New binary accelerator systems for sulphur vulcanisation of styrene butadiene rubber

Abstract

It is suggested that binary systems of rubber vulcanisation containing thiourea proceed by a nucleophilic reaction mechanism. The exact mechanism of the chemical reactions involved when binary accelerator systems are used in rubber vulcanisation is not fully understood even now. It differs with the systems and the nature of the elastomer used. In the present work, a derivative of thiourea, N-amidino N'-phenyl thiourea (APT), was studied as a secondary accelerator along with tetramethyl thiuram disulphide (TMTD)/mercaptobenzothiazyl disulphide (MBTS) in the sulphur vulcanisation of styrene butadiene rubber. Thiourea binary systems were used as controls. The binary systems containing APT are very effective in reducing the optimum vulcanisation time. APT being more nucleophilic than thiourea, is more reactive here (as observed by the reduction in cure time). A nucleophilic reaction mechanism is indicated in the vulcanisation reaction under review. Different concentrations of APT were tried in various mixes using standard recipes, and reference mixes were also evaluated. The optimum dosage of APT required has been derived based on the cure characteristics of the mixes and the physical properties of the vulcanisates.     

Preparation and characterization of exfoliated graphite and its styrene butadiene rubber nanocomposites

Nanocomposites consisting of styrene butadiene rubber (SBR) reinforced with the modified-graphite and natural-graphite with concentrations of 5 wt% were fabricated. Processing techniques such as acid treatment, thermal shock, sonication were employed in the fabrication of modified-graphite.The graphite platelets oxidized using sulfuric and nitric acids were analyzed by the Raman scattering, Fourier transformed infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The FT-IR results indicate the presence of acid groups in the treated samples, and Raman spectroscopy of acid-graphite platelets further corroborate the formation of surface defect due to the introduction of functional groups. However, the structure of XRD peaks did not change irrespective of processing techniques.The SBR-based nanocomposites were characterized using the scanning electron microscopy (SEM), rheometer, Instron tensile machine, thermal and electrical analyser.The results showed that nanocomposites onto acid-graphite platelets enhanced mechanical properties and fatigue properties of nanocomposites compared to those containing natural-graphite due to the increase in the interaction between the polymer and the modified-graphite. And the dynamic properties of nanocomposites had no influence according to the processing techniques. Also, thermal and electrical properties of nanocomposites using acid-graphite platelets were enhanced due to the broadened specific surface by the acid treatment.     

Effect of chemical treatment of wood flour on the properties of styrene butadiene rubber/polystyrene composites

Composites from SBR/PS blend and the chemically treated wood flour have been prepared. The materials used for such treatment are NaOH, MAN, MAN‐glycidyl methacrylate, and silane coupling agent, used to improve the dispersion of wood flour in the SBR/PS blend. The effects of chemical treatment on curing characteristics, and physicomechanical and electrical properties of SBR/PS composites were studied. The rheological as well as the mechanical parameters were improved by using the modified wood flour with MAN‐glycidyl methacrylate (SMG), followed by SM obtained at 15 phr, while the other treatments slightly affect these parameters. The permittivity ?′ and dielectric loss ?″ were measured in the frequency range from 100 Hz up to 100 kHz and at temperatures ranging from 30 up to 90°C. The dielectric investigations indicate that the samples containing wood flour treated with both SMG and SM increase the values of ?′ and decrease those of ?″, which allow such samples to be used in insulation purposes. The increase in the relaxation time and the crosslinking density ν for such composites indicate the increase in filler–polymer interaction rather than filler–filler interaction. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5861–5870, 2006     

碱法制备蔗渣纳米纤维素/丁苯橡胶复合材料性能

针对目前硫酸法制备纳米纤维素高污染、高危险、高处理成本的缺点,采用环境友好、低能耗、低成本的碱法从蔗渣中制备纳米纤维素（2-BNC）,补强丁苯橡胶（SBR）,并与硫酸法制备的纳米纤维素（S-BNC）以及白炭黑（silica）补强SBR的性能进行对比,探究2-BNC的加入对复合材料性能的影响。结果表明,2-BNC在基体中的分散性优于silica,与SBR基体有良好的界面结合,在同等填料份数下,SBR/2-BNC硫化胶的储能模量高于SBR/silica硫化胶,损耗因子下降,耐磨耗性能更加突出,且力学性能更佳;2-BNC和S-BNC对SBR的整体补强效果相当。     

About the activation energies of the main and secondary relaxations in cured styrene butadiene rubber

