SBR-clay-carbon black hybrid nanocomposites for tire tread application

Styrene butadiene rubber-organoclay nanocomposites were prepared with Cloisite 15A via melt intercalation. X-ray diffraction and transmission electron microscopy indicated that the nanostructures are partially exfoliated and intercalated. The nanocomposites exhibited great improvements in tensile strength and tensile modulus. The incorporation of organoclay gave rise to considerable reduction of tan delta and increase in storage modulus in the rubbery region. It is shown that after 6 phr (parts per hundred rubber) clay loading there is not much increase in the properties. The effect of carbon black (N330) on mechanical properties, dynamic mechanical properties, heat build up, abrasion resistance in the nanocomposites having the optimized clay level (6 phr) was investigated. Optimum results were obtained with the addition of 25 phr carbon black. For comparison with the 6phr nanoclay and 25phr N330 (high abrasion furnace carbon black) filled SBR composites, 40 phr N330 filled SBR composites was used. The 6phr organoclay and 25phr N330 filled SBR nanocomposite showed better properties than 40phr carbon filled SBR compound. These results indicate that 6phr organoclay can be replaced by 15 phr carbon black from the conventional SBR-carbon black based tire tread compounds. The Dynamic mechanical analyzer (DMA) results revealed that the new tire tread compound gives better rolling resistance and comparable wet grip resistance and lower heat build up than that of conventional tread compound.     

Influence of carbon black in polychloroprene organoclay nanocomposite with improved mechanical,electrical and morphology characteristics

Abstract

The effect of carbon black on nanoclay filled polychloroprene (CR) composites has been investigated. The nanoclay loading is fixed at 5 part per hundred rubbers (phr), and carbon black loading varied from 5 to 20 phr in rubber compounds. The rubber nanocomposites are prepared in laboratory by mixing in two-roll mill. The addition of nanoclay enhances mechanical properties especially tear strength and decreases water absorption without change in electrical properties compared to gum rubber vulcanisates. Wide angle X-ray diffraction and transmission electron microscopy are used to study the microstructure of CR nanocomposites. The addition of 5 parts of nanoclay to 15 phr carbon black filled samples shows synergistic effect between the fillers and suggests that the reinforcement is due to a more developed filler network formation in hybrid filler system than that in single phase filler. Significant improvement in mechanical, electrical and low water absorption properties has been obtained with these nanoclay and carbon black filled rubber nanocomposites. The paper concludes that nanocomposites containing a mixture of organoclay and carbon black in right proportion can be a substitute for rubber components used in underwater cable and device encapsulation applications.     

Rheological behavior of brominated isobutylene‐co‐paramethylstyrene: Effect of fillers,oil and blending with EPDM

The melt flow properties of unfilled and filled brominated isobutylene‐co‐paramethylstyrene (BIMS) were measured by means of a capillary viscometer at three different temperatures (90°C, 110°C and 130°C) and four different shear rates (61, 122, 245 and 306 s^?1). The effect of addition of EPDM rubber on melt flow properties of unfilled BIMS was also studied. Evaluation of the processability was done by measuring the extrudate roughness (ER) of the extrudates obtained from the MPT. The viscosity of the systems decreased with the shear rate, indicating their pseudoplastic or shear thinning nature. As expected, the viscosity of BIMS increased with the addition of fillers and decreased with the addition of oil. For the neat systems, viscosity increased with the addition of EPDM, and the blends showed a positive deviation, indicating interdiffusion of the polymer chains across the phase boundaries. The activation energy of the filled systems at constant filler loading increased with increasing filler surface area (N330 > N550 > N774, each at 30 phr loading), and filler loading (50 > 30 > 10 phr, for N330) and decreased with the addition of oil (2.5 > 5.0 > 7.5 phr, for system containing 30 phr of N330). The silica filled system showed a higher activation energy and ER than the carbon black‐filled systems. With addition of N330 and N550 carbon blacks to BIMS, the extrudate roughness (ER) decreased, whereas it increased with the addition of N774 carbon black. With an increase in filler loading, ER initially increased and then decreased as compared to the neat system. For the filled systems, ER initially decreased up to 5 phr of oil, beyond which it increased.     

