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Dynamic mechanical properties of styrene‐butadiene rubber vulcanizate filled with electron beam modified surface‐treated dual‐phase filler
Journal of Applied Polymer Science
Abstract
The influence of the electron beam modification of a dual-phase filler on the dynamic mechanical properties of styrene-butadiene rubber (SBR) is investigated in the presence and absence of trimethylol propane triacrylate or triethoxysilylpropyltetrasulfide. Electron beam modification of the filler results in reduction of the tan δ at 70°C, a parameter for rolling resistance, and an increase in the tan δ at 0°C, a parameter for wet skid resistance of SBR vulcanizates. These modified fillers give significantly better overall performance in comparison with the control dual-phase filler. This variation in properties is explained in terms of filler parameters such as the filler structure that leads to rubber occlusion and filler networking. These results are further corroborated using the master curves obtained by the time–temperature superposition principle. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2992–3004, 2003
... The SBR modeled in this study has a T g of 274 ± 5 K, which is higher than the reported experimental value of 227 K. 72 The higher cooling rate used in simulations compared to experiments causes this apparent disagreement between experimental and simulation glass transition temperature, and it has been reported in previous literature works for linear and cross-linked polymers, ionic liquids, and asphalt. 43,49,61,73 In addition, the transition regime is broader than that in experiments. ...
... 74 In addition, another factor that influences the density value is the lack of cross-linking in the model, which results in a lower density compared to experiments. Using the WLF equation parameters for SBR obtained from experiments (C 1 = 8.5 and C 2 = 163.1 K), 72 it is possible to estimate the shift in the value of T g due to the difference in quenching rates used in simulations and experiments. 73 Following this method, the shift in the T g value is about 120 K. ...
... Universal curves of the (A) storage and loss moduli and (B) phase angle as a function of the rescaled shifted frequency, a T ,s. The universal curves are created at a reference temperature of T 0 = T g,exp = 227 K. (C) Comparison of the horizontal shift factors obtained in experiments and simulations as a function of temperature.72 The experimental SBR sample contained 23.5 wt % styrene and 76.5 wt % butadiene. ...
... Due to the plentiful number of silanols on the silica surface, the polar silica in non-polar rubber matrix and weak rubber-silica interf concurrent obstacles for silica utilization in the rubber industry. Tow many efforts have been made, including silane coupling agents [11 [111], ionizing radiation [112], chemical reactions [113], and macromo zation [114] methods. With the development of ionic liquid-modified ogy, many studies have reported that ILs could improve silica dispe materials and enhance the interfacial bond strength [39,40,95,115]. ...
... Due to the plentiful number of silanols on the silica surface, the poor dispersion of polar silica in non-polar rubber matrix and weak rubber-silica interfacial interaction are concurrent obstacles for silica utilization in the rubber industry. Toward this dilemma, many efforts have been made, including silane coupling agents [110], physical coating [111], ionizing radiation [112], chemical reactions [113], and macromolecular functionalization [114] methods. With the development of ionic liquid-modified nanofiller technology, many studies have reported that ILs could improve silica dispersion within matrix materials and enhance the interfacial bond strength [39,40,95,115]. ...
As a new generation of green media and functional materials, ionic liquids (ILs) have been extensively investigated in scientific and industrial communities, which have found numerous ap-plications in polymeric materials. On the one hand, much of the research has determined that ILs can be applied to modify polymers which use nanofillers such as carbon black, silica, graphene oxide, multi-walled carbon nanotubes, etc., toward the fabrication of high-performance polymer composites. On the other hand, ILs were extensively reported to be utilized to fabricate polymeric materials with improved thermal stability, thermal and electrical conductivity, etc. Despite substantial progress in these areas, summary and discussion of state-of-the-art functionalities and underlying mechanisms of ILs are still inadequate. In this review, a comprehensive introduction of various fillers modified by ILs precedes a systematic summary of the multifunctional applications of ILs in polymeric materials, emphasizing the effect on vulcanization, thermal stability, electrical and thermal conductivity, selective permeability, electromagnetic shielding, piezoresistive sensitivity and electrochemical activity. Overall, this review in this area is intended to provide a fundamental understanding of ILs within a polymer context based on advantages and disadvantages, to help researchers expand ideas on the promising applications of ILs in polymer fabrication with enormous potential.
... When rubber nanocomposite is applied to tire treads, the anti-wet skid performance is generally correlated with the tanδ values at 0 °C [46,47]. The higher the tanδ value at 0 °C is, the better the antiskid performance is. ...
... When rubber nanocomposite is applied to tire treads, the anti-wet skid performance is generally correlated with the tanδ values at 0 • C [46,47]. The higher the tanδ value at 0 • C is, the better the anti-skid performance is. ...
Rubber used in tire is usually strengthened by nanofiller, and the most popular nanofiller for tire tread rubber is nano silica, which can not only strengthen rubber but also lower the tire rolling resistance to reduce fuel consumption. However, silica particles are difficult to disperse in the rubber matrix because of the abundant silicon hydroxyl on their surface. Silane coupling agents are always used to modify silica and improve their dispersion, but a large number of volatile organic compounds (VOCs) are emitted during the manufacturing of the nanosilica/rubber composites because of the condensation reaction between silane coupling agents and silicon hydroxyl on the surface of silica. Those VOCs will do great harm to the environment and the workers’ health. In this work, epoxidized solution polymerized styrene-butadiene rubbers (ESSBR) with different epoxy degrees were prepared and used as macromolecular coupling agents aimed at fully eliminating VOCs. Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) analyses verified that the different ESSBRs were successfully synthesized from solution polymerized styrene-butadiene rubbers (SSBR). With the help of the reaction between epoxy groups and silicon hydroxyl without any VOC emission, nanosilica can be well dispersed in the rubber matrix when SSBR partially replaced by ESSBR which was proved by Payne effect and TEM analysis. Dynamic and static mechanical testing demonstrated that silica/ESSBR/SSBR/BR nanocomposites have better performance and no VOC emission compared with Bis-(γ-triethoxysilylpropyl)-disulfide (TESPD) modified silica/rubber nanocomposites. ESSBR is very hopeful to replace traditional coupling agent TESPD to get high properties silica/rubber nanocomposites with no VOCs emission.
... 9 However, the hydrophilic silica is inclined to agglomerate in nonpolar hydrocarbon rubbers. 9,11 Therefore, silica is generally surface modified through electron beam or plasma 12,13 wrapping with surfactants 14 or grafting with polymer chains or coupling agents 15,16 to improve the compatibility between silica and rubbers. Silane coupling agents provide the most effective strategy to modify silica. ...
... The EDS spectra of the vulcanizates indicate that silica and sulfur are concentrated on the surface of the Si69-containing vulcanizates and the enrichment of sulfur becomes more serious at φ = 0. 12 Figure 8C. It means that [EMIM]OAc could also interact with zinc oxide and improve the dispersity. ...
... tanδ values also serve to evaluate the wet skid resistance and rolling resistance of rubber composites. A higher tanδ (0 • C) indicates better wet skid resistance [38,39], while a higher tanδ (60 • C) reflects greater rolling resistance [40,41]. P0-SBR rubber shows the highest tanδ (0 • C), suggesting that the use of ITPB does not enhance the wet skid resistance. ...
The dispersion of silica in rubber systems and its interaction with rubber are two key factors in the preparation of rubber composites with excellent properties. In view of this, silica modified with terminal isocyanate-based polybutadiene liquid rubber (ITPB) is used to improve the dispersion effect of silica in rubber and enhance its interaction with the rubber matrix to improve the rubber’s performance. The impact of different modification conditions on the dispersion of silica and the properties of modified silica-filled rubber composites were studied by changing the amount of ITPB and the modification method of silica, including blending and chemical grafting. The experimental results show that ITPB is successfully grafted onto silica, and the use of modified silica improves the cross-linking density of rubber, promotes the rate of rubber vulcanization, and overcomes the shortcomings of the delayed vulcanization of silica itself. When the ratio of ITPB liquid rubber to silica equals 1:20, the comprehensive performance of rubber is the best, the ITPB-modified silica has a better dispersion effect in rubber, and the rolling resistance is slightly improved, with tensile strength reaching 12.6 MPa. The material demonstrates excellent overall performance and holds promise for applications in the rail, automotive, and electrical fields.
