Dielectric and mechanical properties of polystyrene/acrylonitrile–butadiene rubber blends

The dielectric and mechanical properties of polystyrene(PS)/acrylonitrile–butadiene rubber (NBR) blends were studied with the aim of improving the insulation properties of NBR. Compatibility investigations, performed with viscosity and dielectric methods and confirmed with the calculated heat of mixing, indicated that such blends were incompatible. To overcome the problem of phase separation between NBR and PS, we chose epoxidized soya bean oil to act as a compatibilizer and added 3% to the blends under investigation. This led to the conclusion that a sample containing 10% PS (either pure or scrap) possessed the most suitable electrical and mechanical properties. For this reason, the sample was chosen for studying the effect of the addition of three types of fillers (quartz, talc, and calcium carbonate) in increasing quantities (up to 80 phr) on the dielectric and mechanical properties. The variation of the dielectric properties with temperature (20–60°C) was also investigated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 540–552, 2002     

Impact of blend ratio on the properties of graphene oxide‐filled carboxylated acrylonitrile–butadiene rubber/styrene–butadiene rubber blends

Carboxylated acrylonitrile–butadiene rubber (XNBR) and styrene–butadiene rubber (SBR) composites with 3 phr (parts per hundred rubber) graphene oxide (GO) were prepared using a latex mixing method. Effects of XNBR/SBR blend ratios on the mechanical properties, thermal conductivity, solvent resistance and thermal stability of the XNBR/SBR/GO nanocomposites were studied. The tensile strength, tear strength, thermal conductivity and solvent resistance of the XNBR/SBR/GO (75/25/3) nanocomposite were significantly increased by 86, 96, 12 and 21%, respectively, compared to those of the XNBR/SBR (75/25) blend. The thermal stability of the nanocomposite was significantly enhanced; in other words, the temperature for 5% weight loss and the temperature of the maximal rate of degradation process were increased by 26.01 and 14.97 °C, respectively. Theoretical analysis and dynamic mechanical analysis showed that the GO tended to locate in the XNBR phase, which led to better properties of the XNBR/SBR/GO (75/25/3) nanocomposite. © 2017 Society of Chemical Industry     

Dual crosslinking of carboxylated nitrile butadiene rubber latex employing the thiol‐ene photoreaction

At present, the most common used crosslinking process for carboxylated nitrile butadiene rubber (XNBR) latex is an accelerated sulfur curing system with zinc oxide. To avoid allergenic reactions related to residual accelerator levels in dipped XNBR latex articles such as medical gloves, a dual curing process has been developed combining thermal and photochemical crosslinking reactions. The two‐step procedure involves the formation of covalent and ionic bonds to ensure good mechanical properties of the final products. The photochemical thiol‐ene reaction is used to generate covalent crosslinks between the remaining C?C double bonds of the butadiene units whereas the carboxylic moieties are conventionally cured with divalent metal oxides (ZnO) under elevated temperature (formation of ionic crosslinks). The photochemical curing step is carried out both in the latex phase using a falling film photoreactor (prevulcanization) as well as in the solid phase by UV irradiation of dried XNBR films (postvulcanization). The mechanical properties and crosslink densities of the cured XNBR films are determined and the influence of selected curing parameters is assessed. The results give evidence that a combined approach of thermal prevulcanization and photochemical postvulcanization makes the production of latex articles (e.g., gloves) with tailored properties and good skin compatibility feasible. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of filler surface treatment on mechanical properties and thermal properties of single and hybrid filler–filled PP composites

The influence of two types of surface treatments (aminosilane and Lica‐12) on the mechanical and thermal properties of polypropylene (PP) filled with single and hybrid filler (silica and mica) was studied. An improvement in tensile properties and impact strength was found for both treatments compared to those of untreated composites. However, the filler with silane coupling agent showed better improvement compared to the filler with Lica‐12 coupling agent. This was due to better adhesion between filler and matrix. Thermal analysis indicates that surface treatments increased the nucleating ability of filler, but decreased the coefficient of thermal expansion of PP composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Crosslinking of unfilled carboxylated nitrile rubber with different systems: Influence on properties