A comparative study of aging characteristics and thermal stability of oil palm ash,silica, and carbon black filled natural rubber vulcanizates

Filler‐filled natural rubber (NR) vulcanizates were prepared by conventional laboratory‐sized two roll mills and cured using sulfuric system. The effect of thermal aging on physical properties and thermogravimetric analysis (TGA) of oil palm ash (OPA) and commercial fillers (i.e., silica vulkasil C and carbon black N330)‐filled NR vulcanizates at respective optimum loading and equal loading were studied. Before aging, the OPA‐filled vulcanizates showed comparable optimum strength as carbon black‐filled vulcanizates. The hardening of aged filler‐filled NR vulcanizates happened after aging, thereby tensile strength and elongation at break reduced while the modulus increased. Fifty phr carbon black‐filled vulcanizates showed better retention in tensile properties as compared to silica (10 phr) and OPA (1 phr). This was attributed to the addition of different filler loading and this finding was further explained when equal loading of filler‐filled vulcanizates was studied. Fourier transform infra‐red analysis showed chemical structure had changed and tensile fractured surface exhibited smooth appearance due to the deterioration in tensile properties after aging. TGA also denoted the thermal stability was depending on the amount of filler loading. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4474–4481, 2013     

Effects of partial replacement of commercial fillers by recycled poly(ethylene terephthalate) powder on the properties of natural rubber composites

Commercial fillers, including carbon black (N550), halloysite nanotubes (HNTs), and precipitated silica, were replaced by recycled poly(ethylene terephthalate) powder (R‐PET) in natural rubber (NR) composites. Five different compositions of NR/N550/R‐PET, NR/HNTs/R‐PET, and NR/silica/R‐PET compounds, i.e., 100/20/0, 100/15/5, 100/10/10, 100/5/15, and 100/0/20 parts per hundred rubber (phr), were prepared on a two‐roll mill. The curing behavior, tensile properties, and morphological characteristics of the natural rubber composites were investigated. The results indicated that the replacement of carbon black, HNTs, and silica by R‐PET decreased the tensile strength and tensile modulus, such that NR/silica/R‐PET composites showed the lowest effect, followed by NR/HNTs/R‐PET and NR/N550/R‐PET composites. The negative effect on these properties can be explained by the decrease of crosslink density. The curing results revealed that with the replacement of carbon black by R‐PET, the scorch time and cure time decreased, but that the NR/HNTs/R‐PET and NR/silica/R‐PET composites exhibited the opposite trend. Scanning electron microscopy investigation of tensile fracture surfaces confirmed that the co‐incorporation of N550/R‐PET improved the dispersion of R‐PET and enhanced the interaction between the fillers and NR matrix more than R‐PET and silica/R‐PET hybrid fillers. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers     

Effect of rubber matrix type on the morphology and reinforcement effects in carbon black‐nanoclay hybrid composites—A comparative assessment

Carbon black (B)–nanoclay (NC) hybrid composites, based on millable polyurethane and brominated isoprene isobutylene rubber (BIIR), were prepared. The carbon black loading was fixed at 20 phr and organically modified sodium montmorillonite clay loading varied from 5 to 20 phr in each rubber compounds. The nanocomposites were prepared in laboratory by mixing two‐roll mill. The state of dispersion of the layered silicate was studied by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM results indicated intercalation of PU and BIIR into the silicate interlayers, followed by exfoliation of the silicate layers into the elastomer matrices. However, the level of intercalation and exfoliation varied considerably with the type of elastomer. The reinforcing effects obtained were found to depend strongly on the extent and degree of the dispersion of the carbon black and silicate layers into the rubber matrices. Mechanical and dynamic mechanical properties were evaluated for each composite. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

