Ultrasonic Devulcanization of SBR Rubber: Experimentation and Modeling Based on Cavitation and Percolation Theories

1998 ◽  
Vol 71 (2) ◽  
pp. 168-190 ◽  
Author(s):  
S. P. Yushanov ◽  
A. I. Isayev ◽  
S. H. Kim
Keyword(s):  
Shear Rate ◽  
Crosslink Density ◽  
Ultrasonic Waves ◽  
Velocity Shear ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Gel Fraction ◽  
Dependent Viscosity ◽  
Styrene Butadiene ◽  
Unique Relationship

Abstract Continuous ultrasonic devulcanization of styrene-butadiene rubber (SBR) is considered. Experiments are performed under various processing conditions. Two recipes of SBR with different amounts of polysulfidic linkages are utilized. Gel fraction and crosslink density of devulcanized rubbers are measured and a unique relationship between them is established. This relationship is found to be in agreement with the 3D percolation theory. Die characteristics with and without imposition of ultrasonic waves are determined. A modification of acoustic cavitation and flow modeling of ultrasonic devulcanization of SBR is proposed using a concept of effective viscosity characterizing the flow of vulcanized particles before devulcanization combined with a shear rate, temperature, and gel fraction dependent viscosity of devulcanized rubber. Velocity, shear rate, pressure, and temperature field along with gel fraction, crosslink density, and number of bonds broken are simulated. Predicted data on gel fraction, crosslink density, amount of poly-, di- and monosulfidic bonds, and pressure are found to be in qualitative agreement with experimental data.

Morphology and Crystallization Behavior of Lightly Crosslinked Natural Rubber in Blend

2003 ◽  
Vol 76 (5) ◽  
pp. 1164-1176 ◽  
Author(s):  
Tetsuji Kawazura ◽  
Seiichi Kawahara ◽  
Yoshinobu Isono
Keyword(s):  
Natural Rubber ◽  
Homogeneous Nucleation ◽  
Crosslink Density ◽  
Model Compound ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Gel Content ◽  
Gel Fraction ◽  
Compound Model ◽  
Styrene Butadiene

Abstract Isothermal crystallization of natural rubber (NR) dispersed in styrene-butadiene rubber (SBR) was made at −25 °C to investigate effects of both gel fraction of the rubber and morphology of the blend on the crystallization. NR, thus used, was lightly crosslinked model compound (model-NR), which was cured with dicumylperoxide at 160 °C after mastication. The model-NR was mechanically mixed with a large amount of SBR to form droplets of the rubber, a size of which was dependent upon both gel content and crosslink density of the gel fraction. The crystallization of the model-NR in the droplets was quite slow, corresponding to the level reported in the previous work. A rate of crystallization and Avrami exponent were dependent upon the size of the droplets, but not on the gel content and the crosslink density of the model-NR. The suppression in the crystallization was attributed to the homogeneous nucleation occurring in the droplets. This finding was proved, using rubbers obtained from two clones of Hevea brasiliensis, i.e. RRIM600 and RRIM2025, respectively.

Novel modification of styrene butadiene rubber/acrylic rubber blends to improve mechanical, dynamic mechanical, and swelling behavior for oil sealing applications

2021 ◽  
pp. 096739112110313
Author(s):  
Ahmed Abdel-Hakim ◽  
Soma A el-Mogy ◽  
Ahmed I Abou-Kandil
Keyword(s):  
Mechanical Properties ◽  
Crosslink Density ◽  
Physical And Mechanical Properties ◽  
Dynamic Mechanical Properties ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Rubber Blends ◽  
Dynamic Mechanical ◽  
Oil Resistance ◽  
Styrene Butadiene

Blending of rubber is an important route to modify properties of individual elastomeric components in order to obtain optimum chemical, physical, and mechanical properties. In this study, a novel modification of styrene butadiene rubber (SBR) is made by employing acrylic rubber (ACM) to obtain blends of outstanding mechanical, dynamic, and oil resistance properties. In order to achieve those properties, we used a unique vulcanizing system that improves the crosslink density between both polymers and enhances the dynamic mechanical properties as well as its resistance to both motor and break oils. Static mechanical measurements, tensile strength, elongation at break, and hardness are improved together with dynamic mechanical properties investigated using dynamic mechanical analyses. We also proposed a mechanism for the improvement of crosslink density and consequently oil resistance properties. This opens new opportunities for using SBR/ACM blends in oil sealing applications that requires rigorous mechanical and dynamic mechanical properties.

