Effect of the addition of acrylonitrile/ethylene–propylene–diene monomer (EPDM)/styrene graft copolymer on the morphology–properties relationships in poly(styrene‐co‐acrylonitrile)/EPDM rubber blends

Blends of poly(styrene‐co‐acylonitrile) (SAN) with ethylene–propylene–diene monomer (EPDM) rubber were investigated. An improved toughness–stiffness balance of the SAN/EPDM blend was obtained when an appropriate amount of acrylonitrile–EPDM–styrene (AES) graft copolymer was added, prepared by grafting EPDM with styrene–acrylonitrile copolymer, and mixed thoroughly with both of the two components of the blend. Morphological observations indicated a finer dispersion of the EPDM particles in the SAN/EPDM/AES blends, and particle size distribution became narrower with increasing amounts of AES. Meanwhile, it was found that the SAN/EPDM blend having a ratio of 82.5/17.5 by weight was more effective in increasing the impact strength than that of the 90/10 blend. From dynamic mechanic analysis of the blends, the glass‐transition temperature of the EPDM‐rich phase increased from ?53.9 to ?46.2°C, even ?32.0°C, for the ratio of 82.5/17.5 blend of SAN/EPDM, whereas that of the SAN‐rich phase decreased from 109.2 to 108.6 and 107.5°C with the additions of 6 and 10% AES copolymer contents, respectively. It was confirmed that AES graft copolymer is an efficient compatibilizer for SAN/EPDM blend. The compatibilizer plays an important role in connecting two phases and improving the stress transfer in the blends. Certain morphological features such as thin filament connecting and even networking of the dispersed rubber phase may contribute to the overall ductility of the high impact strength of the studied blends. Moreover, its potential to induce a brittle–ductile transition of the glassy SAN matrix is considered to explain the toughening mechanism. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1685–1697, 2004     

Preparation and characterization of acrylonitrile–styrene–methylmethacrylate terpolymer as a compatibilizer for rubber blends

Acrylonitrile‐co‐styrene‐co‐methylmethacrylate (AN‐S‐MMA) terpolymer was prepared by bulk and emulsifier‐free emulsion polymerization techniques. The bulk and emulsion terpolymers were characterized by means of Fourierr transform infrared spectroscopy, ¹³C nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography, thermal gravimetric analysis, and elemental analysis. The kinetics of the terpolymerization were studied. The terpolymers were then incorporated into butadiene—acrylonitrile rubber (NBR)/ethylene propylene diene monomer rubber (EPDM) blends and into chloroprene rubber (CR)/EPDM blend. The terpolymers were then tested for potential as compatibilizers by using scanning electron microscopy and differential scanning calorimetry. The terpolymers improved the compatibility of CR/EPDM and NBR/EPDM blends. The physicomechanical properties of CR/EPDM and NBR/EPDM blend vulcanizates revealed that the incorporation of terpolymers was advantageous, since they resulted in blend vulcanizates with higher 100% moduli and with more thermally stable mechanical properties than the individual rubbers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3143–3153, 2003     

Evidences of solvent‐induced miscibility in polychloroprene‐co‐ethylene‐propene diene terpolymer blends

Solvent dependent changes in the compatibility behavior of Polychloroprene/Ethylene–propylene–diene terpolymer blends (CR/EPDM) have been investigated using dilute solution viscometry and solvent permeability analysis. To predict the compatibility of rubber blends of different compositions in solvents of different cohesive energy densities, Huggins interaction parameter (ΔB), hydrodynamic interaction (Δη) and Sun's parameter (α) were evaluated from the analysis of the specific and reduced viscosity data of two and three‐component polymer solutions. Miscibility criteria were not satisfied for CR/EPDM blends over the entire composition range in toluene, xylene, and carbon tetrachloride (CCl₄), however, a narrow miscibility domain was observed in chloroform (CHCl₃) for CR/EPDM/CHCl₃ system. These results were further corroborated with the analysis of heat of mixing (ΔH_m) and polymer–polymer interaction parameter (χ₁₂), for all rubber blend compositions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

In‐situ polymerized phenolic resin for reinforcement of chloroprene and ethylene–propylene rubber vulcanizates

