Correlation between mechanical and microstructural properties of vulcanized polyisoprene, polychloroprene, and nitrile-butadiene rubber subjected to accelerated thermal aging

2018 ◽  
Vol 51 (6) ◽  
pp. 493-511
Author(s):  
Fabián E Hernández ◽  
C Medina ◽  
G Moraga ◽  
J Ramírez ◽  
AF Jaramillo ◽  
...  
Keyword(s):  
Thermal Aging ◽  
Butadiene Rubber ◽  
Raman Analysis ◽  
Elongation At Break ◽  
Vulcanized Rubber ◽  
Peak Intensity ◽  
Link Density ◽  
Cross Link Density ◽  
Mechanical And Microstructural Properties ◽  
Accelerated Thermal Aging

The purpose of this work was to correlate the effects of thermal aging on the macroscopic properties and microstructural changes for three vulcanized rubber types. The materials were subjected to accelerated thermal aging for periods between 0 and 168 h at 100°C. This aging was evaluated by investigating the mechanical properties and by Fourier transform infrared (FTIR) and Raman analysis. The results showed that subjecting the materials to thermal aging for a longer time decreased the elongation at break and tear strength and increased the hardness, while tensile strength exhibited different behavior and followed a different trend. The spectroscopy analyses indicated that there is a decrease in the amount of C=C present in the polymer as the aging time increased, which could be identified by the decrease in peak intensity at 1537 and 1600 cm−1 in the FTIR and Raman spectrum, respectively. These results were attributed mainly to an increase in cross-link density, which caused degradation of the material, essentially by a loss of ductility. A good linear relation ( R2 approximately 0.95) between changes in the intensity of FTIR peaks for the C=C signal and changes in elongation at break and hardness was found, concluding that these are good indicators of degradation in elastomers.

scholarly journals Influence of trans-polyoctylene rubber content on styrene-butadiene rubber properties

2020 ◽  
Vol 13 (1) ◽  
pp. 1-5
Author(s):  
Patrik Macúrik ◽  
Rafal Anyszka ◽  
Ivan Hudec ◽  
Terézia Malčeková ◽  
Ján Kruželák
Keyword(s):  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Curing Time ◽  
Cross Link ◽  
Rubber Content ◽  
Elongation At Break ◽  
Rubber Compounds ◽  
Link Density ◽  
Cross Link Density ◽  
Styrene Butadiene

AbstractThe 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.

Effects of acrylonitrile content on thermal characteristics and thermal aging properties of carbon black-filled NBR composite

2020 ◽  
pp. 009524432094124
Author(s):  
Young Seok Lee ◽  
KiRyong Ha
Keyword(s):  
Thermal Aging ◽  
Aging Process ◽  
Elastic Recovery ◽  
Thermal Characteristics ◽  
Butadiene Rubber ◽  
Cross Link ◽  
Scanning Calorimetry ◽  
Aging Properties ◽  
Link Density ◽  
Cross Link Density

In seal applications, thermal characteristics and thermal aging properties of rubber are essential factors in determining the applicable temperature range and lifetime of the seal. In this study, thermal characteristics and thermal aging properties of the acrylonitrile butadiene rubber composite in response to the acrylonitrile (ACN) content were investigated. Thermal stability, glass transition temperature ( T g), and dynamic property were determined by thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis, respectively. The results showed that T g, thermal decomposition temperature, and tan δ were increased as the ACN content increased. To investigate the thermal aging properties of the composite, the composite was subjected to an accelerated thermal-oxidative and thermal aging process at 100°C for 168 h. The aged composites were evaluated by investigating the change in cross-link density, mechanical properties, and elastic recovery. The change in the chemical functional group was also studied using attenuated total reflectance Fourier transform infrared spectroscopy. The results indicate that subjecting the composite to thermal-oxidative and thermal aging process decreased the elongation at break and elastic recovery, while the cross-link density, Shore A hardness, and 100% modulus were increased. All of the properties were also dependent on the ACN content as well as the aging conditions.

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 Devulcanization of ground tire rubber: microwave and thermomechanical approaches

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Dániel Ábel Simon ◽  
Dávid Zoltán Pirityi ◽  
Tamás Bárány
Keyword(s):  
Microwave Treatment ◽  
Chain Scission ◽  
Polymer Chains ◽  
Tire Rubber ◽  
Ground Tire Rubber ◽  
Elongation At Break ◽  
Link Density ◽  
Cross Links ◽  
Cross Link Density ◽  
Internal Mixer

Abstract We devulcanized ground tire rubber (GTR) in a laboratory microwave oven and an internal mixer, measured the soluble content and the cross-link density of the samples, and then used Horikx’s analysis. The results showed that microwave treatment caused severe degradation of the polymer chains, while in the case of thermomechanical devulcanization, the selective scission of covalent cross-links is more common. Four devulcanized ground tire rubber (dGTR) samples were chosen for further study and three groups of samples were produced: dGTR samples containing vulcanizing agents and different amounts of paraffin oil (dGTR-based mixtures), natural rubber-based rubber mixtures with different dGTR contents and reference rubber mixtures with dGTR-based mixtures (increased vulcanizing agent contents). Cure characteristics showed a plasticizer-like effect of dGTR. Tensile and tear strength decreased drastically with increasing dGTR content; however, elongation at break values did not follow such a trend. Mechanical properties improved with increased vulcanizing agent contents. The examined properties of the samples improved even further with the use of thermomechanically devulcanized samples. Horikx’s analysis showed that this is attributable to moderate polymer chain scission.

scholarly journals Application of Peroxide Curing Systems in Cross-Linking of Rubber Magnets Based on NBR and Barium Ferrite

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Ján Kruželák ◽  
Andrea Kvasničáková ◽  
Elena Medlenová ◽  
Rastislav Dosoudil ◽  
Ivan Hudec
Keyword(s):  
Mechanical Properties ◽  
Barium Ferrite ◽  
Cross Linking ◽  
Butadiene Rubber ◽  
Cross Link ◽  
System Composition ◽  
Peroxide Curing ◽  
Link Density ◽  
Cross Link Density ◽  
Curing Systems

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.

