Showing papers on "Styrene-butadiene published in 2015"

The filler–rubber interface in styrene butadiene nanocomposites with anisotropic silica particles: morphology and dynamic properties

Abstract: Silica–styrene butadiene rubber (SBR) nanocomposites were prepared by using shape-controlled spherical and rod-like silica nanoparticles (NPs) with different aspect ratios (AR = 1–5), obtained by a sol–gel route assisted by a structure directing agent. The nanocomposites were used as models to study the influence of the particle shape on the formation of nanoscale immobilized rubber at the silica-rubber interface and its effect on the dynamic-mechanical behavior. TEM and AFM tapping mode analyses of nanocomposites demonstrated that the silica particles are surrounded by a rubber layer immobilized at the particle surface. The spherical filler showed small contact zones between neighboring particles in contact with thin rubber layers, while anisotropic particles (AR > 2) formed domains of rods preferentially aligned along the main axis. A detailed analysis of the polymer chain mobility by different time domain nuclear magnetic resonance (TD-NMR) techniques evidenced a population of rigid rubber chains surrounding particles, whose amount increases with the particle anisotropy, even in the absence of significant differences in terms of chemical crosslinking. Dynamic measurements demonstrate that rod-like particles induce stronger reinforcement of rubber, increasing with the AR. This was related to the self-alignment of the anisotropic silica particles in domains able to immobilize rubber.

Glass Transition and Molecular Mobility in Styrene–Butadiene Rubber Modified Asphalt

Abstract: Asphalt, a soft matter consisting of more than a thousand chemical species, is of vital importance for the transportation infrastructure, yet it poses significant challenges for microscopic theory and modeling approaches due to its multicomponent nature. Polymeric additives can potentially enhance the thermo-mechanical properties of asphalt, thus helping reduce the road repair costs; rational design of such systems requires knowledge of the molecular structure and dynamics of these systems. We have used molecular dynamics (MD) simulations to investigate the volumetric, structural, and dynamic properties of the neat asphalt as well as styrene–butadiene rubber (SBR) modified asphalt systems. The volume–temperature behavior of the asphalt systems exhibited a glass transition phenomenon, akin to that observed in experiments. The glass transition temperature, room temperature density, and coefficient of volume thermal expansion of the neat asphalt systems so evaluated were in agreement with experimental data w...

Transport characteristics of organic solvents through carbon nanotube filled styrene butadiene rubber nanocomposites: the influence of rubber–filler interaction, the degree of reinforcement and morphology

Abstract: The transport behaviour of some aromatic and aliphatic solvents through carbon nanotube filled styrene butadiene rubber composites has been investigated. The aim of the present work is to investigate the role of the sorption technique in analysing the compatibility and the reinforcing effect of MWCNTs as a filler in the SBR matrix. It also focuses on the investigation of the relationship between the dispersion of CNTs in the SBR matrix and its transport behaviour. The diffusion and transport of organic solvents through the membranes have been investigated in detail as a function of CNT content, nature of solvent and temperature in the range of 28–60 °C. Solvent uptake, diffusion, sorption and permeation constants were investigated and were found to decrease with the increase of CNT loading. Transport properties could be related to the morphology of the nanocomposites. At high concentration CNT particles form a local filler–filler network in the rubber matrix. As a result, the transport of solvent molecules through the polymer is hindered. The rubber–solvent interaction parameter, enthalpy and entropy of sorption have also been estimated from the transport data. The values of rubber–solvent interaction parameters obtained from the diffusion experiments have been used to calculate the molecular mass between the crosslinks of the network polymer. The better reinforcement at higher filler loading was confirmed from the cross-link density values. The extent of reinforcement was evaluated using Kraus and Cunneen and Russel equations. The Affine and Phantom models for chemical crosslinks were used to predict the mobility of the crosslinks. The Phantom model gave better fitting indicating that the chains can move freely through one another, i.e. the junction points fluctuate over time around their mean position without any hindrance from the neighbouring molecule. The diffusivity datas of the systems have shown dependence on the temperature and microstructure of the nanocomposite. Finally, the diffusion data have been compared with theoretical predictions.