Phenolic resin (PF) was incorporated into rubbers by in situ polymerization at the vulcanization conditions of rubbers. The PF with a localized three‐dimensional network structure was formed in chloroprene rubber (CR), whereas the fabric PF was formed in ethylene–propylene rubber (EPDM). The study results showed that the PF phase was effective on reinforcing these rubbers. Depending on the morphologies of the formed PF phases, various rubber properties could be significantly enhanced. In the case of CR rubber, the tensile strength, tear strength, and modulus could be considerably enhanced, but the elongation and resilience properties were limitedly affected by PF addition. For EPDM rubber, all mechanical properties were improved, particularly the elongation, about 26% increase. The substantial improvements of mechanical properties of CR and EPDM rubbers were attributed to their morphology, high flexibility, moderate stiffness, and excellent bonding with rubber matrix. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Study on the milling behavior of chloroprene rubber blends with ethylene–propylene–diene monomer rubber,polybutadiene rubber,and natural rubber

The viscoelastic properties of the blends of chloroprene rubber (CR) with ethylene–propylene–diene monomer rubber (EPDM), polybutadiene rubber (BR), and natural rubber (NR) at different temperature were studied using rubber processing analyzer (RPA). Mooney viscosities of compounds were measured and tight milling and sheeting appearance were observed on a two‐roll mill. The results showed that Mooney viscosities and the elastic modulus of the blends decreased with the increase of the temperature from 60 to 100°C. And the decreasing trends of pure CR, pure NR, and CR/NR blend compounds were more prominent than that of pure EPDM, pure BR, CR/EPDM, and CR/BR blend compounds. For CR/EPDM blend compounds, the decreasing trend became slower with the increase of EPDM ratio in the blend. Compared with pure CR, pure NR and CR/NR blend compounds, pure EPDM, pure BR compounds, and the blend compounds of CR/EPDM and CR/BR showed less sensibility to temperature and they were less sticky to the metal surface of rolls and could be kept in elastic state at higher temperature, easy to be milled up and sheeted. At the same blend ratio and temperature, the property of tight milling of the blends decreased in the sequence of CR/EPDM, CR/BR, and CR/NR. With the increase of EPDM, BR, or NR ratio in CR blends, its property of tight milling was improved. POLYM. COMPOS., 28:667–673, 2007. © 2007 Society of Plastics Engineers     

The dynamic mechanical analysis,impact, and morphological studies of EPDM–PVC and MMA‐g‐EPDM–PVC blends

The dynamic mechanical studies, impact resistance, and scanning electron microscopic studies of ethylene propylene diene terpolymer–poly(vinyl chloride) (EPDM–PVC) and methyl methacrylate grafted EPDM rubber (MMA‐g‐EPDM)–PVC (graft contents of 4, 13, 21, and 32%) blends were undertaken. All the regions of viscoelasticity were present in the E′ curve, while the E″ curve showed two glass transition temperatures for EPDM–PVC and MMA‐g‐EPDM–PVC blends, and the T_g increased with increasing graft content, indicating the incompatibility of these blends. The tan δ curve showed three dispersion regions for all blends arising from the α, β, and Γ transitions of the molecules. The sharp α transition peak shifted to higher temperatures with increasing concentration of the graft copolymer in the blends. EPDM showed less improvement while a sixfold increase in impact strength was noticed with the grafted EPDM. The scanning electron microscopy micrographs of EPDM–PVC showed less interaction between the phases in comparison to MMA‐g‐EPDM–PVC blends. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1959–1968, 1999     

Miscibility of blends of ethylene‐propylene‐diene terpolymer and polypropylene

The miscibility of polymers is not only an important basis for selecting a proper blending method, but it is also one of the key factors in determining the morphology and properties of the blends. The miscibility between ethylene‐propylene‐diene terpolymer (EPDM) and polypropylene (PP) was explored by means of dynamic mechanical thermal analysis, transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). The results showed that a decrease in the PP content and an increase of the crosslinking density of EPDM in the EPDM/PP blends caused the glass‐transition temperature peaks of EPDM to shift from a lower temperature to higher one, yet there was almost no variance in the glass‐transition temperature peaks of PP and the degree of crystallinity of PP decreased. It was observed that the blends prepared with different mixing equipment, such as a single‐screw extruder and an open mill, had different mechanical properties and blends prepared with the former had better mechanical properties than those prepared with the latter. The TEM micrographs revealed that the blends were composed of two phases: a bright, light PP phase and a dark EPDM phase. As the crosslinking degree of EPDM increased, the interface between the phases of EPDM and PP was less defined and the EPDM gradually dispersed in the PP phase became a continuous phase. The results indicated that EPDM and PP were both partially miscible. The mechanical properties of the blends had a lot to do with the blend morphology and the miscibility between the blend components. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 315–322, 2002     