... Nevertheless, due to the plentiful silanols on silica surface, the poor dispersion of polar silica in nonpolar rubber matrix and weak rubber-silica interfacial interaction are concurrently obstacles for the silica utilization in rubber industry. [11] Toward this dilemma, much of the research has been examined that the surface treatment of silica, such as surfactant adsorption, [12,13] treating silica with electron beam [14] or plasma, [15] and covalently grafting silica with couplings [16][17][18][19] or polymer, [20,21] are practical and effective approach to improve the compatibility between silica and rubbers. One of the most commonly used and convenient method among these ingenious strategies is the surface modification by the condensation reaction of silanol and silane coupling agents. ...
It is usually desired but often challenging to improve the wet traction, and reduce the abrasion and rolling resistance simultaneously in tread rubber, which is referred to as “magic triangle” in tire industry. To fulfill this goal, the filler dispersion and interfacial interaction required to be improved, as they are two essential factors to concurrently govern the ultimate properties of rubber composites. Herein, we synthesized the epoxidized solution polymerized styrene butadiene rubber (ESSBR) with different epoxy level, and used them as interfacial compatibilizer to promote the silica dispersion and silica/rubber interfacial interaction. The epoxy of ESSBR would react with silanol on silica surface and co‐crosslink with SSBR simultaneously, therefore build a strong bridge between rubber matrix and filler. By incorporation of 20 phr of ESSBR‐15% (15% of double bonds on main chain was epoxidized), the wet grip was improved by 40%, and DIN abrasion and rolling resistance were reduced by 38% and 21%, respectively with hardly sacrifice the mechanical properties. We envisage that this study provides an approach for the fabrication of rubber composites with improved silica dispersion and strengthened interfacial interaction.
... Research and development on silica nanoparticles in rubber composites has been substantial. Silica is rst exposed to surface treatments such as passivation by plasma or electron beam [18][19] and physical covering by surfactants or elastomers [20][21][22] in order to minimise surface energy and subsequently improve silica dispersion. Together with the decreased surface energy brought on by surface treatment, the destruction of surface silanol groups, which might act as a reactive site for interfacial reaction, normally takes place. ...
The main inorganic component of rice husk is silica. Washing the rice husk, followed by combustion and chemical treatment, produced high-surface area amorphous extracted nanosilica (NS) and modified extracted nanosilica (mNS). It was established to reinforce a blend of ethylene-propylene-diene monomer (EPDM) and acrylonitrile-butadiene rubber (NBR) using different amounts of mNS, specifically 2, 4, 6, 8, and 10 phr. The cure properties, mechanical, physical, and swelling resistance examinations of the sulphur-cured nanocomposites were studied. The results showed that while the torques were prolonged with increasing mNS concentration, the optimum cure time (t 90 ) and scorch time (t s2 ) decreased. The homogeneous distribution of nanosilica particles throughout the rubber matrices was confirmed by the FESEM micrographs. The outcomes guaranteed a discernible improvement in the nanocomposites' examined qualities.
... The wet skid resistance of rubber is a very important factor which seriously affects the mechanical performance of O-Rings and Belts. The higher loss factor at 0 °C indicates the better wet skid resistance 57 . As shown in the Fig. 13b, the samples contained grafted nano silica illustrated the highest tanδ at 0 °C. ...
Non-agglomeration and dispersion of silica nanoparticles in polymers and their interfacial interactions to polymer matrix are the most important factors that influence nanocomposites performance. In this work, vinyltriethoxysilane (VTES) as a low VOC emission coupling agent was used for surface modification of silica nanoparticles to prepare better dispersion in nitrile rubber (NBR) and improve its interfacial interactions to silica nanoparticles. The results of X-ray photoelectron spectroscopy, thermogravimetric analysis and Fourier transform infra-red spectroscopy demonstrated successful attachment of VTES molecules on the surface of silica nanoparticles. Dispersion of the modified silica nanoparticles in NBR matrix was studied using field emission scanning electron microscopy and rubber process analysis. Results demonstrated that VTES significantly improved dispersion of nanoparticles in rubbery matrix. The bound rubber content showed that VTES effectively built a bridge between the silica nanoparticles and the rubber matrix that led to promising mechanical performances and strong interfacial interactions. Effect of nanoparticle content on the mechanical performances (static/dynamic) of the NBR was evaluated. It was found that higher modulus and reinforcement indices was obtained at 3 and 5 wt% of nanoparticles. Moreover, these composites had extremely low rolling resistance, the best wet skid resistance and the lowest Heat-Build up.
... The peak temperature of the loss factor is closely related to the glass transition temperature of the rubber matrix. 44,45 From Figure 9(b), the glass transition temperature of NR composite is about À50 C, but with the increase of ENR/NR ratio, the second peak appears in the curve at about 0 C, which is related to the glass transition temperature of ENR, indicating that phase separation occurs inside the composite. Tanδ at 0 C usually represents the tire anti-wet skid performance and Tanδ at 60 C represents the rolling resistance. ...
Tire development tendency is green, environment‐friendly, and safeguarding life and health. The conventional tires, consisting of solution polymerized styrene‐butadiene rubbers (SSBR), silica, silane coupling agents, and other rubber additives, will not be able to keep up with the demand. SSBR, as a synthetic rubber processed from nonrenewable petroleum resources, creates a large amount of carbon emissions in the production process and the reaction between silica and silane coupling agents generates a large amount of volatile organic compounds (VOCs), which is detrimental to the environment and human health. In this article, epoxidized natural rubber (ENR) with different epoxide degrees was successfully prepared and blended with natural rubber (NR)/silica composites to improve the dispersion of silica and the performance of nanocomposites. The effect of heat treatment temperature on the reaction between ENR and silica and the dynamic and static mechanical properties of ENR/NR/silica nanocomposites was investigated by mechanical properties test, transmission electron microscopy, x‐ray photoelectron spectroscopy, and Fourier transform infrared. The results showed that the epoxy groups on the ENR molecular chain could react with the silanol on the surface of silica to form a strong chemical bond, which improved the dispersion of silica in the rubber matrix and further enhanced the performance of the rubber composites without carbon emission and VOCs.
... Because of poor compatibility between silica and hydrocarbon rubber (11)(12)(13), a great effort has been made to improve the filler-rubber interaction with the aim of obtaining optimum performances (14)(15)(16)(17)(18)(19)(20)(21). Three main directions have been developed to enhance the interaction between filler and rubber, i.e., addition of coupling agent (22)(23)(24)(25)(26)(27)(28)(29), surface modification of filler (30)(31)(32)(33)(34)(35)(36)(37)(38)(39), and chemical modification of rubber (40,41). ...
Silica and carbon black (CB) co-filled rubber composite was widely used for tire tread and other rubber products because of combined advantages of binary fillers, such as low hysteresis, good abrasion resistance, and reinforcement. Numerous studies have been focused on the filler–rubber interaction with the aim of obtaining optimum performances. To investigate the effect of modification on properties of rubber composite, modified silica and CB co-filled rubber composite was prepared with a multi-functional silane coupling agent, 2-aminoethyl-2-(3-triethoxysilylpropyl)aminoethyl disulfide (ATD). Such modification significantly enhanced the filler–rubber interaction and improved the filler dispersion. For the modified composites, the state of cure, hardness, tensile strength before and after aging, stress at 300% elongation, tear strength, abrasion resistance, rebound resilience, compression set, temperature rise, and the value of dynamic loss coefficient ranging from −20°C to 80°C were significantly improved, especially with low ATD dosage (3.0 phr). This modification provides an effective route to prepare silica and CB co-filled rubber composites with improved mechanical properties and dynamic mechanical properties.