黏土/天然橡胶纳米复合材料的制备及性能

利用乳液插层法制备了黏土／天然橡胶纳米复合材料,研究了该复合材料的力学性能、应力应变行为、耐磨性、气体阻隔性和耐老化性能。结果表明,黏土／天然橡胶纳米复合材料与高耐磨炭黑(N330)、白炭黑增强橡胶相比,邵尔A型硬度、定伸应力和撕裂强度较高,拉伸强度相当。黏土、N330以及白炭黑对天然橡胶的拉伸结晶有影响,填料用量对材料拉伸强度的影响存在最佳值。黏土／天然橡胶纳米复合材料具有良好的耐磨性、气体阻隔性和耐老化性能。     

Swelling and mechanical properties of (acrylonitrile‐butadiene rubber)/(hydrogenated acrylonitrile‐butadiene rubber) blends with precipitated silica filled in gasohol fuels

This work studied the effects of hydrogenated acrylonitrile‐butadiene rubber (HNBR) and precipitated silica (PSi) loadings in acrylonitrile‐butadiene rubber (NBR) filled with 60 parts per hundred of rubber (phr) of carbon black (CB) for oil‐resistant seal applications in contact with gasohol fuel. The cure characteristics, mechanical properties, and swelling behavior of HNBR/NBR blends reinforced with PSi before and after immersion in ethanol‐based oils (E10, E20, and E85) were then monitored. This work studied the effects of PSi loading in rubber compounds on the mechanical properties of the rubber blends. The results suggested that the scorch time of CB‐filled NBR/HNBR was not affected by HNBR loading, but the cure time, Mooney viscosity, and torque difference increased with HNBR content. The swelling of the blends in E85 oil were relatively low compared with those in E10 and E20 oils. The recommended NBR/HNBR blend ratio for oil‐resistant applications was 50/50. Tensile strength and elongation at break before and after immersion in gasohol oils increased with HNBR loading, and the opposite effect was found for tensile modulus and hardness. PSi filler had no effect on scorch time, but decreased the cure time of the blends. The swelling level of the blends slightly decreased with increasing PSi content. The recommended silica content for optimum reinforcement for black‐filled NBR/HNBR blend at 50/50 was 30 phr. The results in this work suggested that NBR/HNBR blends reinforced with 60 phr of CB and 30 phr of silica could be potentially used for rubber seals in contact with gasohol fuels. J. VINYL ADDIT. TECHNOL., 22:239–246, 2016. © 2014 Society of Plastics Engineers     

新型偶联剂对橡胶力学性能的影响

本文讨论了新型偶联剂用量对陶土填充橡胶与炭黑填充橡胶动态性能与力学性能的影响．并且用红外光谱对偶联剂改性陶土表面进行了表征。结果表明：该偶联剂明显提高硫化胶的动态性能、撕裂强度及陶土填充橡胶的拉伸强度，其用量超过１．５重量份对硫化胶的力学性能有不良影响。     

Efficacy of Novel Nanoclay in Autohesive Tack of Brominated Isobutylene-co-p-Methylstyrene (BIMS) Rubber

Autohesive tack is the ability of two unvulcanized rubber surfaces to resist separation after they are brought into contact for a short period under light pressure. In this work, the effect of unmodified montmorillonite (MMT) nanoclay on autohesive tack of brominated isobutylene-co-p-methylstyrene (BIMS) rubber was investigated by a 180° peel test. The nanocomposites were characterized using X-ray diffraction (XRD) and atomic force microscopy (AFM). The autohesive tack strength dramatically increased with nanoclay concentration up to 8 phr, beyond which it reached apparently a plateau at 16 phr of nanoclay concentration. The tack strength of 16 phr of nanoclay loaded sample was nearly 158% higher than the tack strength of neat BIMS rubber. Various tack governing factors such as green strength, creep compliance, entanglement molecular weight, relaxation time, self-diffusion coefficient, and monomer friction coefficient were analyzed. The addition of nanoclay reduced the extent of molecular diffusion at the tack junction by reducing the chain mobility; however, the diffusion was still sufficient to achieve bond formation. Furthermore, the less diffused chains of the nanocomposite samples showed greater bond breaking resistance due to an increase in cohesive strength, onset of transition zone relaxation time, and monomer friction coefficient value of the BIMS matrix owing to the nanoclay reinforcement. On the other hand, the more diffused chains of the unfilled sample exhibited facile chain separation due to the poor cohesive strength of the BIMS matrix.     