Dynamic mechanical properties of polypropylene‐g‐maleic anhydride and ethylene–propylene–diene terpolymer blends: Effect of blend preparation methods

In this work, we attempted two different ways of processing to improve interfacial adhesion of polypropylene (PP) and ethylene–propylene–diene terpolymer (EPDM) by introducing maleic anhydride (MAH); In one way, the in situ grafting and dynamic vulcanization (ISGV) were performed simultaneously from PP and EPDM with MAH in the presence of dicumyl peroxide (DCP) in an intensive mixer. In another way, PP was first grafted with MAH and then the PP‐g‐MAH was blended with EPDM in the intensive mixer in the presence of DCP by the dynamic vulcanization (DV). It was found that the glass transition temperatures (T_gs) of both PP and EPDM phases were shifted to higher temperature as the EPDM content increased for the blends prepared by both IGSV and DV methods, mainly due to the crosslinking of EPDM. The higher T_gs and larger storage moduli were observed for the blends prepared by the ISGV method than those prepared by the DV method, while the morphology showed that the size reduction of dispersed particles in latter blends was larger than that of the former blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2777–2784, 2000     

Influence of calcium carbonate filler and mixing type process on structure and properties of styrene–acrylonitrile/ethylene–propylene–diene polymer blends

The properties of styrene–acrylonitrile (SAN) and ethylene–propylene–diene (EPDM) blends containing different types of calcium carbonate filler were studied. The influence of mixing type process on the blend properties was also studied. Two different mixing processes were used. The first one includes mixing of all components together. The other process is a two‐step mixing procedure: masterbatch (MB; EPDM/SAN/filler blend) was prepared and then it was mixed with previously prepared polymer blend. Surface energy of samples was determined to predict the strength of interactions between polymer blend components and used fillers. The phase morphology of blends and their thermal and mechanical properties were studied. From the results, it can be concluded that the type of mixing process has a strong influence on the morphological, thermal, and mechanical properties of blends. The two‐step mixing process causes better dispersion of fillers in blends as well as better dispersion of EPDM in SAN matrix, and therefore, the finest morphology and improved properties are observed in blends with MB. It can be concluded that the type of mixing process and carefully chosen compatibilizer are the important factors for obtaining the improved compatibility of SAN/EPDM blends. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Dynamic mechanical analysis of ethylene–propylene–diene monomer rubber and styrene–butadiene rubber blends

The effects of blend ratio, crosslinking systems, and fillers on the viscoelastic response of ethylene–propylene–diene monomer (EPDM)/styrene–butadiene rubber (SBR) blends were studied as functions of frequency, temperature, and cure systems. The storage modulus decreased with increasing SBR content. The loss modulus and loss tangent results showed that the EPDM/SBR blend vulcanizate containing 80 wt % EPDM had the highest compatibility. Among the different cure systems studied, the dicumyl peroxide cured blends exhibited the highest storage modulus. The reinforcing fillers were found to reduce the loss tangent peak height. The blend containing 40 wt % EPDM showed partial miscibility. The dispersed EPDM phase suppressed the glass‐transition temperature of the matrix phase. The dynamic mechanical response of rubbery region was dominated by SBR in the EPDM–SBR blend. The morphology of the blend was studied by means of scanning electron microscopy. The blend containing 80 wt % EPDM had small domains of SBR particles dispersed uniformly throughout the EPDM matrix, which helped to toughen the matrix and prevent crack propagation; this led to enhanced blend compatibility. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Mill processability of brominated isobutylene‐co‐paramethylstyrene and its blends with EPDM