... This phenomenon is called the Payne effect. A Payne effect factor ( PE) defined in Eq. (6) was introduced to quantify this effect [30,31] Table 5, greater rotor speed and longer compounding time produce smaller Payne effect factor. This depicts a lesser interaction between fillers. ...
This study analyzes the effects of rotor speed, mixing time, and initial temperature on the curing characteristic, mechanical and dynamical properties, as well as the morphology of nanostructured silica/natural rubber composites. The rotor speed, mixing time, and initial temperature settings of the mixer were adjusted in the range of 40–100 rpm, 15–24 min, and 80–100 °C, respectively. Furthermore, a combination of good dispersion with a moderate mastication effect was used to obtain the vulcanizate's good mechanical properties and prevent premature crosslinking. The result showed that at a rotor speed of 60 rpm, excessive rubber degradation occurred at the compounding time of more than 21 min, while at the compounding time of 24 min, it occurred at rotor speeds of more than 40 rpm. Meanwhile, premature crosslinking occurred at an initial mixing temperature of 100 °C, with a velocity gradient in the range of 8.2–11.3 s−1 providing excellent reinforcement of natural rubber composite by nanostructured silica from bagasse ash.
... Silica nanoparticles with high surface energy and multiple silanol groups on their surface are hard to disperse homogeneously but tend to agglomerate in rubber matrices [8,21,22]. To improve the dispersity, silica is often modified via surfactant wrapping, electron beam or plasma treatments [23,24], polymer grafting and coupling agent modification [25,26]. Among many silane coupling agents bis(γ-triethoxysilylpropyl)-tetrasulfide (Si69) is one of the most commonly used one to promote the silica dispersion [27,28]. ...
In this paper we designed greener rubber nanocomposites exhibiting high crosslinking density, and excellent mechanical and thermal properties, with a potential application in technical fields including high-strength and heat-resistance products. Herein 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc) ionic liquid was combined with silane coupling agent to formulate the nanocomposites. The impact of [EMIM]OAc on silica dispersion in a nitrile rubber (NBR) matrix was investigated by a transmission electron microscope and scanning electron microscopy. The combined use of the ionic liquid and silane in an NBR/silica system facilitates the homogeneous dispersion of the silica volume fraction (φ) from 0.041 to 0.177 and enhances crosslinking density of the matrix up to three-fold in comparison with neat NBR, and also it is beneficial for solving the risks of alcohol emission and ignition during the rubber manufacturing. The introduction of ionic liquid greatly improves the mechanical strength (9.7 MPa) with respect to neat NBR vulcanizate, especially at high temperatures e.g., 100 °C. Furthermore, it impacts on rheological behaviors of the nanocomposites and tends to reduce energy dissipation for the vulcanizates under large amplitude dynamic shear deformation.
... 12 Beside these methods, electron beam or plasma treatment also can improve hydrophobic or hydrophilic nature of silica. 16,17 But the aggregation caused by large specific surface area of silica and strong interparticle interaction is still not eliminated completely. In recent years, surface modification of silica and the development of new highly dispersed silica have also been subjects of interest. ...
The dispersion of filler and interfacial interaction are crucial in determining the properties of rubber composites. Aiming to improve the dispersion and filler–rubber interaction, we introduce rubber graft bearing oniums in a rubber/silica composite. To fulfill this goal, the graft, which is prepared via thio‐ene click reaction between 1‐methylimidazolium mercaptopropionate (MMP) and the pendent vinyl groups of a solution‐polymerized styrene‐butadiene rubber (SSBR), is introduced into the silica‐filled styrene‐butadiene rubber (SBR) composite. The dispersion of silica and interfacial interaction are improved via hydrogen bonding interaction. Moreover, the graft exhibits catalytic effect toward the silanization, which can improve interfacial interaction in the composites with bis [3‐(triethoxysilyl) propyl] tetrasulfide. With 2 phr of the graft, the tensile modulus (stress at 300% strain) is increased by 18% and the abrasion loss is decreased by 31%. This study opens a new attempt to improve the filler dispersion and filler–rubber interaction in the composites with onium‐bearing polymers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48243.
... Similar findings have been reported previously by Shanmugharaj and Bhowmick. 48 It was stated that changes in T g are mainly attributed to trapped or occluded rubber. ...
In the present study, chloroprene rubber waste (CRW) was used in an attempt to extend its use and create a value-added material based on natural rubber (NR) and CRW blends. Conventional fillers including carbon black (CB), silica (SS) and calcium carbonate (CC) were used individually to optimize the performance of the rubber blends. The properties evaluated were the curing characteristics, physical and dynamic properties and thermal stability. From the results obtained, it is clear that the type and amount of filler play a crucial role in promoting the performance of the blend. A faster curing rate was observed for the blends containing CB and CC, while SS-filled NR/CRW blends showed the opposite trend. SS-filled NR/CRW blends exhibited tremendously improved tensile properties compared with CB- and CC-filled blends. This is because two types of competing interactions/reactions take place: the dipole–dipole interaction between SS and CRW and the silane coupling reactions. The tensile properties are also in good agreement with the observed dynamic properties. A higher storage modulus and a lower damping factor were found in the blends containing CB and SS, indicating more restricted molecular mobility caused by rubber–filler interactions.
... [16][17][18] Nonetheless, these CSDPFloaded elastomer composites do not exhibit betterment in the desired properties when compared to the CB-loaded systems, though it showed a relatively good performance in comparison to the silica-filled elastomeric composites. [19][20][21] Alternatively, few CB industries adopted surface coating technology, where the carbon particles are being coated with silica shell. 22 Although it showed a relatively good performance in tire formulations, the variation in the rolling resistance properties is not quite significant in comparison to the silica-filled rubber composites. ...
Silica–graphite filler was prepared via two-step grafting procedure by grafting silica particles onto the expanded graphite. In the first step, isocyanatopropyltriethoxysilane was chemically introduced onto the silica aggregates, which was followed by grafting onto the expanded graphite via urethane linkage in the second step. Successful grafting of silica aggregates onto the graphite was corroborated using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The presence of a thin graphene layer on silica aggregates corroborated using transmission electron microscopy confirmed the grafting of silica aggregates onto the graphite surface. Styrene–butadiene rubber (SBR) composites with various silica–graphite loadings were prepared by melt processing technique to generate pristine silica and silica–graphite-filled elastomeric composites. Rheometric cure studies revealed that the torque difference (ΔS) increased with pristine silica loading, when compared to the unfilled SBR system, and this effect is more pronounced on loading silica–graphite filler. Improvements in mechanical properties such as modulus and tensile strength were observed with increasing loading of silica particles and this effect is more pronounced on loading silica–graphite fillers, indicating that this is due to the rise in the elastomer–filler interactions in the silica–graphite-loaded SBR systems. This fact was further corroborated using bound rubber content and equilibrium swelling ratios of the unvulcanized and vulcanized SBR composites.
... The tests were carried out employing three different rubber compounds, C1, C2, and C3, provided by a pneumatic tire manufacturing company, interfaced with the three cited different materials: glass, marble, and 3M tape. Preliminarily all compounds were characterized by means of dynamic mechanical analysis and differential scanning calorimetry [24] [25] tests carried out at 1 Hz frequency (Figs. 6 and 7). Glass and marble were scanned by means of a profilometer, while 3M surface was analyzed by means of a laser scan (Fig. 8), whose degree of resolution allows the evaluation of the only macroscopicroughness parameters (the microscopic ones will be obtained by means of the cited self-affine fractality principle [16]). ...