scholarly journals Effects of alkanolamide addition on cure characteristics, crosslink density and tensile properties of carbon-black-filled styrene-butadiene rubber compounds

2018 ◽  
Vol 197 ◽  
pp. 12006 ◽  
Author(s):  
Indra Surya ◽  
Hanafi Ismail
Keyword(s):  
Tensile Strength ◽  
Carbon Black ◽  
Tensile Properties ◽  
Crosslink Density ◽  
Density Measurement ◽  
Tensile Modulus ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Cure Characteristics ◽  
Styrene Butadiene

By using a semi-efficient sulphur vulcanisation system, the effects of alkanolamide (ALK) addition on cure characteristics, crosslink density and tensile properties of carbon black (CB)-filled styrene-butadiene rubber (SBR) compounds were investigated. The ALK was prepared from Refined Bleached Deodorized Palm Stearin and diethanolamine and added into the CB-filled SBR compounds. The ALK loadings were 1.0, 3.0, 5.0 and 7.0 phr. It was found that ALK decreased the scorch and cure times of the CB-filled SBR compounds. ALK also improved the tensile modulus and tensile strength; especially up to a 5.0 phr of loading. The crosslink density measurement proved that the 5.0 phr of ALK exhibited the highest degree of crosslink density which caused the highest in tensile modulus and tensile strength. Due to its plasticity effect, ALK increased the elongation at break of the CB-filled SBR vulcanisates.

Studies on Dicumyl Peroxide Vulcanization of Styrene—Butadiene Rubber in Presence of Sulfur and 2-Mercaptobenzothiazole

1974 ◽  
Vol 47 (2) ◽  
pp. 266-281 ◽  
Author(s):  
C. K. Das ◽  
S. Banerjee
Keyword(s):  
Zinc Oxide ◽  
Stearic Acid ◽  
Crosslink Density ◽  
Addition Reaction ◽  
Styrene Butadiene Rubber ◽  
Methyl Groups ◽  
Butadiene Rubber ◽  
First Order ◽  
First Order Kinetics ◽  
Styrene Butadiene

Abstract The effect of sulfur, MBT, zinc oxide, and stearic acid on the DCP vulcanization of SBR has been studied. DCP decomposition obeys first order kinetics in all cases, but its rate constant is higher in presence of MBT. Sulfur and MBT reduce the crosslink density due to DCP. In the mixes containing sulfur, MBT, zinc oxide, and stearic acid in presence of DCP the crosslink density is initially additive. Here oxidation of some pendent vinyl groups are effected by DCP, and these groups also take part in thiol addition reaction with MBT. The thiazole accelerated sulfuration of SBR proceeds fundamentally by the same mechanism as reported for NR, but the details show slight difference chiefly due to the presence of pendent vinyl groups and styrene units in the chain and due to the absence of pendent methyl groups in SBR.

Evaluation of silane effect as a coupling agent for metakaolin

2019 ◽  
Vol 52 (7) ◽  
pp. 593-608
Author(s):  
Alessandra de Alencar Padua Gabino ◽  
Cléverson Fernandes Senra Gabriel ◽  
Ana Maria Furtado de Sousa ◽  
Cristina Russi Guimarães Furtado ◽  
Bluma Guenther Soares
Keyword(s):  
Crosslink Density ◽  
Coupling Effect ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Reference Compound ◽  
Maximum Torque ◽  
Silica Sample ◽  
Automobile Tire ◽  
Two Samples ◽  
Styrene Butadiene

This study aimed at evaluating the coupling effect of silane Si69 bis(triethoxysilylpropyl)tetrasulfide in metakaolin (MK) in automobile tire tread compounds based on a styrene–butadiene rubber/butadiene rubber blend. A reference compound of a typical tread recipe, filled with silica and carbon black, was used as a reference due to the acknowledged effect of TESPT in silica incorporation in elastomers. A silica sample without silane was also prepared. Silica was then completely substituted by MK, producing two samples, with and without silane. The samples were tested for crosslink density, rheometry, and morphology, and the vulcanization reaction parameters were determined and evaluated. Silane improved the interaction between MK and the polymer matrix, evidenced by the increase in crosslink density and vulcanization reaction rate, the same effect silane causes on silica-filled composites. Morphology also revealed that silane increased MK dispersion and adhesion to rubber. On the other hand, MK seems not to be as reinforcing as silica, considering that maximum torque is related to the stiffness of the material, with MK exhibiting lower values for this parameter.