Milling behavior of brominated isobutylene‐co‐paramethylstyrene (BIMS) and its blends with ethylene propylene diene terpolymer (EPDM) rubber, was investigated over a range of temperatures and friction ratios in a drop mill operation. BIMS showed striking changes, that is, from a loose nervy band to a tight elastic band, as the temperature of the rolls was increased from 30°C to 90°C. For EPDM a loose band was observed at all temperatures and friction ratios studied. For the blends of BIMS and EPDM, the milling behavior changed from a tight elastic band to a loose bagging band on increasing the EPDM content. The critical nip gap (CNG), at which the front‐to‐back roll (F–B) transition occurred, was also measured. BIMS showed a much higher value of CNG than that of EPDM, indicating that the former had a significantly higher tendency for F–B transition than the latter material. For different blends of BIMS and EPDM, the CNG decreased on increasing the EPDM content, indicating a decrease in the tendency for F–B transition. The results were explained in terms of the rubber‐to‐metal adhesion and the viscosity of the polymers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1483–1494, 2001     

Influence of the phase morphology on the molecular orientation at the crack tips in rubber‐modified nylon 6: A micro Fourier transform infrared study

Despite extensive efforts to understand the toughening mechanism of rubber‐modified semicrystalline polymers, the plastic deformation event at the crack tips with an extreme deformation gradient and its correlation with phase morphology is, thus far, poorly understood. In this study, micro Fourier transform infrared measurements were adopted to give direct evidence of plastic deformation at the crack tips by the molecular orientation in nylon 6/ethylene–propylene–diene terpolymer (EPDM) blends with a distinct phase morphology. Significant plastic deformation ahead of the crack tips, manifested by a high molecular orientation, was observed in the compatibilized nylon 6/EPDM blends with fine rubber particles. Moreover, the increased transverse crack‐propagation resistance due to high molecular orientation dramatically extended the plastic deformation into adjacent regions around the crack tips; this was responsible for enhanced energy dissipation during the fracture process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Macromolecular modification of EPDM: Wettability,miscibility, and morphology study

The present investigation deals with studies on wettability, miscibility, and morphology of the macromolecularly modified EPDM. Two different maleated EPDM rubbers (grafted rubber) were chosen (0.5 and 1% maleation) for such modification and they were used in various proportions. Wettability of the rubber substrate, as observed from dynamic contact angle measurement, was improved using these grafted rubbers. Results of X‐ray photoelectron spectroscopy showed an increase in oxygen level with higher levels of grafted rubber in the blends. Morphology study by transmission electron microscopy showed a smaller domain size for the blend with higher maleic anhydride content in the grafted rubber. The viscosity versus blend ratio results showed a negative deviation behavior for blends with 1% grafted rubber, whereas a positive negative deviation behavior was observed in blends with 0.5% grafted EPDM. As the strength of interaction increased, the glass transition shifted to a higher temperature. All blends were heterogeneous, as indicated by different degrees of dispersion. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2647–2661, 2001     

Influences of trans‐polyoctylene rubber on the physical properties and phase morphology of natural rubber/acrylonitrile–butadiene rubber blends

The influence of trans‐polyoctylene rubber (TOR) on the mechanical properties, glass‐transition behavior, and phase morphology of natural rubber (NR)/acrylonitrile–butadiene rubber (NBR) blends was investigated. With an increased TOR level, hardness, tensile modulus, and resilience increased, whereas tensile strength and elongation at break tremendously decreased. According to differential scanning calorimetry and dynamic mechanical analysis, there were two distinct glass‐transition temperatures for a 50/50 NR/NBR blend, indicating the strongly incompatible nature of the blend. When the TOR level was increased, the glass transition of NBR was strongly suppressed. NBR droplets of a few micrometers were uniformly dispersed in the continuous NR phases in the NR/NBR blends. When TOR was added to a 50/50 NR/NBR blend, TOR tended to be located in the NR phase and in some cases was positioned at the interfaces between the NBR and NR phases. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 125–134, 2002     

Fabrication of polypropylene blends with excellent low‐temperature toughness and balanced toughness‐rigidity by a combination of EPR and SEEPS