Elongation at Break as a Measure of Cross-Link Density in Vulcanized Elastomers

1966 ◽  
Vol 39 (3) ◽  
pp. 726-739 ◽  
Author(s):  
E. DiGiulio ◽  
G. Bellini ◽  
G. V. Giandinoto
Keyword(s):  
Crosslink Density ◽  
Cross Linking ◽  
Total Degree ◽  
Cross Link ◽  
Elongation Ratio ◽  
Elongation At Break ◽  
Ethylene Propylene ◽  
First Approximation ◽  
Link Density ◽  
Cross Link Density

Abstract After recalling the reaction mechanism suggested for the crosslinking of ethylene propylene copolymers with organic peroxides, the authors consider the relation between concentration of curing agent and crosslink density. It is experimentally found that, as a first approximation, the elongation ratio at break of vulcanizates (unfilled or filled with small quantities of carbon black) is a function of molar concentration of peroxide only: αR=K/P1/2 This relation can be theoretically justified on the basis of the extensibility of polymer chain segments and of the criterion for rupture originally put forward by Taylor and Darin. By applying the above relation to ethylene propylene copolymers it is possible to evaluate the influence of the chain-splitting reaction during cross-linking. The reciprocal of the square of elongation ratio at break (1/αR2) measures the total degree of crosslinking.

Effect of curing systems on vulcanization, mechanical properties, and stress softening of hydrogenated nitrile butadiene rubber vulcanizates

2016 ◽  
Vol 49 (3) ◽  
pp. 243-257 ◽  
Author(s):  
Jianhua Guo ◽  
Zhicai Li ◽  
Xin Zhang
Keyword(s):  
Mechanical Properties ◽  
Dissipated Energy ◽  
Butadiene Rubber ◽  
Stress Softening ◽  
Cyclic Compression ◽  
Nitrile Butadiene Rubber ◽  
Link Density ◽  
Cross Link Density ◽  
Number Of Cycles ◽  
Curing Systems

Hydrogenated nitrile butadiene rubber (HNBR) is cured by sulfur (S), dicumyl peroxide (DCP), and S donor, respectively. Effect of curing systems on vulcanization, mechanical properties, and cyclic compression of HNBR vulcanizates was investigated. The dependence of storage modulus ( G′) on strain was evaluated by Rubber Processing Analysis (RPA) analysis. The Mullins effect and degree of stress softening were also investigated by cyclic compression test. The energy dissipation of cyclic compression was calculated. The presumed mechanism of stress softening of HNBR was presented. The results show that the curing speed, torque, and G′ are higher for S curing system compared with DCP and S donor. The elongation of break and hardness for S system are higher than that of DCP and S donor. The maximum compressive stress, stress softening, and dissipated energy decreased with the increasing number of cycles. The degree of stress softening for S is lower due to the bigger cross-link density and stronger filler–rubber interaction in S-cured HNBR.

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 COMPARATIVE INVESTIGATION OF THE DEVULCANIZATION PARAMETERS OF TIRE RUBBERS

2014 ◽  
Vol 87 (1) ◽  
pp. 31-42 ◽  
Author(s):  
S. Saiwari ◽  
W. K. Dierkes ◽  
J. W. M. Noordermeer
Keyword(s):  
Polymer Network ◽  
Comparative Investigation ◽  
High Ratio ◽  
Styrene Butadiene Rubber ◽  
Process Conditions ◽  
Moderate Increase ◽  
Butadiene Rubber ◽  
Cross Link ◽  
Link Density ◽  
Cross Link Density

ABSTRACT The optimal process conditions for a high ratio of devulcanization to polymer degradation have been investigated for tire rubbers: styrene–butadiene rubber (SBR), butadiene rubber (BR), natural rubber (NR), and chloro-isobutylene–isoprene rubber (CIIR). These polymers all show their own particular breakdown characteristics. The temperature dependence of the breakdown mechanism was investigated by measuring sol fractions and cross-link densities. For SBR and BR, the highest reduction in cross-link density was found at a temperature of 220 °C, together with a moderate increase in sol content. According to the Horikx theory, which correlates sol fraction and a decrease in cross-link density, this is the result of a high degree of cross-link scission. Higher process temperatures result in a lower decrease in cross-link density due to recombination of active chain fragments. NR and CIIR show different behavior. Breakdown of NR in this temperature range results in an almost complete destruction of the polymer network; cross-link density is reduced to almost zero, and the sol fraction is close to 100%. The same result is found for CIIR at higher temperatures. Although different rubbers react via other devulcanization mechanisms, the best devulcanization conditions for whole passenger car tire material are optimized.

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