On the potential of organoclay with respect to conventional fillers (carbon black,silica) for epoxidized natural rubber compatibilized natural rubber vulcanizates

Onium modified montmorillonite (organoclay) was compounded with natural rubber (NR) in an internal mixer and cured by using a conventional sulfuric system. Epoxidized natural rubber with 50 mol % epoxidation (ENR 50) in 10 parts per hundred rubber (phr) was used as a compatibilizer in this study. For comparison purposes, two commercial fillers: carbon black (grade N330) and silica (grade vulcasil‐S) were used. Cure characteristics were carried out on a Monsanto MDR2000 Rheometer. Organoclay filled vulcanizate showed the lowest values of torque maximum, torque minimum, scorch, and cure times. The kinetics of cure reaction showed organoclay could behave as a cocuring agent. The mechanical testing of the vulcanizates involved the determination of tensile and tear properties. The improvement of tensile strength, elongation at break, and tear properties in organoclay filled vulcanizate were significantly higher compared to silica and carbon black filled vulcanizates. In terms of reinforcing efficiency (RE), organoclay exhibited the highest stiffness followed by silica and carbon black filled vulcanizates. Scanning electron microscopy revealed that incorporation of various types of fillers has transformed the failure mechanism of the resulting NR vulcanizates compared to the gum vulcanizates. Dynamic mechanical thermal analysis (DMTA) revealed that the stiffness and molecular relaxation of NR vulcanizates are strongly affected by the filler–rubber interactions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2438–2445, 2004     

Design and analysis of single-factor experiments: Analysis of variance of the effect of rice husk ash and commercial fillers in NR compounds

Summary White rice husk ash (WRHA) and black rice husk ash (BRHA) were incorporated into natural rubber (NR) using a laboratory-sized two-roll mill. A conventional vulcanization system was used for curing and physical tests of the NR vulcanized involved determining of tensile and tear resistances. For comparison purposes, precipitated silica (Zeosil-175) and carbon black (N774) were used too. Using the analysis of variance of single-factor experiments, it can be concluded that: BRHA is non-reinforcing filler and its use is limited to 20 phr; WRHA is semi-reinforcing filler and the variation of filler loading (0 up to 50 phr) causes the maximum variation upon tensile strength of NR compounds; and, that although carbon black and silica are reinforcing fillers, a real reinforcement is reached up to 20 phr for tensile strength.     

Effect of nanoclay on the mechanical and damping properties of aramid short fibre‐filled styrene butadiene rubber composites

The effect of nanoclay loading on the alteration of tensile and dynamic mechanical properties of aramid short fibre‐filled styrene butadiene rubber composites was investigated. In all the composites, 20 phr of N330 black was used. Dynamic mechanical thermal analysis was used to investigate the viscoelastic damping at lower dynamic strains. Compressive hysteresis was evaluated to characterize higher strain static damping properties. Matrix–fibre interaction and filler distribution were investigated using morphological analyses. Matrix–filler interface, estimated by the half height width of the tan δ peak, plays a major role in energy dissipation. The matrix–fibre interaction parameter shows a similar trend with low strain tensile stress values. Nanoclay addition to the composites leads to improved elongation at break and frequency damping properties. Compressive hysteresis reflects no improvement of hysteresis with nanoclay loading. Dynamic storage moduli, matrix–fibre interaction parameter and energy dissipation properties of the short fibre‐filled composites are negatively affected by nanoclay addition. However, ultimate elongation is improved markedly on nanoclay addition. In respect of tensile strength and elongation at break values, two composite samples (KF5NC10 and KF10NC10) offer optimum properties. Copyright © 2009 Society of Chemical Industry     

Safe amine based zinc dithiocarbamates for the vulcanization of carbon black reinforced natural rubber