The results of an experimental activity, carried out using a prototype of pin on disk machine and aimed at investigating the frictional behavior of visco-elastic materials in sliding contact with rigid asperities, are presented.
The pin is a rubber specimen coming from three different passenger automotive tires, while the disk is covered with glass, marble, or 3M anti-slip tape surfaces. Tests, performed both in dry and wet conditions, highlighted that the friction coefficient is strongly influenced by the effect that surface roughness plays on friction mechanisms of adhesion and hysteresis. The results confirmed the theoretical dependence of friction on vertical load, sliding velocity, rubber characteristics, and track conditions.
... To maximize the potentials of silica in rubber composites, especially in tires, great efforts are focused on the surface treatments of silica to enhance the compatibility between silica and rubbers. Various strategies including physically wrapping silica with a surfactant 4 or polar rubbers as compatibilizers, 5 treating silica by electron beam 6 or plasma, 7 and covalently grafting silica with a coupling agent 8−10 or polymer chain 11 are explored to tailor the surface properties of silica. Among them, the most convenient method for surface functionalization is to utilize the condensation reaction between the silanol groups on the silica surface and suitable silane coupling agents. ...
In silica-filled rubber composites, the silanization modification of silica plays a vital role in enhancing the compatibility between silica and a rubber matrix and hence the properties of the composites. In the present study, with the goal of promoting silanization reactivity and extent, we utilize a phosphonium ionic liquid (PIL) as a novel catalyst for the silanization reaction between silica and bis(3-triethoxysilylpropyl)-tetrasulfide (TESPT), a commonly used silane in the tire industry, in the styrene-butadiene rubber (SBR) matrix. Dynamic rheological measurement, bound rubber measurement, freezing point depression, and heat capacity increment together show that the addition of a small amount of PIL into a TESPT-modified SBR/silica composite gives rise to significant improvement in the interfacial adhesion between silica and the rubber matrix, which is on account of the promoted silanization extent of silica with the catalyst of PIL. Consequently, the resulting composite prepared at room temperature with fewer parts of TESPT exhibits superior overall performance in comparison with the composites prepared by adding excessive TESPT and compounding at an elevated temperature. In particular, the energy loss during rolling of the rubber wheel is drastically decreased as a result of the improved interfacial silanization, which shows great potential in energy-saving green tires.
... The results of the characterization are shown in Fig. 5 (E') and in Fig. 6 (tan(δ)), highlighting a clear glassy transition zone and the expected trends respect to temperature [7]. Moreover, with the aim to identify properly the glassy transition temperature, the specimen has been object of analysis performed with Differential Scanning Calorimetry (DSC) technique [8]. ...
The results of an experimental activity carried out with the aim to investigate on the adhesive behaviour of visco-elastic materials in sliding contact with road asperities are presented. Experiments are carried out using a prototype of pin on disk machine in which pin is constituted by a specimen of rubber coming from a commercial tire, while different disks are realized in glass, marble, steel and in abrasive paper of different roughness. Tests are performed in both dry and wet conditions. Roughness of the test surfaces is evaluated by a rugosimeter, while pressure is evaluated, off-line, analysing the extension of the contact patch left by the pin on a sheet of graph paper under known applied loads. Slide velocity is imposed by an inverter controlled motor driving the disk. Basing on well known theoretical hypotheses, adhesive component of friction coefficient is estimated making the specimens slide on surfaces characterized by low values of macro-roughness, in order to underline the differences in rubber behaviour respect to micro-roughness surface variations. The results confirmed adhesion dependence on pressure and sliding velocity in both cases of smooth surfaces, where the main friction mechanism is the adhesive one, and of rough surfaces, where the main friction mechanism is the hysteretic one. Analysing various surfaces roughness it is possible to notice a maximized adhesive contribution on flat surfaces; it reduces with increasing roughness, while hysteretic friction comes over instead of it because of asperities penetration into rubber sliding surface. Moreover in the case of rough surfaces the separation between static and dynamic friction coefficient is evident and the static coefficient is greater than the dynamic one. On the other hand in case of smooth surface the absence of indentation phenomena doesn't allow to recognize, in the measured force time history, the "classical" peak usually associated to the static friction coefficient. Dry and wet tests performed on different micro-roughness profiles highlighted that friction coefficient in dry conditions is greater on smoother surfaces, while an opposite tendency is shown in wet condition, when asperities are greater enough to break the thin water layer, providing a certain degree of indentation. A proposal for a methodology able to estimate the only adhesive friction component, developed thanks to wet contact tests, is expressed in the end of the paper.
... And the PCL based elastomer had higher tanδ value than the PTMG based elastomer at the temperature around zero centidegree. Based on the time-temperature superposition principle, a conclusion can be made that the PCL based elastomer exhibits good wet skid resistance, low rolling resistance and outstanding dynamic application properties[45,46,47]. In a word, The PCL based elastomer possesses more balanced properties. ...
A series of three cast polyurethane elastomers were prepared from 2,4-toluene diisocyanate (TDI) and 3,5-dimethyl-thioltoluenediamine (D MTDA) chain extender, with polyethylene adi-pate (PEA), polyoxytetramethylene glycol (PTMG) and polycaprolactone (PCL) soft seg-ments. The polyol molecular weights em-ployed was 2000g/mol. The polyurethane elastomers were characterized by an elec-tronmechanical universal testing machine, an Akron abrasion loss tester, a LX-A Shore du-rometer, a rebound resilience equipment and a Dynamic- Mechanical analyzer. In addition, fractured surface of the polyurethane elas-tomers was investigated by a field emission scanning electron microscopy (SEM). The test results showed the PCL based elastomer ex-hibits the excellent tear and stress-strain properties that polyester based elastomers offer, while retaining superior compression set and resilience similar to polyether based elas-tomers. The static and dynamic properties of the PCL based elastomer were more suitable for dynamic applications. The SEM micro-graphs of all polyurethane samples indicated the existing of the microphase separation structure. Particles of the dispersed phase formed by the hard phase and crystalline part of the soft phase grows bigger with the in-creasing crystallinity of the soft segments. The hard domains are irregular shapes and with the sizes of a few micrometers.
... Earlier workers have reported the properties of CB filled rubber vulcanizates. It has been amply demonstrated that the structure, particle size, and functional groups on the surface influence the critical performance properties [2][3][4][5]. Jia et al. [6] reported a very high reinforcement and stiffening effect of NC in nano-CB filled rubber composites having 10, 20, 30 phr of total filler loading. Combined effect of NC and nano-CB on properties of natural rubber (NR) nanocomposites was evaluated. ...
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.
... [13][14][15][16][17] For example, Inoubli et al. 14 investigated polybutylacrylate (PBA) filled with Stöber silica particles grafted with PBA chains; their small-angle neutron scattering and transmission electron microscopy results showed well-dispersed grafted silica particles in the PBA matrix. Other methods such as thermal treatment 18 and plasma surface modification of silica [19][20][21] were also reported to be effective in tuning the structure and performance of the rubber compounds. ...
Sorbic acid (SA) was used to improve the performance of styrene–butadiene rubber (SBR)/silica composites by direct blending. The mechanisms for the significantly improved performance were studied by X-ray photoelectron spectroscopy, X-ray diffraction and by the determinations of bound rubber content and crosslink density. The strong interfacial bonding between silica and the rubber matrix resulted from SA-intermediated linkages. Significantly improved dispersion of silica by virtue of the interactions between silica and SA was found. Formation of zinc disorbate during compounding of composites was confirmed. The effects of SA content on vulcanization behavior, morphology, mechanical properties and abrasion loss of composites were studied. Significantly improved mechanical properties of SA-modified SBR/silica composites were demonstrated. Changes in vulcanization behavior, morphology and performance were correlated with the interactions between silica and SA and the largely improved dispersion of silica.
