Styrene-butadiene Rubber Matrix Research Articles

Poly(styrene)/silica hybrid nanoparticles prepared viaATRP as high-quality fillers in elastomeric composites

Organic–inorganic hybrid nanoparticles of poly(styrene) (PSt) and fumed silica have been successfully synthesized via atom transfer radical polymerization (ATRP) and investigated as fillers for styrene–butadiene rubber (SBR). On the one hand, they were prepared by using the grafting from methodology, in which an ATRP initiator was covalently attached onto the silica and subsequently, PSt chains were grown directly from the surface. On the other hand, the grafting to methodology was used to attach onto the silica, a carboxylic acid end-functionalized PSt, previously synthesized by ATRP. Then, these hybrid nanoparticles could be easily incorporated as fillers into SBR elastomeric matrices by conventional methods employed in rubber technology. The properties of these composites, analyzed by strain sweep tests, scanning electron microscopy, dynamic mechanical measurements, 1H low field double quantum NMR and tensile strength tests, were compared with those obtained using unmodified silica as the filler. The presence of silica particles coated with PSt brushes deeply affects the dynamic and physical response of the elastomer composites prepared, due to the high dispersion and excellent compatibility between the SBR matrix and PSt coated silica. Moreover, the experimental results also indicated that hybrid nanoparticles synthesized by the grafting from methodology are much better for filler applications in the SBR matrix than those obtained by using the grafting to methodology.

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

AbstractHydroxy 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

Styrene-Butadiene Rubber/Halloysite Nanotubes Composites Modified by Epoxidized Natural Rubber

The reinforcement effects of halloysite nanotubes on styrene-butadiene rubber and the modification effect of epoxidized natural rubber on styrene-butadiene rubber/halloysite nanotubes composites were studied. The structure, morphology and properties of styrene-butadiene rubber/halloysite nanotubes composites before and after the incorporation of epoxidized natural rubber were investigated. The results indicated that epoxidized natural rubber can promote the dispersion and orientation of halloysite nanotubes in styrene-butadiene rubber matrix at nanoscale and strengthen interfacial combination between halloysite nanotubes and styrene-butadiene rubber by the formation of covalent bonds and hydrogen bonds between epoxidized natural rubber and halloysite nanotubes. Consequently epoxidized natural rubber can improve the mechanical properties of the vulcanizates of styrene-butadiene rubber/halloysite nanotubes composites. Besides epoxidized natural rubber can decrease the rolling resistance of the vulcanizates and increase the wet grip property of the vulcanizates.

The significance of carbon nanotubes on styrene butadiene rubber (SBR) and SBR modified mortar

A New approach is introduced to incorporate multi-walled carbon nanotubes (MWCNTs) in cementitious materials. The MWCNTs are dispersed in styrene butadiene rubber (SBR) matrix before mixing the matrix with cement. Surfactants have been successfully applied to enhance the dispersion and functionalization of MWCNTs in SBR. The significance of using this MWCNTs–SBR nanocomposite on the mechanical characteristics including compressive and tensile strengths and microstructural features of latex modified mortar (LMM) were examined. Subsequently, the significance of the functionalized MWCNTs on surface chemistry, microstructure and thermal stability of SBR were characterized. MWCNTs were found to be a useful additive for enhancing the mechanical response and thermal stability of SBR. MWCNTs–SBR nanocomposite was observed to be able to bridge micro-cracks in the LMM which helped enhancing its mechanical properties. The ability of MWCNTs to enhance the mechanical response of SBR polymer matrix might be attributed to chemical bond that functionalized MWCNTs can establish with the SBR polymer matrix. The enhanced MWCNTs–SBR nanocomposite gave rise to improved microstructural features of the LMM. Microstructural investigations showed MWCNTs were well dispersed in and bonded to the SBR matrix.

Combined Effect of Nano-Clay and Carbon Black on Mechanical Properties and Aging Resistance of Styrene Butadiene Rubber Nanocomposites

Styrene butadiene rubber (SBR)/clay/carbon black (CB) nanocomposites filled with 60 phr filler (in total) were prepared by adding CB to SBR/clay nanocompound in a two-roll mill. TEM photographs of the nanocomposites showed that both fillers were dispersed randomly in the SBR matrix at nano-scale. With the increase of CB content, stress at 300% strain and tensile strength of the nanocomposites increased, while elongation at break and permanent set of the nanocomposites decreased. On the other hand, with the increase of clay content, the aging resistance of the SBR nanocomposites was improved.