Construction of an Interconnected Nanostructured Carbon Black Network: Development of Highly Stretchable and Robust Elastomeric Conductors

Abstract: In the present work, a strong filler–filler network of conductive carbon black was strategically established in an elastomer matrix, which leads to a unique combination of electrical and mechanical properties. The novelty of our composites was the development of a strong percolated morphology of nanostructured conducting carbon black particles by the incorporation of relatively large nonreinforcing spherical silica particles, inside the soft elastomer matrix. This technique allowed us to fabricate solution styrene butadiene rubber (S-SBR) composites with outstanding electrical conductivity of 40 S/m, tensile strength ∼10 MPa, and extensibility up to 200%. Furthermore, the electrical conductivity was strain-independent up to 50% elongation strain. The electrical conductivity was found to be unaltered after 2000 loading–unloading cycles. This is the first ever report of a robust elastomeric system with such high electrical conductivity where all the basic ingredients used were selected from well-known comme...

Devulcanization of styrene butadiene rubber by microwave energy: Effect of the presence of ionic liquid

Abstract: In this study, styrene butadiene rubber (SBR) was devulcanized using microwave irradiation. In particular, effect of ionic liquid (IL), pyrrolidinium hydrogen sulfate [Pyrr][HSO4], on the devulcanization performance was studied. It was observed that the evolution of the temperature reached by rubber powder exposed to microwave irradiation for different energy values was favored by the presence of ionic liquid [Pyrr][HSO4] significantly over the whole range of the microwave energy values. Beyond the threshold point of 220 Wh/kg, the soluble fraction after devulcanization sharply increased with increasing devulcanization microwave energy. For the powder mixed with [Pyrr][HSO4], the increase was more significant. Furthermore, the crosslink density was observed to decrease slowly with the microwave energy up to 220 Wh/kg, beyond which the crosslink density decreased significantly for the rubber impregnated with IL. For the rubber with IL, significant and continuous increase in Tg with microwave energy values was observed in comparison with the SBR where no change in transition temperature was observed. Mechanical shearing of rubber gums in the two-roll mill favored the devulcanization process, which indicated that the combination of mechanical loading with microwave energy and IL is an efficient procedure allowing an optimal devulcanization of rubbers.

Reinforcement and reinforcing mechanism of styrene–butadiene rubber by antioxidant-modified silica

Abstract: The focus of this study was on the reinforcement and reinforcing mechanism of the organically modified silica in styrene–butadiene rubber (SBR) It was shown that antioxidant 2-mercaptobenzimidazole (MB) modified silica (silica-s-MB) exhibited better dispersion in SBR than silane-modified silica (m-silica) and the interfacial interaction in SBR/silica-s-MB nanocomposites was stronger than that in SBR/m-silica nanocomposites, leading to a remarkable improvement of mechanical properties for SBR/silica-s-MB nanocomposites compared with those for SBR/m-silica nanocomposites containing equivalent antioxidant component Based on the analysis of the large strain behavior of SBR nanocomposites, the reinforcing mechanisms of silica-s-MB and m-silica were comparatively investigated It was found that the physical entanglements between the crosslinked rubber chains in the immobilized polymer layer and the organic molecules grafted on the silica surface played an important role in the silica reinforcement of rubber, which may be useful for the rational design of filler surface modification

Stress Development of Li-Ion Battery Anode Slurries during the Drying Process

Abstract: The effect of sodium carboxymethyl cellulose (CMC) and styrene butadiene rubber (SBR) on film formation was evaluated by analyzing both drying stress and pore size distribution. We discovered that the SBR in a graphite/SBR slurry filled the voids among the graphite particles with the increase in SBR concentration. In addition, the CMC in the graphite/CMC slurry was adsorbed onto the graphite surface, which caused the graphite particles to coalesce. In the graphite/CMC/SBR slurry, a large amount of SBR was needed to increase the mechanical strength of the film in the low concentration region of CMC. However, in high concentration region of CMC, the SBR did not affect the mechanical strength of the film any longer. On the basis of the drying stress measurements, we could draw a processing window map that clearly shows the effect of CMC and SBR on the mechanical strength of the film, which will be useful in the design of anode slurries.