This work aimed to develop compatible blend between natural rubber (NR) and ethylene propylene diene rubber waste (w-EPDM). This was done by introducing third rubber matrix and electron-beam (EB) irradiation. As for the first method, natural rubber latex (NRL) was added where it was mixed with w-EPDM prior to blend with NRL on a two-roll mill. However, the latter route was prepared differently, EB-exposed to the samples in the presence of trimethylolpropane triacrylate (TMPTA) as cross-linking promoter. By applying these two methods, the compatible blends of NR and w-EPDM were successfully prepared. The blends exhibited good cure properties, solvent resistance, tensile, and dynamic mechanical properties. NR and w-EPDM were more entangled after introducing these two methods.
Electron beam radiation (EBR) technology is one of the most promising technologies among other radiation-driven technologies and has been used in the rubber and tyre industry due to its ability to cross-link certain rubbers depending on their chemical structures. EBR can provide good green strength to rubber and rubber products by partial cross-linking which has practical importance in the radial tyre building process. The tyre components where EBR has practical application include tyre treads, inner liners, belt, and body ply skim compounds. This book chapter discusses the effect of EBR on the structure and properties of tyre rubbers, such as natural rubber (NR), styrene-butadiene rubber (SBR), polybutadiene rubber (BR), synthetic polyisoprene (IR), and isobutylene-isoprene rubber or butyl rubber (IIR). The impact of EBR on the performance triangle properties of the tyre such as rolling resistance, wet grip, and abrasion resistance are discussed in detail. The viability of the application of this process in the modern-day tyre industry is also highlighted.
The nonlinear viscoelastic behavior of rubber composites is of great practical importance in their processing as well as the application. In this paper, nonlinear viscoelastic behavior for vulcanized and unvulcanized filled styrene butadiene rubbers (SBR), SBR/carbon black (CB) composites, were mainly investigated. Besides the conventional Payne effect, frequency (ω) sweep tests at different strains (linear and nonlinear viscoelastic regions) were performed to get more information about viscoelastic response, especially in nonlinear region that close to actual driving conditions. Conductivity synchronization test was also operated to explore the evolution of CB agglomerates. It reveals that the filler network structure recovers slowly but the rubber network recovers rapidly during an increasing and decreasing strain sweep cycle. At large strain, rheological parameters of vulcanizates change significantly with increasing ω. A pseudomaster curve based on the ω sweep at large strain and different temperature can be obtained both for compounds and vulcanizates, indicating that the time-temperature superposition is also applicable to the nonlinear viscoelastic behavior. Similar linear and nonlinear viscoelastic behaviors of filled vulcanizates to that of unfilled vulcanizates demonstrate the same mechanism of viscoelastic response. The loss modulus peak of filled vulcanizates primarily comes from the Rouse movement of rubber chains between crosslinking points. Under large strain, the strain amplication effect of particles hardly influence the characteristic relaxation time of Rouse movement between crosslinking points.
In the tread compound of Green tire, silica dispersity is critical for obtaining high‐performance rubber composites. Ionic liquids have been successfully applied in improving the dispersity of silica through chemical and physical interaction. However, recent research has found that ionic liquids are harmful to the ecological environment. Meanwhile, the price of them is high. In this paper, the deep eutectic solvents (DESs‐Choline Chloride: urea) was synthesized successfully. Then it was directly introduced to prepare silica‐filled styrene‐butadiene rubber (SBR) compound via an in‐situ method. The carbonyl group and amino in DESs could constitute a hydrogen bond with the silanol on the silica surface. The hydroxyl groups were able to react with the silanol groups. The amino groups in DESs could treat as a secondary facilitator, which accelerated the curing rate. The results showed that DESs improved the dispersity of silica effectively and strengthened the interaction between silica and SBR chains. Particularly, the comprehensive performance of the rubber vulcanizates improved with an optimal ratio of bis(3‐triethoxysilypropyl)‐tetrasulfide (TESPT) to DESs being of 1:1. In addition, the DESs will serve as a novel material in silica‐filled SBR composites, which will expand its application in the tire industry.
Bis-(γ-triethoxysilylpropyl)-tetrasulfide TESPT (Si69) is the most popular silane coupling agent for green tires. However, a large amount of alcohol vapours (a kind of volatile organic compounds (VOCs)) release when it is used for tire production, which can make the process harmful to tire quality and people’s health. In this work, Mx-Si69 (x = 1, 2, 3, 4, 5, 6), a series of silane coupling agents were successfully synthesized by transesterification of fatty alcohol polyoxyethylene ether-9 (AEO-9) with Si69. A series of Si69 molecule grafted with one to six fatty alcohol polyoxyethylene ether chains (the long alkoxy chain) (named as M1-Si69 to M6-Si69) were produced.The FT-IR and ¹H-NMR results revealed that six coupling agents named M1-Si69∼M6-Si69 could be obtained by adjusting the molar ratio of the reactive monomers. So, the VOCs emission could be reduced by 37.5%∼100% theoretically because of the long chain reaction products. The FT-IR and TGA results demonstrated that Mx-Si69 could successfully modify silica. Then, silica/rubber compounds were prepared by adding these low VOCs coupling agents namely M1-Si69∼M6-Si69. The dynamic and static mechanical results indicated that silica/rubber compound made by adding M2-Si69 had the lowest Heat-Build up, the best wet skid resistance, and extremely low rolling resistance (it can save more than 20% energy consumption than Si69).
Silanized plasticizer (SP) was chemically derived and synthesized from soybean oil (SBO) co-vulcanized with bis-(3-(triethoxysilyl)-propyl) tetrasulfide (TESPT) by using the sulfur-accelerated curing system. SP extended styrene-butadiene rubber (SBR)/silica composites have been studied for their improved filler dispersion through coupling interaction at the SBR/silica interface. The effect of SP on cross-link density, thermal, static and dynamic mechanical properties of SBR composites related to the tire performance, were investigated. The results revealed that SP enhanced tensile strength, modulus, and hardness of the composites due to an improved matrix-filler interaction together with an excellent control over oil migration. Further improvement was observed for SP with increasing TESPT content, what was related to the increase in cross-linking density, and bound rubber content of the composite materials. Morphology and reduced Payne effect confirmed the silica particles have an even dispersion throughout the SBR matrix. The dynamic curves indicated the highest efficacy for wet and dry traction performances of SP extended SBR composites comparing to unmodified reference sample. This research provided the effect of SP as a novel reactive bio-plasticizer to improve the performance of SBR/silica composites for green tire manufacture, while being eco-friendly.
Silica has been established as one of the most promising materials in green tires. The filler–rubber interactions can increase the comprehensive performance of rubber composites. In this study, sodium silicate was used as the silicon source and hexamethyl disilazane (HMDS; molecular formula: C6H19NSi2) was used as a modifier to synthesize dispersible silica (DNS) via an in situ surface‐modification method. The effects of the HMDS‐capped silica on the properties of rubber–matrix composites made of styrene–butadiene rubber (SBR) and high‐cis‐polybutadiene rubber (BR9000 or BR) were investigated with Zeosil 1165MP (Z1165‐MP; a commercial highly dispersible silica produced by Rhodia for the production of green tires in the rubber industry) as a reference. The results show that the SBR–BR–DNS composite was before the SBR–BR–Z1165‐MP composite in increasing the tear strength and elongation at break and reducing the compression heat buildup. On the basis of the resulting properties, the reinforcing behaviors in the rubber–matrix composites were analyzed. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47763.