This article studies the influence of the network structure on the activation energies of the α and β relaxations in vulcanized styrene butadiene rubber, SBR. A cure system based on sulphur and TBBS (N‐t‐butyl‐2‐benzothiazole sulfenamide) was used in the formulation of several compounds cured at 433 K. The activation energies were evaluated from internal friction (loss tangent) data of the compounds using an automated subresonant forced pendulum in a wide frequency range and between 80 K and 273 K. The internal friction data of the samples reveal two transitions, α and β, characterized by the temperatures T_α and T_β, due to the glass transition and the phenyl group rotation of the copolymer, respectively. Although T_α increases at higher crosslink density, it shows also a dependence with the amount of polysulphide and monosulphide linkages present in the samples. The highest activation energy for this process is obtained for the samples with high crosslink density and 30% of monosulphides in this structure. In the case of the β‐relaxation, there is a pronounced change in the activation energy between the uncured and the cured samples. The type of structure formed during vulcanization has an important effect in the activation energy of the segmental mode‐process. In the case of the β‐process, the cis‐trans isomerization that takes place during vulcanization in the butadiene part of the SBR, might be the cause of conformational changes in the surrounding of the phenyl rings that affect the energy barrier associated to the phenyl rotation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Grafting hydroxy‐terminated polybutadiene onto nanosilica surface for styrene butadiene rubber compounds

Hydroxy teminated polybutadiene (HTPB) was grafted onto the surface of nanosilica particles via toluene di‐isocyanate (TDI) bridging to reduce filler–filler interactions and improve dispersion of nanosilica in rubber. Also, this prepolymer as modifier contains double bonds which participate in sulfur curing of styrene butadiene rubber (SBR) matrix to enhance filler/polymer interaction and reinforcement effects of silica. The reactions were characterized by titration and Fourier transforms infrared spectroscopy. Thermogravimetric analysis was utilized to evaluate the weight percentage of grafted TDI and HTPB. About 60% of the hydroxyl sites of silica were reacted with excess TDI in the first reaction. In the second reaction, HTPB as desired reactive coating was grafted on the functionalized nanosilica to constitute about 24 wt % of the final modified silica. The sedimentation experiments showed good suspension stability for the modified nanosilica in the organic media. Scanning electron microscopy revealed nanoscale dispersion of modified silica aggregates in the SBR matrix at concentration of about 14 phr. Also, vulcanization characteristics and mechanical properties of compounds demonstrated that HTPB grafting improved dispersion of nanosilica as well as its interaction to the rubber matrix as an efficient reinforcement. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Sequential interpenetrating polymer network based on styrene butadiene rubber and polyalkyl methacrylates

A series of sequential interpenetrating polymer network (IPNs) based on styrene butadiene rubber (SBR) and polyalkyl (methyl, ethyl, and butyl) methacrylates have been prepared by using tetraethylene glycol dimethacrylate as crosslinker. The IPNs were characterized by infrared spectrophotometer, dynamic mechanical analyzer, thermogravimetric analyzer, and swelling study. IPNs have exhibited higher tensile properties compared with pure SBR. IPNs based on PMMA have shown higher tensile strength compared with others. Dynamic mechanical analysis has shown that the IPNs have superior dynamic properties than SBR. Because of IPN formation, tan δ peak shifted inward between SBR and acrylates. Although the magnitude of tan δ decreased, the peaks were broadened because of micro heterogeneous phase separation. At higher concentration of methacrylate, splitting in tan δ peak was noticed because of phase separation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1120–1126, 2007     

凝聚母液pH值的变化对环保型丁苯橡胶SBR1502E性能的影响

以中国石油吉林石化公司环保型丁苯橡胶SBR1502E为研究对象,研究了凝聚母液在不同pH值下对胶性能的影响.结果表明,在不改变母液温度、胶液进料量、高分子絮凝剂加入量情况下,凝聚母液pH值的变化对胶的性能产生较大影响,当初始pH值为3.0～3.5时,环保型丁苯橡胶SBR1502E的性能全部达到优级品技术标准.     