The presence of two functional groups, nitrile and carboxyl, in carboxylated nitrile rubber allows it to be crosslinked with different agents. In this study, we examined the influence of different crosslinking agents on the properties of unfilled carboxylated nitrile rubber. Significant differences were found when different crosslinking agents were used, as shown in the vulcanization curves, especially in the variation of the viscous component with the reaction time. The reaction rate was highest when organic peroxide was used, and it was lowest when metallic peroxide or copper sulfate was used. When the crosslinking agents led to the formation of ionic bonds (metallic oxide and metallic peroxide), the carboxylic groups ? COOH had a greater participation in the crosslinking. However, when copper sulfate was used, coordination bonds were formed, and the main contribution was due to the nitrile groups. Tensile strength, tear strength, and abrasion properties were superior when the crosslinking systems used led to the formation of ionic bonds. On the contrary, the compression set was optimum when covalent bonds were formed. Copper sulfate behaved as an intermediate between the two previous situations. The mechanodynamic response of the compounds also depended on the crosslinking agent used. The correlation between crosslink density by swelling in dichloromethane, maximum damping temperature by dynamic measurements, and glass‐transition temperature by differential scanning calorimetry had to be explained in terms of the crosslink type. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Keratin as a filler for carboxylated acrylonitrile‐butadiene rubber XNBR

The presented investigations concern the distribution and characterization of keratin waste, derived from the processes of cattle skins, and its use as a filler for carboxylated acrylonitrile‐butadiene rubber XNBR. The recovered keratin improves mechanical proprieties such as tensile strength, hardness, resistance to fuel and oil. The addition of keratin in a quantity of five parts per hundred rubber (XNBR) increases the crosslinking density of composites, as testified by the formed ion nodes and the existing mono and disulphide bonds. Electric conductance and water absorption increased with time for elastomers filled with protein. Therefore these composites are biodegradable after their period of use. As a result hydrophilic–hydrophobic protein–elastomeric composites will have usable properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Mechanical and viscoelastic behavior of natural rubber and carboxylated styrene‐butadiene rubber latex blends

The morphology, mechanical and viscoelastic behavior of latex blends of unvulcanized natural rubber (NR) with carboxylated styrene‐butadiene rubber (XSBR) were investigated, with special reference to the effect of the blend ratio, temperature, and frequency. Mechanical properties like tensile strength, modulus, and elongation at break were also studied. As the XSBR content increased, the tensile strength increased up to a 50:50 NR/XSBR ratio and then decreased as a result of the self‐curing nature of XSBR. The dynamic mechanical properties of these latex blends were analyzed for loss tangent, storage modulus, and loss modulus. The entire blend yielded two glass‐transition temperatures, which corresponded to the transitions of individual components, indicating that the system was immiscible. To determine the change in modulus with time, a master curve of 50:50 NR/XSBR blends was plotted. Time–temperature superposition and Cole–Cole analysis were done to understand the phase behavior of the latex blends. The experimental and theoretical values of storage modulus of blends were compared using the Kerner and Halpin–Tsai models. With the help of optical micrographs, attempts were made to correlate the morphology and viscoelastic behavior of these blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2639–2648, 2003     

Possible use of ultra‐fine acrylonitrile butadiene rubber powder as filler in natural rubber vulcanizates

Possible use of ultra‐fine acrylonitrile butadiene rubber powder (UFNBRP) as a filler for natural rubber (NR) was investigated. The UFNBRP was added into NR at various concentrations, and the compound properties were determined. It is found that, with increasing UFNBRP loading, the compound viscosity is increased, whereas both scorch time and optimum curing time are significantly reduced. The results also reveal that UFNBRP has negative effect not only on crosslink density but also on most mechanical properties of the vulcanizate, such as tensile strength, tear strength, compression set, and abrasion resistance. The deterioration of these mechanical properties is thought to arise mainly from the combined effect of large phase size of the dispersed UFNBRP and low interfacial adhesion taking place from the polarity difference between UFNBRP and NR. Interestingly, it is found that, after aging, UFNBRP could promote postcuring phenomenon leading to increases of both relative 100% modulus and relative tensile strength. Oil resistance is also found to improve considerably with increasing UFNBRP loading. This improvement is mainly attributed to the dilution effect, i.e., the higher the UFNBRP loading, the lower the NR portion and, thus, the greater the oil resistance of the vulcanizate. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Mechanical properties and network structure of phenol resin crosslinked hydrogenated acrylonitrile‐butadiene rubber