To overcome serious rigidity depression of rubber‐toughened plastics and fabricate a rigidity‐toughness balanced thermoplastic, a combination of styrene‐[ethylene‐(ethylene‐propylene)]‐styrene block copolymer (SEEPS) and ethylene‐propylene rubber (EPR) was used to toughen polypropylene. The dynamic mechanical properties, crystallization and melting behavior, and mechanical properties of polypropylene (PP)/EPR/SEEPS blends were studied in detail. The results show that the combination of SEEPS and EPR can achieve the tremendous improvement of low‐temperature toughness without significant strength and rigidity loss. Dynamic mechanical properties and phase morphology results demonstrate that there is a good interfacial strength and increased loss of compound rubber phase comprised of EPR component and EP domain of SEEPS. Compared with PP/EPR binary blends, although neither glass transition temperature (T_g) of the rubber phase nor T_g of PP matrix in PP/EPR/SEEPS blends decreases, the brittle‐tough transition temperature (T_bd) of PP/EPR/SEEPS blends decreases, indicating that the increased interfacial interaction between PP matrix and compound rubber phase is also an effective approach to decrease T_bd of the blends so as to improve low‐temperature toughness. The balance between rigidity and toughness of PP/EPR/SEEPS blends is ascribed to the synergistic effect of EPR and SEEPS on toughening PP. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45714.     

Synergetic toughness and morphology of poly(propylene)/nylon 11/maleated ethylene‐propylene diene copolymer blends

Polypropylene (PP)/nylon 11/maleated ethylene‐propylene‐diene rubber (EPDM‐g‐MAH) ternary polymer blends were prepared via melt blending in a corotating twin‐screw extruder. The effect of nylon 11 and EPDM‐g‐MAH on the phase morphology and mechanical properties was investigated. Scanning electron microscopy observation revealed that there was apparent phase separation for PP/EPDM‐g‐MAH binary blends at the level of 10 wt % maleated elastomer. For the PP/nylon 11/EPDM‐g‐MAH ternary blends, the dispersed phase morphology of the maleated elastomer was hardly affected by the addition of nylon 11, whereas the reduced dispersed phase domains of nylon 11 were observed with the increasing maleated elastomer loading. Furthermore, a core‐shell structure, in which nylon 11 as a rigid core was surrounded by a soft EPDM‐g‐MAH shell, was formed in the case of 10 wt % nylon 11 and higher EPDM‐g‐MAH concentration. In general, the results of mechanical property measurement showed that the ternary blends exhibited inferior tensile strength in comparison with the PP matrix, but superior toughness. Especially low‐temperature impact strength was obtained. The toughening mechanism was discussed with reference to the phase morphology. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Influence of the rubbery phase on the crystallinity and thermomechanical properties of poly(3‐hydroxybutyrate)/elastomer blends

Poly(3‐hydroxybutyrate) (PHB) is a very promising biopolymer. In order to improve its processability and decrease its brittleness, PHB/elastomer blends can be prepared. In the work reported, the effect of the addition of a rubbery phase, i.e. ethylene–propylene–diene terpolymer (EPDM) or poly(vinyl butyral) (PVB), on the properties of PHB was studied. The effects of rubber type and of changing the PHB/elastomer blend processing method on the crystallinity and physical properties of the blends were also investigated. For blends based on PHB, the main role of EPDM is its nucleating effect evidenced by a decrease of crystallization temperature and an increase of crystallinity with increasing EPDM content regardless of the processing route. While EPDM has a weak effect on PHB glass transition temperature, PVB induces a marked decrease of this temperature thank to its plasticizer that swells the PHB amorphous phase. A promising solution to improve the mechanical properties of PHB seems to be the melt‐processing of PHB with both plasticizer and EPDM. In fact, the plasticizer is more efficient than the elastomer in decreasing the PHB glass transition temperature and, because of the nucleating effect of EPDM, the decrease of the PHB modulus due to the plasticizer can be counterbalanced. Copyright © 2010 Society of Chemical Industry     

Effect of dynamic crosslinking on tensile yield behavior of polypropylene/ethylene‐propylene‐diene rubber blends