Innovative neutron shielding materials composed of natural rubber-styrene butadiene rubber blends, boron oxide and iron(III) oxide

Abstract: Optimized flexible and lightweight neutron shielding materials were designed using the Monte Carlo N-Particle (MCNP) code. Thicknesses of 10 mm and 100 mm were tested for neutron shielding performances. Simulation results indicated that the 10 mm shielding material of natural rubber (NR) and styrene butadiene rubber (SBR) blend (1:1) with 60 part per hundred rubber (phr) boron oxide (B2O3) and 100 mm shielding material with four alternating layers of NR with 100 phr iron (III) oxide (Fe2O3) and of NR and SBR blend (1:1) with 10 phr B2O3 were most suitable for thermal neutron shielding and all-energy neutron shielding, respectively. Experimental results verified the shielding efficiency of these optimal designs and ease of fabrication.

Reinforcing styrene butadiene rubber with lignin-novolac epoxy resin networks

Abstract: In this study, lignin-novolac epoxy resin networks were fabricated in the styrene butadiene rubber (SBR) matrix by combination of latex compounding and melt mixing. Firstly, SBR/lignin compounds were co-coagulated by SBR latex and lignin aqueous solution. Then the novolac epoxy resin (F51) was added in the SBR/lignin compounds by melt com- pounding method. F51 was directly cured by lignin via the ring-opening reaction of epoxy groups of F51 and OH groups (or COOH groups) of lignin during the curing process of rubber compounds, as was particularly evident from Fourier trans- form infrared spectroscopy (FTIR) studies and maximum torque of the curing analysis. The existence of lignin-F51 net- works were also detected by scanning electron microscope (SEM) and dynamic mechanical analysis (DMA). The structure of the SBR/lignin/F51 was also characterized by rubber process analyzer (RPA), thermogravimetric analysis (TGA) and determination of crosslinking density. Due to rigid lignin-F51 networks achieved in SBR/lignin/F51 composites, it was found that the hardness, modulus, tear strength, crosslinking density, the temperature of 5 and 10% weight-loss were signif- icantly enhanced with the loading of F51.

Influence of carboxylated styrene–butadiene latex copolymer on Portland cement hydration

Abstract: The influence of carboxylated styrene–butadiene (SB) latex on the hydration of ordinary Portland cement was investigated by means of isothermal heat flow calorimetry, in-situ X-ray diffraction, electroacoustic zeta potential measurement and ion analysis of the cement pore solution. In particular, to assess the influence of the spraying aids polyvinyl alcohol (colloidal stabilizer) and kaolin (anti-caking agent) on cement hydration, the impact of the liquid SB latex was compared with that of its re-dispersible powder. It was found that anionic SB generally retards both the aluminate and silicate reactions. This effect can be ascribed to adsorption of SB particles onto positively charged clinker or hydrate phases and the chelation of calcium ions present in cement pore solution by the carboxylate groups of the SB sample. SB powder exhibits a lower anionic charge density due to PVOH coating, thus interacts less strongly with cement and retards slightly less, compared to liquid SB latex.

Reinforcing mechanisms of carbon nanotubes and high structure carbon black in natural rubber/styrene-butadiene rubber blend prepared by mechanical mixing − effect of bound rubber