Surface modification of fillers has a profound influence on the dispersion of filler and interfacial adhesion, and thus the final performance of polymer-based composites. In this contribution, the modification of silica by polymethylhydrosiloxane (PMHS) is conducted via an efficient and fast tris(pentafluorophenyl)borane-catalyzed functionalization, which can be completed within a few minutes at room temperature. A highly hydrophobic surface and an uncompromised reactivity are concurrently observed in the modified silica. By comparison between the composites filled with pristine and modified silica, it is revealed that such PMHS modification can not only improve the dispersibility of silica by lowering the surface energy, but also enhance the interfacial interaction in virtue of the reactivity of the residual Si–H bonds. With a PMHS grafting content as low as 1.5 wt%, the modified composite exhibits tremendous improvements in mechanical properties (116% increase in modulus) and dynamic performances (116% increase in wet traction and 26% reduction in rolling resistance). Considering the superior overall performance of the modified composites, together with the simplicity and rapidity of the modification process, we envision that the hydrosilane-modified silica has great potential in the fabrication of high-performance polymer composites such as energy-saving tire treads.
The reutilize of rubber waste in the virgin rubber blends is arise as a solution for disposal problem. However, the disadvantage of the rubber waste addition is deteriorates the properties of the rubber blends. In this work, the effect of electron beam irradiation on different states of the natural rubber/recycled chloroprene rubber blends; uncured and cured states were investigated. Various rubber blends ratios were prepared using two-roll mill and then constant irradiated doses was used at 20kGy. From the result obtained, the tensile strength of the pre-cured rubber blends was higher than that post-cured. Similar observation can be obtained in the elongation at break and swelling percentage. The tensile modulus and crosslink density in post-cured blends are higher. The crosslink density calculation from swelling measurement supports the observations in the mechanical properties.
Most rubber materials are subjected to oxidation. The rate of oxidation depends on the type of rubber, processing method, and end-use conditions. The oxidation of rubber can result in the loss of physical properties, such as tensile strength, elongation, and flexibility. Hence, the service life is determined by oxidation stability. Thermal properties are relevant to the potential use of polymeric materials in many consumer oriented applications. Thermo-oxidative ageing and thermogravimetric analysis (TGA) have been proven to be successful techniques in determining the thermal stability of polymers and polymer blends. In this article, preparation of a series of natural rubber/recycled ethylene-propylene-diene rubber (NR/R-EPDM) blends is described. Processing of the blends, by means of introducing pre-vulcanised EPDM and electron beam (EB) irradiation, was carried out. Two thermal analysis methods, namely thermo-oxidative ageing and thermogravimetric analysis, were conducted. The results indicated that pre-vulcanising EPDM for 1.45min (ts - 2) is sufficient to gain the optimum retained tensile and elongation at break. It was simultaneously observed that the introduction of pre-vulcanised EPDM increased decomposition temperature and activation energy by showing optimum values at a pre-vulcanising time of 3.45 min (ts). In the latter study, the retained properties increased after EB irradiation. The results can be verified by the thermal decomposition temperature and their activation energy. The obtained TG profiles and the calculated kinetic parameters indicated that introducing EB irradiation into the blends enhanced their thermal stability. The thermal stability of the blends, processed by these two means, is significantly enhanced; irrespective of pre-vulcanising time or irradiation dose.
Nanocomposites based on Styrene Butadiene Rubber (SBR) and Acrylonitrile Butadiene Rubber (NBR) with varying acrylonitrile contents (19%, 34% and 50%, respectively) and octadecyl amine modified and unmodified Na-Montmorillonite clays were prepared. Dynamic mechanical thermal analysis (DMTA) was performed on these composites over a range of temperatures (-80 °C to +80 °C), frequencies (0.032 Hz to 32 Hz) and strains (0.001% to 10%). The results showed that there were significant changes in tan delta peak temperature and height and storage modulus with the addition of small amount (4 phr) of the modified and the unmodified fillers. These were magnified with the increase of filler loading. The tan delta peak heights decreased and the storage modulus increased in general. With increasing strain, the nanocomposites showed lowering of storage modulus, because of the breakdown of the agglomerated structures. The storage modulus increased with increasing frequency, and the modified filler loaded samples registered higher E' values compared to those of the gum rubber.
Mechanical and dynamic mechanical properties of natural rubber/recycled ethylene-propylene-diene rubber (NR/R-EPDM) blends were simultanoeusly enhanced by electron beam (EB) irradiation. The cross-linking promoter, trimethylolpropane triacrylate (TMPTA), was also introduced into the blends to induce the cross-linking. By applying EB irradiation, the tensile modulus, hardness, swelling, cross-link density, and storage modulus increased with increase in the irradiation dose; an irradiation dose of 50 kGy was efficient to gain optimum tensile strength. The formation of irradiation-induced cross-links after EB irradiation is a major concern for the enhancement of mechanical, swelling resistance, and dynamic mechanical properties of the blends.
This article deals with blends based on natural rubber (NR) and recycled ethylene-propylene-diene rubber (R-EPDM). Natural rubber latex (NRL) was introduced into the blends to enhance interfacial adhesion between NR and R-EPDM. A new route of compounding was also suggested. The blends were prepared by mixing R-EPDM and other additives in NRL before blending with natural rubber on a two-roll mill. By applying this method, the homogeneity of the blends and cross-linking distribution are significantly improved. The blends exhibited superior state of cure, swelling resistance, mechanical properties and dynamic mechanical properties. The degree of entanglement between NR and R-EPDM also increased after NRL modification.
The tribological properties of acrylonitrile-butadiene rubber (NBR) filled with two kinds of carbon black filler were examined. Different types of Semi-Reinforcing Furnace (SRF), and High Abrasion Furnace (HAF) blacks were used as filler material to test the influence of carbon black particle size on the friction and wear of NBR. Results from tribological tests using a ball on disk method showed that the smaller HAF particles were more effective for reducing the wear of NBR during frictional sliding. The hardness, elastic modulus at 100% elongation, and elongation at break were measured to examine the correlation between the effects of carbon black on the mechanical and tribological properties of the NBR specimens. The wear tracks of the NBR specimens were observed with scanning electron microscopy (SEM). The wear tracks for NBR with different ratios of SRF and HAF showed clearly different abrasion patterns. Mechanisms for the friction and wear behavior of NBR with different sizes of carbon black filler were proposed using evidence from wear track observation, as well as the mechanical and tribological test results.
Topographic and phase imaging in tapping mode atomic force microscopy (TMAFM) has been performed to investigate the effect of unmodified and modified dual phase fillers on the morphology of and the microdispersion of the filler particles in the rubber matrix. The above fillers were modified using acrylate monomer (trimethylol propane triacrylate, TMPTA) or a silane coupling agent (triethoxysilylpropyltetrasulphide, Si-69) followed by electron beam modification at room temperature. Both unmodified and surface treated fillers were incorporated in a styrene-butadiene rubber. The phase images of the above composites show three levels of contrasts that correspond to matrix, filler aggregates, and bound rubber around the filler aggregates. Also, the images further elucidate the aggregated nature of the filler due to modification, which is more pronounced in the case of electron beam modified acrylated filler loaded rubber. The corresponding topographic images have been characterized by various statistical quantities like roughness parameters and one- and two-dimensional power spectral densities (1D-PSD and 2D-PSD). As compared to the control, significant increase in surface roughness is observed in the case of the modified dual phase filler loaded composites. The higher fractal value of these vulcanizates confirms the above fact. AFM study also suggests that the electron beam modification of the above fillers significantly increases the filler-filler and filler-polymer interactions.