Tear and processing behaviour of short sisal fibre reinforced styrene butadiene rubber composites

The tear failure and processing characteristics of short sisal fibre reinforced styrene butadiene rubber (SBR) composites were investigated. Tear strength was examined with special reference to the effects of fibre length, fibre orientation, fibre concentration and bonding agent. It was observed that the tear strength depends on all the above factors. The tear failure mechanism was analysed from fractographs taken using a scanning electron microscope (SEM). During tear testing, the composites failed by a shearing process. Microscopic examination of cracks propagating in SBR composites revealed that the amorphous SBR matrix developed cracks, leaving ligaments of rubber attached to the broken fibres. The rubber particles were stretched as the crack opened and failure occurred at large critical extensions. It was observed that an increase in the concentration of fibres increased the tear strength in both longitudinal and transverse directions. The tear strength values were almost three to four times higher than those of the unfilled vulcanizates under similar conditions. In order to analyse the processing behaviour, the green strength, mill shrinkage and Mooney viscosity of the compounds were determined. Finally, the polymer–filler interaction was studied using the Lorenz–Park and Kraus equations.     

Analysis of network structure formed in styrene–butadiene rubber cured with sulfur/TBBS system

Several styrene–butadiene rubber (SBR) compounds were prepared with different cure systems based on sulfur and TBBS (N‐t‐butyl‐2‐benzothiazole sulfenamide), varying the amount of sulfur and accelerator between 0.5 and 2.5 phr in the formulation. Torque curves, measured with a moving die rheometer at temperatures at 433 K, were used to characterize the vulcanization. The time to achieve the maximum torque, t_100%, was evaluated for each sample, and this time was set to vulcanize sheets at 433 K. The density and type of elastically active crosslinks of each cured sample were evaluated by means of swelling measurements and were related to the vulcanizing system. Finally, the rheometer data were analyzed considering the network structure formed during vulcanization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1105–1112, 2007     

Investigating the effect of the degree of cross-linking in styrene butadiene rubber on the performance of graphite anodes for the use in lithium-ion batteries

Carboxymethyl cellulose/styrene butadiene rubber (CMC/SBR) has been proven to be an effective binder system for the use of graphite anodes within the lithium-ion battery industry. However, often when this system is employed, there is no acknowledgement regarding the specific chemistry of the SBR used. This is an important omission because properties such as glass transition temperatures and tensile strengths are heavily dependent on the ratio of styrene to butadiene content and the degree of cross-linking within the SBR. In this study, we investigate the impact of using styrene butadiene rubbers (SBRs) with different degrees of cross-linking on the performance of graphite anodes. We demonstrate that SBRs with a higher degree of cross-linking provide longer and more stable capacity retentions, than SBRs with a lower degree of cross-linking. This was found to correlate with the adhesion and cohesion strengths of the electrode coatings, and the degree of electrolyte swelling the SBRs systems undertook. Overall, the findings from this study indicate that the degree of cross-linking within the SBR impacts the overall performance of the battery.     

Effect of epoxidized natural rubber on thermal properties,fatigue life,and natural weathering test of styrene butadiene rubber/recycled acrylonitrile‐butadiene rubber (SBR/NBRr) blends

The utilization of waste rubber powder in polymer matrices provides an attractive strategy for polymer waste disposal. Addition of recycled acrylonitrile‐butadiene rubber (NBRr) in rubber compounds gives economic (lowering the cost of rubber compounds) as well as processing advantages. In this study, the properties of styrene butadiene rubber (SBR)/NBRr blends with and without epoxidized natural rubber (ENR‐50) as a compatibilizer were determined. The results such as thermal gravimetric analysis (TGA), fatigue life, and natural weathering test of SBR/NBRr blends with and without ENR‐50 were carried out. Results showed that TG thermograms of SBR/NBRr blends with ENR‐50 show lower thermal stability compared blends without ENR‐50. The incorporation of ENR‐50 into SBR/NBRr blends has reduced char residue compared SBR/NBRr blends without ENR‐50. The incorporation of ENR‐50 in SBR/NBRr blends has increased the rigidity of the blends thus lowering the fatigue life. The increment in tensile properties retention of SBR/NBRr blends with ENR‐50 indicated the enhancement on weathering resistant. The surfaces of SBR/NBRr blends with ENR‐50 after 6 months exposure showed a minimal severity of crack compared with SBR/NBRr blends without ENR‐50. It revealed that the scale of cracks has reduced indicating well‐retaining interfacial adhesion between SBR and NBRr with the presence of ENR‐50 as a compatibilizer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

埃洛石纳米管对丁苯橡胶的增强作用

研究了未经表面改性和用双-[3-(三乙氧基硅)丙基]四硫化物(Sj-69)改性的埃洛石纳米管(HNTs)对丁苯橡胶(SBR)硫化胶力学性能的影响及其微观形貌.结果表明,HNTs对SBR具有明显的增强作用;Si-69能进一步提高其增强效果,有效地改善HN/s在橡胶基体中的分散,并能降低SBR/HN了s硫化胶的滚动阻力和动态生热.     