Effect of Functionalized Carbon Nanotubes with Carboxylic Functional Group on the Mechanical and Thermal Properties of Styrene Butadiene Rubber

Multi-walled carbon nanotubes (MWCNTs) were functionalized with a carboxylic functional group to enhance the dispersion of CNT in styrene butadiene rubber (SBR) nanocomposites. The functionalization of the surface of the MWCNTs were carried out by using nitric acid at 120°C for 48 hours. The FTIR technique was used to characterize the surface of the modified carbon nanotubes to ascertain the presence of the functional groups on the CNT surface. The modified carbon nanotubes were incorporated in a polymer solution, and the solvent was subsequently evaporated. Using this technique, nanotubes can be dispersed homogeneously in the SBR matrix in an attempt to increase the mechanical properties of these nanocomposites. The effects of the functionalized CNT on the properties of SBR without curing were studied using characterization techniques such as Differential Scanning Calorimetry (DSC) and the tensile testing machine. The effect of percentage loading of the functionalized CNT was also studied and is reported in this work. The properties of the nanocomposites such as tensile strength, tensile modulus, tear strength, elongation at break and hardness were studied.

Effect of Functionalize Carbon Nanotubes with Amine Functional Group on the Mechanical and Thermal Properties of Styrene Butadiene Rubber

This article reports the investigations carried out on styrene butadiene rubber (SBR) matrices filled with functionalized multi-wall carbon nanotubes (MWNTs). MWNTs were functionalized with amine functional group to enhance its dispersion in SBR nanocomposites. The functionalization of the surface of the carbon nanotubes (CNT) was carried out by using nitric acid at 120°C for 48 h. The FTIR technique was used to characterize the surface of the functionalized CNTs to ascertain the presence of the functional groups on the CNT surface. The modified CNTs were incorporated into a polymer solution and this was followed by subsequent evaporation of the solvent. This technique can be employed to ensure a homogeneous dispersion of nanotubes in the SBR matrix in order to increase the mechanical and thermal properties of the resulting nanocomposites. Results obtained shows significant improvement in the mechanical as well as thermal properties of the nanocomposites. For example the tensile strength increased from 0.16 MPa (blank SBR) to 0.45 MPa (10% CNT) while the young modulus increased from 0.2 MPa (blank SBR) to 0.55 MPa when 10% functionalized CNT was added. Also optimum value of 4.1 KJ energy absorption was obtained with the incorporation of 1% CNT into the SBR matrix. Significant increase in the glass transition temperature was also observed compared to the pure SBR. Thus, CNT functionalized with amine group can be considered as excellent nanofiller for increasing the reinforcing efficiency of SBR.

Research of styrene-butadiene rubber/silicon-aluminum oxides nanotube binary nanocomposites

A novel silicon-aluminum oxides (Si-Al) nanotubes with length ranging from 500 to 1000 nm were introduced to fabricate the styrene-butadiene rubber (SBR)/Si-Al nanotube binary nanocomposites. Scanning electron microscope observation showed the Si-Al nanotubes up to 20 parts per hundred parts of rubber (phr) loading level were dispersed well in SBR matrix. Mechanical properties tests, thermogravimetry analysis and dynamic mechanical thermal analysis revealed that the Si-Al nanotubes have the effects on improving shore A hardness, tensile strength, tear strength, initial decomposition temperature, and storage modulus while lower the maximum loss factor (tan δ) of the SBR/Si-Al nanotube binary nanocomposites. FTIR spectra analysis showed that new SiO bond was generated between the hydroxyl group of Si-Al nanotube and the coupling reagent Si69. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Water-borne graphene-derived conductive SBR prepared by latex heterocoagulation

Water-borne conducting SBR (styrene butadiene rubber) composites containing surface-modified multi-layered graphene sheets (MLGSs) were prepared using a simple heterocoagulation process. Three different types of MLGSs were used and compared; raw, carboxylated, and cetyltrimethyl ammonium bromide (CTAB)-stabilized MLGSs. The SBR latex was mixed with a well-dispersed MLGS aqueous dispersion and heterocoagulated using a flocculant, polyaluminium chloride (PAC), at elevated temperatures. After particle growth and successive stabilization steps, the particulate SBR/MLGS composites were prepared in the size range, 10–100 μm. The CTAB-stabilized MLGSs were dispersed more effectively in the SBR matrix owing to their electrostatic attraction with the negatively charged SBR colloid particles. The MLGS-containing the SBR composites showed improved thermal stability and electrical conductivity. Importantly, the percolation threshold for the electrical conductivity was achieved at a low MLGS concentration, i.e., 0.5 wt%, using this heterocoagulation process.