Binary combination of three safe amine based synthesized zinc dithiocarbamates (ZDC), namely zinc (N‐benzyl piperazino) dithiocarbamate (ZBPDC), zinc (N‐ethyl piperazino) dithiocarbamate (ZEPDC), and zinc (N‐phenyl piperazino) dithiocarbamate (ZPPDC) with mercapto benzothiazole disulfide (MBTS) as an effective accelerator system for the vulcanization of carbon black (N330, N550, and N774) filled natural rubber (NR) composites are studied. A comparison between the safe amine based zinc dithiocarbamates with the unsafe zinc dimethyl dithiocarbamate (ZDMC) in the light of mechanical and aging resistance behavior, introduces the non carcinogenic rubber additives in the filled vulcanization of rubber. Both accelerator and filler have the major importance for improving the mechanical as well as aging resistance behavior of the resultant vulcanizate. Variation in the filler and also filler to oil ratio are done to optimize the mechanical properties. SEM studies of different types of filler with different amounts show that N330 at 30 phr loading composites forms more homogeneity and less aggregated structures. Natural rubber systems with N330 carbon black show the best results with respect to tensile strength, but after the aging N774 carbon black filled system indicates better retention in the tensile strength. ZPPDC‐MBTS accelerated vulcanizate shows the better age resistance behavior than ZDMC‐MBTS accelerated vulcanizate. From both the points of age resistance and mechanical properties, ZBPDC‐MBTS accelerator system is the suitable substitute for ZDMC‐MBTS accelerated system in the filled vulcanization of natural rubber composites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39988.     

Preparation and characterization of high performance exfoliated montmorillonite/silicone rubber nanocomposites with enhanced mechanical properties

Highly exfoliated and intercalated silicone rubber (SR) nanocomposites based on natural montmorillonite (Cloisite Na⁺) and organically modified montmorillonite (Cloisite 30B and Cloisite 20A) were successfully prepared by melt‐mixing technique. Dispersion of the nanoclays in the rubber nanocomposites was subsequently investigated. As indicated by the X‐ray diffraction (XRD) analysis, intercalation, and exfoliation of the clay particles in the nanocomposites was achieved at less than 8 parts per hundred (phr) rubber by weight, irrespective of the initial interlayer spacing of the nanoclay particles. Both Cloisite Na⁺ and Cloisite 30B were spontaneously transformed into exfoliated microstructures during the vulcanisation stage. Overall, the use of the nanoclays in silicone rubber improved the Young's modulus, tensile strength, and elongation at break by more than 50% as compared with the control rubber. In addition, this work provided a fresh insight into the way intercalated and exfoliated morphologies affect mechanical properties of silicone rubber nanocomposites. It was shown that the exfoliated Cloisite Na⁺ yielded outstanding mechanical properties with low hysteresis at the same loading of the exfoliated Cloisite 30B and intercalated Cloisite 20A organoclays. As expected, the formation of crosslinks affected the mechanical properties of the rubber vulcanizate significantly. POLYM. ENG. SCI., 53:2603–2614, 2013. © 2013 Society of Plastics Engineers     

Use of rice husk ash as filler in natural rubber vulcanizates: In comparison with other commercial fillers

Rice husk ash is mainly composed of silica and carbon black remaining from incomplete combustion. Both silica and carbon black have long been recognized as the main reinforcing fillers used in the rubber industry to enhance certain properties of rubber vulcanizates, such as modulus and tensile strength. In this study, two grades of rice husk ash (low‐ and high‐carbon contents) were used as filler in natural rubber. Comparison was made of the reinforcing effect between rice husk ashes and other commercial fillers such as talcum, china clay, calcium carbonate, silica, and carbon black. Fourier transform infrared spectroscopy (FTIR) analysis was employed to study the presence of functional groups on the ash surface. The effect of silane coupling agent, bis(3‐triethoxysilylpropyl)tetrasulfane (Si‐69), on the properties of ash‐filled vulcanizates was also investigated. It was found that both grades of rice husk ash provide inferior mechanical properties (tensile strength, modulus, hardness, abrasion resistance, and tear strength) in comparison with reinforcing fillers such as silica and carbon black. However, the mechanical properties of the vulcanizates filled with rice husk ash are comparable to those filled with inert fillers. The addition of silane‐coupling agent has little effect on the properties of the ash‐filled vulcanizates. This is simply due to the lack of silanol groups on the ash surface. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2485–2493, 2002     