The tough and stretchable crosslinked hydrogenated acrylonitrile–butadiene rubber (HNBR) could be prepared by resol type phenol resin as a crosslinker. The mechanical properties and the network structure of the phenol resin crosslinked HNBR were investigated by comparing with those of the peroxide crosslinked HNBR having the higher crosslink density and the heterogeneous network structure. The elastic modulus and the strain at break of the phenol resin crosslinked HNBR were much higher than those of the peroxide one. The residual strain was below 20 % after stretching up to 650 % and then releasing from the cramps. Since the crosslink density is low, the high elastic modulus and the good recovery deformation are attributed to the stiffness and rigidity of the crosslink junctions obtained by phenol resin. Small‐angle X‐ray scattering measurements revealed that the network structure is spatially homogeneous and the results of the wide angle X‐ray diffraction indicate that the strain‐induced crystallization is suppressed, which enable the longer elongation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Electron‐beam curing of hydrogenated acrylonitrile–butadiene rubber

The electron‐beam‐induced crosslinking of hydrogenated acrylonitrile–butadiene rubber (HNBR) was investigated. HNBR sheets were exposed to electron‐beam irradiation in air at a room temperature of 25 ± 2°C over a dose range of 0–20 Mrad. An attempt was made to correlate the structure of the irradiated rubber with the properties. The ratio of chain scission to crosslinking and the gelation dose were determined by a method proposed elsewhere. The gel content and dynamic storage modulus increased with the radiation dose. Fourier transform infrared studies revealed the formation of double bonds and carbonyl and ether groups. These observations were further supported by a thermogravimetric analysis of the carbonaceous residue of irradiated HNBR. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 648–651, 2005     

Structural morphology and properties of star styrene–isoprene–butadiene rubber and natural rubber/star styrene–butadiene rubber blends

Star styrene–isoprene–butadiene rubber (SIBR) was synthesized with a new kind of star anionic initiator made from naphthalene lithium and an SnCl₄ coupled agent. The relationship between the structure and properties of star SIBR was studied. Star block styrene–isoprene–butadiene rubber (SB‐SIBR), having low hysteresis, high road‐hugging, and excellent mechanical properties, was closer to meeting the overall performance requirements of ideal tire‐tread rubber according to a comparison of the morphology and various properties of SB‐SIBR with those of star random SIBR and natural rubber/star styrene–butadiene rubber blends. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 336–341, 2004     

Enhancing the mechanical properties of styrene–butadiene rubber by optimizing the chemical bonding between silanized silica nanofiller and the rubber

The reinforcing effect of a large amount of synthetic precipitated amorphous white silica nanofiller on the mechanical properties of styrene–butadiene rubber was studied. The silica surfaces were pretreated with bis(3‐triethoxysilylpropyl)tetrasulfane (TESPT). TESPT is a bifunctional organosilane that chemically adheres silica to rubber and also prevents silica from interfering with the reaction mechanism of sulfur cure in the rubber. The silica particles were fully dispersed in the rubber and the chemical bonding between the rubber and filler was optimized by the incorporation of accelerator and activator in the rubber. This study showed that the mechanical properties of the rubber vulcanizate improved substantially when the filler was added. The addition of elemental sulfur affected the rubber properties, although there was no overall advantage, as some properties improved and others deteriorated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Dynamic mechanical properties of styrene‐butadiene rubber vulcanizate filled with electron beam modified surface‐treated dual‐phase filler

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     

Nanomodified fillers in chloroprene‐rubber‐compatibilized natural rubber/acrylonitrile–butadiene rubber blends