Influence of Fillers on NR/SBR Blends Containing ENR-Organoclay Nanocomposites: Morphology and Wear

In this study the Epoxidized natural rubber (ENR) and Organoclay (Cloisite 20A) were prepared by solution mixing process. The obtained nanocomposites were incorporated in Natural rubber (NR) and Styrene butadiene rubber (SBR) blends in presence of varying types of carbon black as reinforcing fillers. Morphology, curing characteristics, mechanical and thermal properties were characterized and analyzed. Also, the wear characteristics of the nanocomposites against Du-Pont abrader, DIN abrader and different mining rock surfaces were determined and discussed. The morphology of the organoclay incorporated in ENR shows a highly intercalated structure. ISAF type of carbon black shows a significant effect on curing and mechanical properties by reacting at the interface between SBR and NR matrix. All the samples show only one melting peak at same temperature on the DSC curve. Blends containing ISAF N234 type of carbon black shows high abrasion resistant properties against Du-Pont abrader, DIN abrader and different mining rock. The rubber compound containing 70 wt% of NR, 30 wt% of SBR and 10 wt% of ENR/nanoclay with ISAF N231 are found to be the toughest rubber against all types of rock under the present study.

Design and Preparation of Cross‐Linked Polystyrene Nanoparticles for Elastomer Reinforcement

Cross‐linked polystyrene (PS) particles in a latex form were synthesized by free radical emulsion polymerization. The nano‐PS‐filled elastomer composites were prepared by the energy‐saving latex compounding method. Results showed that the PS particles took a spherical shape in the size of 40–60 nm with a narrow size distribution, and the glass‐transition temperature of the PS nanoparticles increased with the cross‐linking density. The outcomes from the mechanical properties demonstrated that when filled into styrene‐butadiene rubber (SBR), nitrile‐butadiene rubber (NBR), and natural rubber (NR), the cross‐linked PS nano‐particles exhibited excellent reinforcing capabilities in all the three matrices, and the best in the SBR matrix. In comparison with that of the carbon black filled composites, another distinguished advantage of the cross‐linked PS particles filled elastomer composites was found to be light weight in density, which could help to save tremendous amount of energy when put into end products.

DSC study of antioxidant activity of selected p-phenylenediamines in styrene-butadiene rubber

The antioxidant activity of selected N,N′-substituted p-phenylenediamines (PPDs) in styrene-butadiene rubber (SBR) has been studied by differential scanning calorimetry under non-isothermal conditions. The kinetic parameters describing temperature dependence of induction period have been obtained. Protection factors and antioxidant effectiveness have been calculated to characterize the stabilizing effect of the antioxidants under study. It is shown that all antioxidants under study exhibit stabilizing effect on SBR. The obtained values were used to compare the stabilizing effect of the same antioxidants in polyisoprene (PI) rubber. The order of stability for SBR matrix samples differs from that for PI samples. It is shown that the stabilization effect of the antioxidant depends much on the polymer matrix.

Rheological behavior of gel‐filled raw natural rubber and styrene‐butadiene rubber with reference to gel‐matrix intermixing

AbstractNatural rubber (NR) and styrene‐butadiene rubber (SBR) latex gels were prepared by sulfur prevulcanization technique with varying amounts of curing agent and accelerator systems to generate gradient in crosslink density. These gels were characterized by solvent swelling, dynamic light scattering, atomic force microscopy, and mechanical properties. Crosslinked NR gels were intermixed with neat SBR matrix and vice versa. Rheological behavior of chemically crosslinked gel‐filled NR and SBR was studied by capillary rheometry. Intermixing of crosslinked gels in the rubber matrices resulted in a considerable reduction in apparent shear viscosity and die swell values. This behavior was found to be dependent on several factors like gel concentration in the matrix, crosslink density of the gels, their size, and distribution. The effect of temperature on viscosity was studied extensively following the Arrhenious‐Eyring model. A shear rate‐temperature superposition mastercurve was constructed to predict the melt viscosities of the systems as a function of temperature. The change in die swell values was related to the change in first normal stress difference. The scanning electron photomicrographs of the extrudates revealed that presence of gels markedly improved the surface roughness of the raw rubbers. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers

Development of SBR-Nanoclay Composites with Epoxidized Natural Rubber as Compatibilizer

The significant factor that determines the improvement of properties in rubber by the incorporation of nanoclay is its distribution in the rubber matrix. The simple mixing of nonpolar rubber and organically modified nanoclay will not contribute for the good dispersion of nanofiller in the rubbery matrix. Hence a polar rubber like epoxidized natural rubber (ENR) can be used as a compatibilizer in order to obtain a better dispersion of the nanoclay in the matrix polymer. Epoxidized natural rubber and organically modified nanoclay composites (EC) were prepared by solution mixing. The nanoclay employed in this study is Cloisite 20A. The obtained nanocomposites were incorporated in styrene butadiene-rubber (SBR) compounds with sulphur as a curing agent. The morphology observed through X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) shows that the nanoclay is highly intercalated in ENR, and further incorporation of EC in SBR matrix leads to partial exfoliation of the nanoclay. Dynamic mechanical thermal analysis showed an increase in storage modulus and lesser damping characteristics for the compounds containing EC loading in SBR matrix. In addition, these compounds showed improvement in the mechanical properties.

Synergistic effect of carbon black and nanoclay fillers in styrene butadiene rubber matrix: Development of dual structure

Styrene butadiene rubber (SBR) based hybrid nanocomposites containing carbon black (CB) and organo-modified nanoclay (NC) was prepared. X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed the presence of intercalated, aggregated, and partially exfoliated structures. Incorporating 10 phr NC to the control SBR containing 20 phr CB resulted 153% increase in tensile strength, 157% increase in elongation at break and 144% stress improvement at 100% strain, which showed synergistic effect between the fillers. The dynamic modulus reinforcement of nanocomposites was examined by the Guth, Modified Guth, and Halpin–Tsai equations. For predicting CB filled nanocomposite modulus, the contribution of modified intercalated structure of clay and the ‘nano-unit’ (dual structure) comprising CB–NC should be considered.

Nanostructured fly ash–styrene butadiene rubber hybrid nanocomposites

AbstractHybrid nanocomposites of styrene butadiene rubber (SBR) with nanostructured fly‐ash (NFA) were prepared in the laboratory by melt blending technique in an internal mixer. Curatives were added on a laboratory two‐roll mill. Curing characteristics as well as physico‐mechanical properties of the composites were evaluated. A comparison on SBR composites filled with fresh fly‐ash (FFA); carbon black (CB) and precipitated silica (PS) has been reported. In general, SBR‐NFA composites exhibit higher state of cure and higher strength properties as compared with HAF black‐filled and fresh fly‐ash‐filled SBR composites at equivalent loadings. This may be attributed to the higher reinforcing ability of NFA. This fact has also been supported by the swelling studies and Kraus' plot. Tear strength and abrasion resistance of the SBR‐NFA composites were superior to FFA‐filled and precipitated silica‐filled vulcanizates, but were inferior to carbon black‐ filled SBR vulcanizates. The SBR‐NFA composites showed lower hardness as compared with both the carbon black‐filled and silica‐filled composites. Transmission electron microscopy and scanning probe microscopy studies revealed that the NFA particles are well dispersed in the SBR matrix. These results were further supported by fracture surface analysis under the SEM, which revealed the role of NFA in the prevention of fracture propagation. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

Synthesis and Characterization of Styrene-Butadiene Rubber-Clay Nanocomposites with Enhanced Mechanical and Gas Barrier Properties