Some considerations concerning the dynamic mechanical properties of cured styrene–butadiene rubber/polybutadiene blends

The dynamic mechanical response of several binary mixtures of a styrene–butadiene copolymer and high cis‐polybutadiene has been studied. The loss tangent and shear modulus were measured with a free damping torsion pendulum at temperatures between 143 and 343 K in argon atmosphere. From the loss tangent data the glass transition temperature of each sample was evaluated. The results can be represented by the Fox equation that relates the glass transition temperature of the blend with that of constituent polymers. The influence in the loss tangent data of the crystallization of the high cis BR used in the blend is discussed. A study of the separation of the crystalline and amorphous parts in the polybutadiene using the storage modulus data is presented. Finally, the loss of crystallinity at different contents of SBR in the blend is analysed using the dynamic mechanical data. © 2000 Society of Chemical Industry     

丁苯橡胶生产及市场分析

综述了国内外丁苯橡胶（SBR）的生产及市场情况,对国内SBR的市场发展趋势进行了分析。并预测在世界金融危机的影响下,国内SBR需求增长将会放缓,而国内产能的猛增,将加剧SBR产能过剩,造成供过于求的局面。此外,本文还对国内SBR行业存在的不足提出了几点建议。     

Effect of ingredients on the electrical conductivity of styrene butadiene rubber

The effect of different ingredients, which are usually added during the preparation of rubber mixtures, on the electrical conductivity σ of styrene-butadiene rubber (SBR-1502) has been studied. It was found that processing oil (as softener) showed a marked increase in σ with respect to the pure sample. Stearic acid (as antioxidant), however, did not show a considerable effect on σ. The addition of constant concentration of 50 phr from different types of carbon black (filler) namely, ISAF, HAF, FEF and SRF to the rubber matrix resulted in different values of the initial conductivity of the vulcanized samples. The conduction mechanism through carbon black-loaded rubber vulcanizates has been discussed and rough estimation of the separation distance between carbon black particles (or aggregates) suggested. The carbon black-loaded rubber vulcanizates showed a reasonable stability and reproducibility of σ after pre-thermal-oxidative ageing at 365 K for 30 days.     

SMC晶须在丁苯橡胶中的应用

对硅镁钙晶须（SMC晶须）在丁苯橡胶（SBR）中的应用进行了研究,考察了晶须用量（0～50phr）对胶料的硫化特性和硫化胶的力学性能的影响,并与常用的填料白炭黑（WCB）和碳酸钙（CaCO3）进行了比较。实验结果表明：SMC晶须对SBR有促进硫化作用;SMC晶须对SBR具有一定的补强作用,拉伸强度随着晶须用量的增加而增大;用量相同时,SMC晶须填充的复合材料硬度和撕裂强度与WCB填充的相当,300%定伸应力比WCB填充的高,拉伸永久变形比WCB小得多;SMC晶须补强效果远优于CaCO3。     

Vulcanization kinetics of nano-silica filled styrene butadiene rubber

It was shown that the physical filler-polymer and filler–filler interactions, apart from the filler surface chemistry, has a substantial role in controlling the vulcanization kinetics of styrene butadiene rubber filled with nano-silica in a sulfur vulcanization system. Kinetic studies by the oscillating disc rheometer, differential scanning calorimeter, and swelling tests revealed that the vulcanization rate goes through a maximum as loading of silica increases, but conversion in crosslinking continuously decreases as the amount of silica increases. The effect of silica loadings on the vulcanization reactions was linked to the immobilization of rubber chains around particles as well as in a polymer-mediated filler network, which were differentiated by the nonlinear viscoelastic behavior of rubber vulcanizates. By surface modification of nano-silica, the accelerating/decelerating effects of nano-silica on the vulcanization reactions were altered corresponding to the non-linear viscoelastic behavior of the vulcanizates. Therefore, a mechanism was proposed which correlates vulcanization kinetics of rubber to the dynamics of chains influenced by the reinforcing fillers.     

丁苯橡胶生产及市场分析

综述了国内外丁苯橡胶的生产及市场情况,对国内丁苯橡胶的市场发展趋势进行了分析。此外,还对国内丁苯橡胶行业存在的不足提出了几点建议。