Tensile yield behavior of the blends of polypropylene (PP) with ethylene‐propylene‐diene rubber (EPDM) is studied in blend composition range 0–40 wt % EPDM rubber. These blends were prepared in a laboratory internal mixer by simultaneous blending and dynamic vulcanization. Vulcanization was performed with dimethylol phenolic resin. For comparison, unvulcanized PP/EPDM blends were also prepared. In comparison to the unvulcanized blends, dynamically vulcanized blends showed higher yield stress and modulus. The increase of interfacial adhesion caused by production of three‐dimensional network is considered to be the most important factor in the improvement. It permits the interaction of the stress concentrate zone developed at the rubber particles and causes shear yielding of the PP matrix. Systematic changes with varying blend composition were found in stress‐strain behavior in the yield region, viz., in yield stress, yield strain, width of yield peak, and work of yield. Analysis of yield stress data on the basis of the various expressions of first power and two‐thirds power laws of blend compositions dependence and the porosity model led to consistent results from all expression about the variation of stress concentration effect in both unvulcanized and vulcanized blend systems. Shapes and sizes of dispersed rubber phase (EPDM) domains at various blend compositions were studied by scanning electron microscopy. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2104–2121, 2000     

Phase morphology and thermomechanical analysis of poly(styrene‐co‐acrylonitrile)/ethylene–propylene–diene monomer blends: Uncompatibilized and reactively compatibilized blends with two mixing sequences

The phase morphology developing in immiscible poly(styrene‐co‐acrylonitrile) (SAN)/ethylene–propylene–diene monomer (EPDM) blends was studied with an in situ reactively generated SAN‐g‐EPDM compatibilizer through the introduction of a suitably chosen polymer additive (maleic anhydride) and 2,5‐dimethyl‐2,5‐di‐(t‐butyl peroxy) hexane (Luperox) and dicumyl peroxide as initiators during melt blending. Special attention was paid to the experimental conditions required for changing the droplet morphology for the dispersed phase. Two different mixing sequences (simple and two‐step) were used. The product of two‐step blending was a major phase surrounded by rubber particles; these rubber particles contained the occluded matrix phase. Depending on the mixing sequence, this particular phase morphology could be forced or could occur spontaneously. The composition was stabilized by the formation of the SAN‐g‐EPDM copolymer between the elastomer and addition polymer, which was characterized with Fourier transform infrared. As for the two initiators, the blends with Luperox showed better mechanical properties. Scanning electron microscopy studies revealed good compatibility for the SAN/EPDM blends produced by two‐step blending with this initiator. Dynamic mechanical thermal analysis studies showed that the two‐step‐prepared blend with Luperox had the best compatibility. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Optimization of accelerators on curing characteristics,tensile, and dynamic mechanical properties of (natural rubber)/(recycled ethylene‐propylene‐diene‐monomer) blends

The migration of sulfur from natural rubber (NR) compound to the ground waste ethylene‐propylene‐diene monomer (EPDM) rubber phase may have caused the cure incompatibility between these two rubbers. Optimization of accelerators had been adopted to overcome the cure incompatibility in NR/(R‐EPDM) blends as well as to get increased curative distribution. In this study, blends of NR and R‐EPDM were prepared. The effect of accelerator type on curing characteristics, tensile properties, and dynamic mechanical properties of 70/30/NR/(R‐EPDM) blend was investigated. Four types of commercial accelerators were selected [ie, N‐tert‐butyl‐2‐benzothiazyl‐sulphonamide , N‐cyclohexyl‐benzothiazyl‐sulfenamide (CBS), tetramethylthiuram disulfide, and 2‐mercaptobenzothiazol]. It was found that the tensile strength of the blends cured in the presence of CBS was relatively higher than the other three accelerators. Scanning electron micrographs of CBS‐cured NR/(R‐EPDM) blends exhibited more roughness and cracking path, indicating that higher energy was required toward the fractured surface. The high crosslinking density observed from the swelling method could be verified from the storage modulus (E′) and damping factor (tan δ) where (tetramethylthiuram disulfide)‐cured NR/(R‐EPDM) blends provided a predominant degree of crosslinking followed by N‐tert‐butyl‐2‐benzothiazyl‐sulphonamide , CBS, and 2‐mercaptobenzothiazol, respectively. J. VINYL ADDIT. TECHNOL., 21:79–88, 2015. © 2014 Society of Plastics Engineers