Abstract Five styrene-butadiene rubber (SBR)/clay nanocomposite or hybrid systems were synthesized via mechanical mixing of SBR using a Brabender mixer and a 2-roll mill in the presence of unmodified sodium montmorillonite (Na-MMT) clay, MMT modified with octadecylamine (C18amine), MMT modified with a zwitterionic surfactant, octadecyldimethyl betaine (C18DMB), and MMT modified with a polymerizable cationic surfactant, vinylbenzyl octadecyldimethyl ammonium chloride (VODAC) or vinylbenzyl dodecyldimethyl ammonium chloride (VDAC). The surfactant chain length and functional groups affected the dispersion of clay nanolayers in the matrix and the overall properties of the nanocomposites. X-ray diffraction (XRD) revealed peaks corresponding to intercalated structures; transmission electron microscopy (TEM) observations agreed well with XRD assessment of the composites. SBR/VODAC-MMT system exhibited the best dispersion among the nanocomposites studied. VODAC-MMT was partially exfoliated in SBR matrix and the average aspect ratio of the nanolayer stacks or aggregates was high (20). Depending on the amount of clay, considerable mechanical reinforcement and gas barrier enhancement were achieved in nanocomposites over pure rubber. Tensile strength in excess of 18MPa was observed in SBR nanocomposites with 30 phr C18 organoclays. The storage modulus at 25C increased by a factor of four by incorporating 10 phr VODAC-MMT in SBR. The most pronounced oxygen barrier enhancement was again observed in SBR/VODAC-MMT nanocomposite with the reduction of permeability by 60% at silicate volume fraction of 0.06. The superior performance of nanocomposites containing VODAC-MMT is attributed to the presence of the vinyl-benzyl group and 18 carbon-atom tail in the surfactant leading to high compatibility with SBR and nano-scale dispersion in the SBR matrix.

Synthesis and Characterization of Chemically Crosslinked Styrene-Butadiene Rubber Nanogels and their Effect on Various Properties of the Rubber

Abstract Nano-sized styrene-butadiene rubber (SBR) latex gels were prepared by pre-vulcanizing SBR latex with different sulfur to accelerator ratios. These gels were characterized by swelling studies, dynamic light scattering, atomic force microscopy, mechanical and dynamic mechanical properties. With the increase in sulfur to accelerator ratio, the gels had higher amount of crosslink density and gel content. Particle size distribution did not alter much in the crosslinked gels. Incorporation of these nanogels into raw SBR led to the considerable drop in viscosity of the gel filled systems under capillary melt flow conditions. However, the reduction in viscosity was found to be dependent on the loading and crosslink density of the nanogels. Energy dispersive X-ray mapping of sulfur was used to check the dispersion of these gels into raw SBR matrix. The die swell values of gel filled SBR were much lower than that of the raw SBR. The reduction in principal normal stress difference values combined with the reinforcement effect of the gels was found to be responsible for the lowering of die swell values. Scanning electron photomicrographs of extrudates of gel filled systems showed much-improved surface smoothness compared to the unfilled SBR. The mechanical and dynamic mechanical properties also showed excellent improvement in modulus with the addition of gels in the raw rubber. A new empirical relationship was proposed to explain the reinforcement properties of nanogels as viscoelastic fillers.

Processing and characterization of functionally graded materials through mechanical properties and glass transition temperature

Functionally graded materials (FGMs) were prepared by construction based layering method through dispersion of carbon nanoparticles in the styrene butadiene rubber matrix. The gradation of material property i.e., ‘glass transition temperature’ was brought in the nanocomposite by varying the concentration of process oil. Glass transition temperature ( T g) of FGMs was varied from − 56 to − 80 °C along the span of 3 mm thick sheet. The gradation of oil in FGMs also changes other properties like tensile strength, elongation at break, modulus, etc. Tensile strength and modulus at 100% drops down while elongation at break continuously increases while moving from one end to other end along the sheet thickness. Thermal analysis of FGMs verifies the compositional changes as well as the change in T g along the thickness.

Carbon nanotubes as reinforcement of styrene–butadiene rubber

This study reports an easy technique to produce cured styrene–butadiene rubber (SBR)/multi-walled carbon nanotubes (MWCNT) composites with a sulphur/accelerator system at 150 °C. Significant improvement in Young's modulus and tensile strength were achieved by incorporating 0.66 wt% of filler without sacrificing SBR elastomer high elongation at break. A comparison with carbon black filled SBR was also made. Field emission scanning electron microscopy was used to investigate dispersion and fracture surfaces. Results indicated that the homogeneous dispersion of MWCNT throughout SBR matrix and strong interfacial adhesion between oxidized MWCNT and the matrix are responsible for the considerable enhancement of mechanical properties of the composite.