Vulcanizing reagent (VR) suspensions with different sulfur additions were mixed with CNTs suspensions and SBR latex, and then powder CNTs/SBR (PSBR) composites were prepared by spray-drying process. Investigations showed that VR additions have significant influences on the properties of CNTs/PSBR composites. With the increment of VR additions, glass transition temperature (Tg) of the composites increased gradually, and reached the maximum when the sulfur addition was 4.0 phr, and then it would decrease if the sulfur addition continued to rise. The elongation at break of the vulcanizates decreased linearly. The tensile strength and hardness reached the maximum when the sulfur addition was 4.0 phr, and almost kept constant when the addition continued to rise. Yet the tear strength reached the maximum when the addition was of 2.5 phr, and then decreased slightly when the addition exceeded 4.0 phr, which was corresponding to the structure designability of the composites affected by the sulfur aggregates in the matrix. Under different temperatures, when the vulcanizing temperature was 150°C, the vulcanizing speed was proper, vulcanizing time was prolonged, and the vulcanizing security was intensified. Compared with the vulcanization of carbon black/PSBR composites, more sulfur additions are needed in the vulcanization of CNTs/PSBR composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
1,2-Butadiene is shown to be a chain terminating/transferring agent in butyllithium-initiated diene polymerization. The influence of 1,2-butadiene on the anionic copolymerization of 1,3-butadiene and styrene is investigated using n-butyllithium as initiator and tetrahydrofuran or N,N,N′,N′-tetramethylethylenediamine as polar additive. A decrease of copolymerization rate is observed on the addition of 1,2-butadiene. On introducing 1,2-butadiene, the number average molecular weight (Mn) decreases and the molecular weight distribution broadens. The vinyl content of copolymer increases slightly with an increase of 1,2-butadiene. During the copolymerization, 1,2-butadiene in the presence of a high ratio of polar additives to n-butyllithium greatly decreases the copolymerization rate, resulting in a lower value of Mn and a narrower molecular weight distribution than that found for a low ratio of polar additives to n-butyllithium. This evolution can be explained by the base-catalyzed isomerization of 1,2-butadiene to form 1-butylene in the presence of polar additives. With an increasing amount of 1,2-butadiene, the vulcanized rubber exhibits an increased rolling resistance and a reduced wet skid resistance owing to the decrease of coupling efficiency. These results further indicate the activity of alkynyllithium derivatives produced by the reaction of alkyllithium and 1-butyne is less than that of the alkyllithium. Copyright © 2007 Society of Chemical Industry
The mechanical behavior of acrylonitrile butadiene rubber (NBR) – organo modified layered silicate was modeled using Design of Experiments (DoE). Response surface methodology (RSM), a DoE tool was used to optimize the formulations for optimal performance of the nanocomposites. A Box-Behnken design with three factors and three levels was used to model the relationship between mechanical properties and levels of ingredients. The factors studied for the design are silica content, nanoclay loading and vulcanization system. The nanocomposites were evaluated for tensile strength, modulus, elongation at break and hardness. The effect of heat aging on mechanical properties was also studied. The predicted properties of the nanocomposites are in good agreement with the experimental results, which confirmed the prognostic ability of response surface methodology. The model equations were used to generate response surfaces and contour plots to study the interaction between the variables. The contour plots were overlaid within the applied constraints to identify the required combination of variables that gives the optimum performance for the nanocomposites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Nanocomposites based on fluoroelastomer and modified and unmodified sodium montmorillonite clays were prepared. Dynamic mechanical thermal analysis was performed on these nanocomposites over a range of temperatures (−60 to +60°C), frequencies (0.032–32 Hz), and strains (0.002%–2%). The results showed that there were significant changes in the glass transition temperature and storage modulus with the addition of small amount (4 phr) of the modified and the unmodified nanofillers. The tan δ peak heights decreased and the storage modulus increased in general, but it was more prominent in the case of the unmodified clay. With the addition of the nanoclays, the cross-over point in the double logarithmic plot of storage modulus (E′) and complex viscosity (η*) with frequency, shifted toward higher frequency. Interestingly, with increasing strain, the nanocomposites demonstrated a sudden upturn in the storage modulus after ∼0.2% strain amplitude, because of the formation of α-crystallization in the elastomer structure. The uniaxial strain before strain sweep experiment increased the storage modulus remarkably. The results were explained with the help of X-ray diffraction and transmission electron microscopy. POLYM. ENG. SCI., 47:1777–1787, 2007. © 2007 Society of Plastics Engineers
Polymer based nanocomposites were prepared using brominated poly(isobutylene-co-paramethylstyrene) (BIMS) rubber and octadecyl amine modified montmorillonite nanoclay. The effect of nature and loading of carbon black on these nanocomposites and the control BIMS was investigated thoroughly using X-ray diffraction technique (XRD), Fourier transform infrared spectroscopy (FTIR), and mechanical properties. The addition of 4 parts of the modified nanoclay to 20 phr N550 carbon black filled samples increased the tensile strength by 53%. Out of the three different grades of carbon black (N330, N550, and N660), N550 showed the best effect of nanoclay. Optimum results were obtained with the 20 phr filler loading. For comparison, china clay and silica at the same loading were used. Fifty-six and 46% improvements in tensile strength were achieved with 4 parts of nanoclay added to the silica and the china clay filled samples, respectively. N330 carbon black (20 parts) filled styrene butadiene rubber (SBR) based nanocomposite registered 20% higher tensile strength with 4 parts of the modified nanoclay. In all the above carbon black filled nanocomposites, the modulus was improved in the range of 30 to 125%. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 443–451, 2005
Carbon black (N-330), organically modified nanoclay (NC) based ternary, particulate nanocomposites comprising of epoxidized natural rubber matrix having 25 mol% of epoxy group (ENR-25) were prepared in an open two-roll mill. Investigations of cure characteristics, dynamic mechanical, tensile, thermal, and morphological characteristics were conducted using Rheometric analysis, Dynamic Mechanical Analysis (DMA), mechanical property evaluation, Thermo-gravimetric analysis (TGA), High Resolution Transmission Electron Microscopy (HR-TEM), respectively, to derive the interrelation among the developed nanostructures inside the composite, crosslinking density, performance properties obtained there from. A satisfactory level of correlation was obtained among various results, which indicated the formation of “nanounit” comprising of N-330 and NC inside ENR-25 matrix. To optimize the nanostructures, ENR based compounds containing various combinations of NC and N-330 was prepared. Thorough and systematic structure-property analyses were performed on those composites. Optimum stoichiometric combination of N-330 and NC inside the ENR-25 matrix was derived (ratio of N-330 and nanoclay in wt% = 20:15), which showed synergistic effect of one filler upon another that was ultimately reflected in their dynamic mechanical and tensile properties. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Dynamic mechanical analysis and dielectric relaxation spectra of conductive carbon black reinforced chlorosulfonated polyethylene (CSM) composites were used to study their relaxation behavior as a function of temperature and frequency, respectively. A marginal increase in glass transition temperature has been observed upto 30 phr carbon black filled polymer composite, beyond which it decreases, which has been explained on the basis of aggregation of filler particles in the polymer matrix. The strain dependent dynamical parameters were evaluated at dynamic strain amplitudes of 0.1–200%. The nonlinearity in storage modulus increases with increase in filler loading. It can be explained on the basis of filler–polymer interaction and aggregation of the filler particulates. The frequency dependent dynamical mechanical analysis has also been studied at frequency range of 0.1–100 Hz. The variation in real and complex part of impedance with frequency has been studied as a function of filler loading. The effect of filler loading on ac conductivity has been observed as a function of frequency. An increase in conductivity value has been observed with increase in filler loading. This can be explained on the basis of formation of conducting paths between filler particulates. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
The nonlinear effect at small strains (Payne effect) has been investigated in the case of silica-filled styrene-butadiene rubber. The originality of this study lies in the careful preparation of samples in order to fix all parameters except one, that is, the modification of the silica surface by grafting silane (introduced at different concentrations) via reactive mixing. The organosilane can be either a coupling or a covering surface treatment with an octyl alkyl chain. A careful morphological investigation has been performed prior to mechanical characterization and silica dispersion was found to be the same whatever the type and the amount of silane. The increasing amount of covering agents was found to reduce the amplitude of the Payne effect. A similar decrease is observed for low coupling agent concentration. At higher concentrations, the evolution turns through an increase due to the contribution of the covalent bonds between the matrix and the silica acting as additional crosslinking. The discussion of the initial modulus was done in the frame of both the filler–filler and filler–polymer models. It is unfortunately not possible to distinguish both scenarios, because filler–filler and filler–matrix interactions are modified in the same manner by the grafting covering agent. On the other hand, the reversible decrease of the modulus versus strain (Payne effect) is interpreted in terms of debonding of the polymeric chains from the filler surface. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 286–298, 2007
Different rubber formulations were designed using nitrile rubber and a mixed crosslinking system consisting of sulfur/accelerator and electron beam radiation. Based on the experimental results, an artificial neural network (ANN) was constructed to simulate the mechanical properties and volume fraction of rubber. The ANN could predict accurately the above properties for a series of nitrile rubber compounds. However, the number of training data played a key role in the ANN predictive quality. In addition, the more complex the nonlinear relation between input and output was, the larger was the number of training dataset required. The predicted results were further validated using another mathematical model. The constructed ANN was verified with a completely different styrene butadiene rubber system. The prediction was found to be extremely good. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2227–2237, 2006
Dynamic mechanical analysis and dielectric relaxation spectra of exfoliated nano graphite reinforced flouroelastomer composites were used to study their relaxation behavior as a function of temperature (−80°C to +40°C) and frequency (0.01 to 105 Hz). The effect of filler loadings on glass transition temperature was marginal for all the composites and Tg value was in the narrow range of 7.8–8.4°C, which has been explained on the basis of relaxation dynamics of polymer chains in the vicinity of fillers. Strain-dependent dynamical parameters were evaluated at dynamic strain amplitudes of 0.01–10%. The nonlinearity in storage modulus has been explained on the concept of filler-polymer interaction and filler aggregation of the nano graphite platelets. The variation in real and complex part of impedance with frequency has been studied as a function of filler. The percolation of the nano graphite as studied by conductivity measurements is also reported.