Abstract: The reinforcing effect of high structure carbon black (HSCB) and multi-walled carbon nanotubes (MWCNTs) on natural rubber/styrene-butadiene rubber blend processed using mechanical mixing was comparatively investigated. In-depth analysis by dynamic mechanical analysis, the Eggers − Schummer model and Medalia's relationship showed that HSCB aggregates provided large internal pores leading to significant immobilized macromolecules in filled rubber. Additionally, a tubular immobilized rubber layer with a thickness of 8 nm was estimated for the rubber/MWCNT system based on dynamic mechanical analysis data. The mechanical performance of the HSCB filled blend was higher than that of the MWCNT filled blend at the same loading which was correlated to its higher bound rubber content. Both bound rubber content and filler anisotropy were found to govern the overall mechanical properties of rubber/MWCNT composites. Stress softening was correlated with rupture energy suggesting hysteretic failure mechanisms in both MWCNT and HSCB filled rubbers. © 2015 Society of Chemical Industry

Effect of coupling agents and ionic liquid on the properties of rice bran carbon/carboxylated styrene butadiene rubber composites

Abstract: Latex compounding method (LCM) was applied to ensure a better dispersion state of filler in rubber matrix. In order to enhance the compatibility and interfacial interaction between carboxylated-styrene butadiene rubber (XSBR) and rice bran carbon (RBC), a series of coupling agents i.e., N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AAPTS), 3-mercaptopropyltrimethoxysilane (MPTMS), 4,4-methylene bis(phenyl isocyanate) (MDI) and ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate (HMIMPF6) were applied. Morphology of the fracture surface, mechanical property, thermal stability, vulcanization characters and dynamic mechanical property were investigated. The characterization on the resultant composites demonstrated that the MDI exhibited the superior reinforcing effect, of which the tensile strength and 300% modulus reached to 16.43 and 16.33 MPa, respectively. The study on fracture surface, Raman spectrum, thermal stability and storage modulus confirmed the strong interfacial interaction resulted from MDI. In addition, ionic liquid also exhibited coupling activity, improving the mechanical properties of the composites. Open image in new window

Rutting Characteristics of Styrene-Ethylene/Propylene-Styrene Polymer Modified Asphalt

Abstract: Asphalt binder resistance to permanent deformation at intermediate temperature significantly affects overall pavement resistance to rutting. To enhance asphalt resistance to permanent deformation, researchers have used various modifiers and additives such as styrene butadiene styrene (SBS) block copolymer, ethylene vinyl acetate (EVA), polyvinyl acetate (PVA), styrene butadiene rubber (SBR), and natural rubber latex. In this paper, the effectiveness of modification of asphalt binder by styrene-ethylene/propylene-styrene (SEPS) in order to enhance asphalt binder’s resistance to permanent deformation has been investigated using two different evaluation methods: the Superpave specification parameter, G*/sinδ, and the cross model for calculating zero shear viscosity (ZSV). The experiments were conducted using dynamic shear rheometer (DSR) frequency sweep test performed on both the neat sample and modified ones at 40, 50, and 60°C. Utilizing these two approaches, rutting resistance of modified asphalt ...

Bio-inspired polydopamine-coated clay and its thermo-oxidative stabilization mechanism for styrene butadiene rubber

Abstract: Polydopamine (PDA) is labeled as one category of synthetic melanin because it mimics the intriguing radical-scavenging behaviors of its natural counterpart. In this study, PDA modified montmorillonite (PDA-MMT) is utilized as a thermo-oxidative stabilizer for styrene butadiene rubber (SBR). PDA-MMT is fabricated by an aqueous dip-coating, based on the spontaneous alkaline auto-oxidative polymerization of dopamine hydrochloride in an air atmosphere, and is then associated with the SBR matrix via latex compounding. The PDA coating plays an excellent role as a radical-scavenger, and the uniformly dispersed PDA-MMT significantly functions as a physical barrier, which collaboratively work to reduce thermo-induced radical production during the decomposition process of SBR. This mechanism was attested by an in situ thermo-oxidative ageing test along with electron spin resonance (ESR) analysis. Thermal kinetics calculations showing that the apparent activation energy (Ea) of the SBR compounds is augmented by a large margin in the presence of PDA-MMT also corroborate this trend. Above all, the bio-inspired PDA-coating combined with the homogeneous dispersion of MMT exerts a synergistic effect on the thermo-oxidative stabilization of SBR matrix.