ambient Conditions ◽  
Cross Link ◽  
Stable Free Radical ◽  
Link Type ◽  
Link Density ◽  
Cross Links ◽  
Cross Link Density

ABSTRACT The issue of recombining of the radicals formed from cross-link scission and the consequent reformation of once-cleaved cross-links during mechanical devulcanization of carbon black–filled NR vulcanizates was investigated in a two-roll mill by the addition of the stable free radical 4-hydroxy-TEMPO (4HT), formerly 4-hydroxy-2, 2, 6, 6-tetramethylpiperidine-N-oxyl free radical. The effect of concentration of 4HT (0–6 pounds per hundred of rubber [phr]) and the effect of cure system, that is, conventional, semi-efficient (EV), and EV, used for vulcanization of the original sample on the efficiency of devulcanization were determined from the residual cross-link density of the gel part of the devulcanized rubber and the percent devulcanization, and further from revulcanizate properties. Chemical probe analysis of the devulcanized sample disclosed that (i) mechanical shearing predominantly breaks the majority cross-link type that decides the associated percent devulcanization; (ii) shear-induced chain-shortening reactions of polysulfidic cross-links occur at ambient conditions, increasing the absolute value of monosulfidic links irrespective of the significant reduction in total cross-link density due to cross-link scission; (iii) re–cross-linking of once cleaved bonds is being arrested in the presence of 4HT, thereby increasing the percent devulcanization. Both the bond energy of the cross-link type to be cleaved and the recombining capacity of the broken cross-links seem to play a decisive role in percent devulcanization, and the probable mechanism involved is suggested.

Relationship between the cross-link structure and properties of peroxide and sulfur-cured magnetic composites based on NR and NBR

2016 ◽  
Vol 49 (6) ◽  
pp. 459-480 ◽  
Author(s):  
Ján Kruželák ◽  
Richard Sýkora ◽  
Rastislav Dosoudil ◽  
Ivan Hudec
Keyword(s):  
Cross Linking ◽  
Butadiene Rubber ◽  
Cross Link ◽  
Magnetic Composites ◽  
Link Structure ◽  
Link Density ◽  
Cross Link Density ◽  
The Cross ◽  
The Relationship ◽  
Curing Systems

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.

COMPARISON OF STRUCTURE AND PROPERTIES OF TWO STYRENE–BUTADIENE RUBBERS FILLED WITH CARBON BLACK, CARBON–SILICA DUAL-PHASE FILLER, AND SILICA

2013 ◽  
Vol 86 (4) ◽  
pp. 664-678 ◽  
Author(s):  
Jian-Hua Ma ◽  
Su-He Zhao ◽  
Li-Qun Zhang ◽  
You-Ping Wu
Keyword(s):  
Carbon Black ◽  
Heat Generation ◽  
Rubber Matrix ◽  
Dual Phase ◽  
Cross Link ◽  
Link Density ◽  
Cross Link Density ◽  
Styrene Butadiene ◽  
Filled Composite ◽  
Heat Buildup

ABSTRACT Heat buildup, wet skid resistance (WSR), wear resistance (WR), and cutting and chipping resistance (CCR) of carbon black (CB), carbon–silica dual-phase filler (CSDPF), and silica-filled two kinds of styrene–butadiene rubber (SBR) were investigated. For the same SBR systems, the composite filled with silica exhibited the lowest heat generation and highest WSR performance, whereas it showed the worst WR and CCR among the three composites. The CSDPF-filled composite obtained a balanced overall performance. Rubber processing analyzer (RPA) strain sweep results showed that the CSDPF-filled composite exhibits the lowest Payne effect, which is related to filler networking in the rubber matrix. Solid-state 1H low-field NMR demonstrated that the sequence of the filler–rubber interaction of the composites was CB > CSDPF > silica. Bis-(3-(triethoxysilyl)-propyl)-tetrasulfide increased the cross-link density of the silica-filled composite. For the composites with different fillers, the lower filler network structure and higher cross-link density result in the lowest heat generation of silica-filled composite, and the strongest filler–rubber interaction leads to the best WR and CCR performances of the CB-filled composite. Filled SBR5025 composites exhibited better WR, lower heat buildup, and worse CCR than filled SBR1712 composites with the same filler.

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