Electron beam modification of carbon black (N220) and carbon-silica dual phase filler affects the microstructure of carbon black This is confirmed from X-ray diffraction studies. The scanning electron microscopy /energy dispersive X-ray analysis reveals surface oxidation, which is further corroborated from nitrogen and iodine adsorptions. Transmission electron microscopy studies show the aggregation of fillers upon electron beam irradiation Linear fractal dimension calculated by image analysis increases upon irradiation, due to the formation of filler aggregates.
Results of investigations are reported which were devoted to effect of carbon black on the properties of vulcanizates. It is found that the effective volume of carbon black in rubber, as measured by the low-strain equilibrium modulus, is equal to the true volume of carbon plus about half of the occluded volume of rubber calculated from the DBP absorption of the carbon black. In a highly loaded vulcanizate, the secondary network of carbon black raises the modulus measured at low strain and low or moderate temperature. The modulus can be lowered by molecular slippage, especially with thermal blacks, or with graphitized furnace blacks, at elevated temperatures and/or high strains.
Literature- based survey of investigations related to measurement and evaluation of variation of dynamic properties of carbon black- reinforced rubber with strain. Dynamic test apparatus and its operation techniques are described. Effects of temperature, frequency and of special processing or compounding as well as of vulcanization degree on dynamic shear modulus are discussed. Practical aspects of filler agglomeration effects are outlined, with attention to heat build- up in tires. Normalization of moduli and application of domain model.
A series of carbon-silica dual phase fillers have been analyzed using electron spectroscopy for chemical analysis (ESCA) and infrared spectroscopy (IR). These techniques reveal that the silicon in these materials is consistent with that in silica, and the predominant carbon in the carbon phase is similar to the predominant carbon in carbon black. ESCA and IR experiments demonstrate that the carbon-silica dual phase fillers are comprised of composite aggregates, each containing carbon and silica phases. In these dual phase aggregates the silica phase is intimately distributed with the carbon phase. Quantitative ESCA reveals that these dual phase fillers have excess oxygen over the expected stoichiometric amount for the silica present. This excess oxygen is likely due to oxygen groups on the carbon phase. Analysis of the ESCA oxygen Auger lines in combination with various chemical treatments substantiate the presence of carbon phase oxygen groups on the dual phase fillers. Quantitative ESCA in combination with IR spectra of a dual phase filler after removal of the silica phase, by HF treatment, suggests that the carbon phase of the dual phase filler contains more oxygen groups than its carbon black counterpart.
The influence of polyfunctional monomers—tripropyleneglycol diacrylate (TPGDA), trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimetbacrylate (TMPTMA), tetramethylolmethane tetracrylate (TMMT) and triallyl cyanurate (TAC)—on the structural changes of fluorocarbon terpolymer (F content 68%, H 1.4%) in the presence of an electron beam has been investigated with the help of IR spectroscopy (in the ATR mode) and sol-gel analysis. The absorbances at 1397, 1021, 672 and 504 cm−1 due to the C-F group, decrease on irradiation of the mixtures of fluoroelastomer and TMPTA, indicating dehydrofluorination and scission. The concentration of the double bond decreases both in the polyfunctional monomer and its blends with the polymer as a result of grafting and crosslinking. The concentration of the carbonyl group increases with radiation dose in the fluoroelastomer due to aerial oxidation. The effect of trimethylolpropane triacrylate (TMPTA) is to lower the amount of oxidation, especially at relatively higher levels. At a particular radiation dose, the behaviours of TPGDA, TMPTMA, TMMT and TAC based systems are similar to that of the TMPTA based one. The gel content increases with radiation dose. The influence of polyfunctional monomer on gel fraction is more prominent at higher concentrations, where distinct changes are observed at lower doses. At a particular level of multifunctional monomer, the gel fraction is lower for systems based on TPGDA. The ratio of chain scission to crosslinks calculated using the Charlesby-Pinner equation indicates a much higher crosslinking efficiency with polyfunctional monomer-fluorocarbon rubber matrix as compared to the control rubber.
The dependence of electrical resistivities on the temperature of different polymer systems (including rubbers and plastic/rubber blends) loaded with carbon blacks (including oxidized and normal carbon blacks) were studied. We found that polymer-carbon black interactions could greatly influence the electrical resistivity and temperature relations of the polymer composites. The polymer blends filled with oxidized carbon black, or the elastomer which has polar functional groups filled with carbon black, have a very weak negative temperature coefficient (NTC) effect, which is due to the strong polymer-filler interactions. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1885–1890, 1997
Dynamic properties such as shear modulus, loss modulus, and loss factor were obtained at a low strain amplitude over a wide range of frequencies and temperatures on vulcanizates filled with carbon black, silica, and carbon–silica dual-phase filler. The data were shifted along the frequency scale. Instead of a single smooth master curve, a pseudomaster curve with a feather-like structure is obtained. This effect is especially pronounced for the loss factor. Multiple factors may be responsible for this. Among others, filler networking and polymer–filler interaction may play a dominant role. The effect of the carbon–silica dual-phase filler on the overall dynamic properties of the vulcanizates is similar to that of silica. Their tan δ values are much lower at lower frequencies and are relatively higher at higher frequencies. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1240–1249, 2000
Electron beam modification of carbon black (N220) and carbon-silica dual phase filler has been carried out at room temperature. The increase in oxygen to carbon ratio (O/C) determined by using Electron spectroscopy for chemical analysis (ESCA) is observed. Fourier transform infra-red spectroscopy (FT-IR) studies detect a new peak at 801 cm–1 upon electron beam irradiation, which is due to Si-C stretching in the case of modified dual phase fillers. The absence of the peak at 3400 cm–1 and the presence of the peak at 1720 cm–1 due to aliphatic ester stretching confirm the presence of trimethylol propane triacrylate (TMPTA) on the surface. Similarly, the absence of peak band at 3400 cm–1 confirms chemical interaction of triethoxysilylpropyl tetrasulphide (Si-69). A decrease in dispersive component (s
d) and an increase in polar component (s
p) of the surface energy corroborate surface oxidation.