Viscosity and Molecular Weight of Masticated Styrene-Butadiene Rubber

1965 ◽  
Vol 38 (4) ◽  
pp. 961-966 ◽  
Author(s):  
S. K. Bhatnagar ◽  
S. Banerjee
Keyword(s):  
Molecular Weight ◽  
Intrinsic Viscosity ◽  
Crosslink Density ◽  
Empirical Relation ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Mooney Viscosity ◽  
The Times ◽  
Styrene Butadiene

Abstract Changes in the value of [η], [ηm], K′, (M) and μ of SBR masticated in the cold at 25.0 ± 5.0° C in presence of oxygen with the times of mastication are reported. An empirical relation has been developed between the intrinsic viscosity [η] and Mooney viscosity [ηm] which permits molecular weight of the rubber to be determined directly from Mooney viscosity. The value of g which appears in the Flory equation connecting true crosslink density with the physically determined one has been calculated for unfilled SBR.

Effect of Epoxidized Palm Oil Loading on the Swelling and Mechanical Properties of SBR Vulcanizates

2013 ◽  
Vol 812 ◽  
pp. 236-240
Author(s):  
Mohd Zaki Nurul Ayunie ◽  
Ahmad Zafir Romli ◽  
M.A. Wahab ◽  
Mohd Hanafiah Abidin
Keyword(s):  
Tensile Strength ◽  
Carbon Black ◽  
Palm Oil ◽  
Crosslink Density ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Elongation At Break ◽  
Epoxidized Palm Oil ◽  
Opposite Trend ◽  
Styrene Butadiene

The effects of epoxidized palm oil (EPO) content in carbon black filled styrene butadiene rubber (SBR) on tensile strength, elongation at break and crosslink density were investigated. Five different loadings of EPO in parts per hundred rubbers (phr) were used to test the tensile strength of the carbon black filled SBR which showed a decreasing trend as the content of EPO in the vulcanizates increased. In contrast, elongation at break showed the opposite trend where the elongation at break increased as the content of the EPO increased. The SBR vulcanizates with the highest content of EPO gave the highest value of elongation at break which is 2393.56%. In the case of swelling index, it was found to increase as the amount of EPO increased.

Influence of the silanes on the crosslink density and crosslink structure of silica-filled solution styrene butadiene rubber compounds

2016 ◽  
Vol 24 (7) ◽  
pp. 711-727 ◽  
Author(s):  
Jong-Yeop Lee ◽  
Nam Park ◽  
Seokhwan Lim ◽  
Byeongkyu Ahn ◽  
Woong Kim ◽  
...  
Keyword(s):  
Crosslink Density ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Rubber Compounds ◽  
Styrene Butadiene

A Model for Rubber Degradation under Ultrasonic Treatment: Part II. Rupture of Rubber Network and Comparison with Experiments

2000 ◽  
Vol 73 (2) ◽  
pp. 325-339 ◽  
Author(s):  
V. V. Yashin ◽  
A. I. Isayev
Keyword(s):  
Crosslink Density ◽  
Theoretical Data ◽  
High Amplitude ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Irreversible Effects ◽  
Residual Deformations ◽  
Styrene Butadiene ◽  
Good Agreement ◽  
Rubber Degradation

Abstract A simple theoretical model of network degradation around ultrasonically pulsating cavities is considered. The model is based on the concept of overstressed chains and provides a simple tool to estimate a number of chains which should be involved in mechanochemical degradation at a given amplitude of ultrasonic pulsation. High amplitude cavitation with no collapse-like effects is demonstrated to result in significant reduction of the rubber crosslink density. This model also predicts considerable effects of rubber degradation on elastic properties of rubber around a pulsating cavity including certain irreversible effects and residual deformations. The Dobson—Gordon theory of rubber network statistics is employed in order to interpret the experimental data on the dependence of gel fraction in devulcanized rubbers on crosslink density in the gel. Application of the approach to devulcanized styrene—butadiene rubber (SBR) and silicone rubber demonstrates that the assumption on spatial—temporal randomness of rubber degradation allows us to achieve a fairly good agreement between experimental and theoretical data.

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