Epoxy-resin-cured carboxylated nitrile rubber

Curing of carboxylated nitrile rubber (XNBR) with epoxy resin in presence of different fillers has been studied. It was observed that 7.5 phr of resin give a compromise combination of properties in FEF black (N 550)-filled vulcanizates at 40 phr loading. Further studies at different loadings of black, reinforcing silica and clay were done at 7.5 phr resin. Technical properties at different filler loadings have been determined. Polymer-filler interaction involving FEF black, silica, and clay was examined by a Kraus plot and the equation of Lorenz and Parks. Silica and carbon black give a similar type of reinforcement, but clay shows nonreinforcing characteristics. In the case of carbon black–XNBR system, polymer-filler attachment is similar to that existing in carbon black–natural rubber system. In the case of silica, reaction of the silanol group with the epoxide group of the epoxy resin and the carboxyl group of the base polymer may be responsible for the polymer-filler attachment. Scanning electron microscopy (SEM) studies of the fracture surfaces corroborate the findings on technical properties and polymer-filler interaction.     

Influence of nanoclay on adhesion of EPDM vulcanizate

The influence of unmodified clay, Cloisite Na⁺ on adhesion between prevulcanized EPDM rubber and unvulcanized EPDM rubber containing nanoclay was investigated using 180° peel test. The rubber showed improvement in peel strength with increasing clay concentration up to 4 phr, beyond which it decreased. A maximum of 51% improvement in peel strength was obtained for 4 phr Cloisite Na⁺. This was attributed to enhanced tensile strength, monomer friction coefficient, marginal improvement of polarity and micro-roughness of the clay filled rubber. At higher clay loading (8 phr), the peel strength reduced due to formation of boundary layer of Zn-stearate, accelerators and clay on the outermost surface, diffusion of the fewer rubber chains, agglomeration of the clay particles and increased modulus of the rubber.     

Cure Characteristics and Mechanical Properties of Natural Rubber–Layered Clay Nanocomposites

The effect of interlayer distance of nanoclay on mechanical properties, cure characteristics, and swelling resistance of natural rubber (NR) in varying clay proportion were studied. X-ray diffraction results of nanocomposite with 10 phr of nanoclay showed the formation of an intercalated structure. The rate of vulcanization and maximum torque value of the nanocomposite are higher than the gum compound. Nanocomposites with clay having higher interlayer distance shows superior mechanical properties. Mechanical properties gradually increase with increase in clay loading up to 10 phr. A 50% increase in tensile strength and about 150% increase in modulus at 300% elongation were observed for the nanocomposite with 10 phr clay loading. Better barrier properties offered by the nanocomposites due to the presence of tortous path was confirmed by the Nielson's model.     

Kaolin modified with sodium salt of rubber seed oil as a reinforcing filler for blends of natural rubber,polybutadiene rubber and acrylonitrile–butadiene rubber

Blends of natural rubber (NR) and synthetic rubbers are widely used in the rubber industry to meet specific performance requirements. Further, the emerging field of organomodified clay/rubber nanocomposites could provide a host of novel materials having a unique combination of properties to meet various stringent service conditions. Previous studies have shown that at very low dosages, china clay (kaolin) modified with sodium salt of rubber seed oil (SRSO) improved the cure characteristics and physico‐mechanical properties of NR. Results of the present study show improved cure characteristics and physico‐mechanical properties for blends of NR with butadiene rubber and nitrile rubber containing 4 phr of SRSO‐modified kaolin as indicated by reduction in optimum cure time along with higher tensile strength, tensile modulus and elongation at break for their vulcanizates as compared to those containing unmodified kaolin. The SRSO‐modified kaolin/rubber nanocomposites showed improved flex resistance, reduced heat build‐up, tan delta and loss modulus and higher chemical crosslink density index, indicating a reinforcing effect of the SRSO‐modified kaolin, enabling the nanocomposites to have potential industrial applications. © 2015 Society of Chemical Industry