Because of the structural dissimilarity, natural rubber (NR) and acrylonitrile–butadiene rubber (NBR) are immiscible, and compatibilizers are used during their blending. Neoprene or chloroprene rubber (CR) has a polar chlorine part and a nonpolar hydrocarbon part. Also, it has many advantageous properties, such as oil resistance, toughness, a dynamic flex life, and adhesion capacity. Hence, it is not less scientific to use CR as a compatibilizer in the blending of NBR with NR. Because many fewer studies on the use of neoprene as a compatibilizer in NR–NBR blend preparation are available, efforts were made to prepare 20:80 NR–NBR blends with CR with the aim of studying the effect of poly(ethylene oxide) (PEO)‐coated nano calcium silicate along with nano N‐benzylimine aminothioformamide and stearic acid coated nano zinc oxide in the sulfur vulcanization of the blends. The optimum dosage of the compatibilizer was derived by the determination of the tensile properties, tear resistance, abrasion resistance, compressions set, and swelling values. The tensile strength, tear resistance, and abrasion resistance of the gum vulcanizates of the blend were improved by the compatibilizing action of CR up to 5 parts per hundred parts of rubber (phr). In the case of the filled vulcanizates, the tear resistance, 300% modulus, hardness, and abrasion resistance increased with increasing dosage of nano calcium silicate. The elongation at break percentage decreased as expected when there was an increase in the modulus. Scanning electron microscopy was used to study the phase morphology of the blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Mechanical and aging properties of cross‐linked ethylene propylene diene rubber / styrene butadiene rubber blends

The mechanical properties and aging characteristics of blends of ethylene propylene diene monomer (EPDM) rubber and styrene butadiene rubber (SBR) were investigated with special reference to the effect of blend ratio and cross‐linking systems. Among the blends, the one with 80/20 EPDM/SBR has been found to exhibit the highest tensile, tear, and abrasion properties at ambient temperature. The observed changes in the mechanical properties of the blends have been correlated with the phase morphology, as attested by scanning electron micrographs (SEMs). The effects of three different cure systems, namely, sulfur (S), dicumyl peroxide (DCP), and a mixed system consisting of sulfur and peroxide (mixed) on the blend properties also were studied. The stress‐strain behavior, tensile strength, elongation at break, and tear strength of the blends were found to be better for the mixed system. The influence of fillers such as high‐abrasion furnace (HAF) black, general‐purpose furnace (GPF) black, silica, and clay on the mechanical properties of 90/10 EPDM/SBR blend was examined. The ozone and water aging studies also were conducted on the sulfur cured blends, to supplement the results from the mechanical properties investigation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2606–2621, 2004     

Effect of different types of carbon black on the mechanical and acoustic properties of ethylene–propylene–diene rubber

The effects of the incorporation of different types of carbon black as fillers on some selected physical and mechanical properties of ethylene–propylene–diene rubber (EPDM) based compounds were studied with the results of density, ultrasonic wave velocity, and tensile measurements. Ultrasonic wave velocities (both longitudinal and shear) were measured at frequencies up to 4 MHz at room temperature. The density, ultrasonic attenuation coefficient, and tensile strength results showed that rubber mixes containing general‐purpose furnace (GPF) black at a concentration of 25 phr had the best physical and mechanical properties. These results were interpreted to be due to the better compatibility of GPF black, which, because of its particle size and structure, filled the interstitial spaces in EPDM and provided better reinforcement of the elastomer. The use of a nondestructive technique such as ultrasonic measurement presents a new possibility for testing rubber and plastic products more efficiently. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of acrylic acid on the properties of recycled poly(vinyl chloride)/acrylonitrile–butadiene rubber blends

The effect of acrylic acid (AAc) on the torque, stabilization torque, mechanical energy, swelling behavior, mechanical properties, thermal stability, and morphological characteristics of recycled poly(vinyl chloride)/acrylonitrile–butadiene rubber (PVCr/NBR) blends was studied. The blends were melt mixed at a temperature of 150°C and rotor speed of 50 rpm. AAc was used to improve the compatibility of PVCr/NBR blends. Virgin PVCv/NBR blends were prepared to provide a comparison. It was found that PVCr/NBR + AAc blends exhibit higher stabilization torque, mechanical energy, stress at peak, and stress at 100% elongation, but lower elongation at break and swelling index than those of PVCr/NBR and PVCv/NBR blends. SEM study of the tensile fracture surfaces of the blends indicated that the presence of AAc increased the interfacial interaction between PVCr and NBR phases, thus improving the compatibility between PVCr and NBR phases. However, thermal gravimetry analysis of the blends showed that the presence of AAc decreased the thermal stability of PVCr/NBR blends. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2181–2191, 2005     

Effect of a natural magnesium silicate treated with a new coupling agent on the properties of ethylene–propylene–diene rubber compounds

The behavior of sepiolite (magnesium silicate with a microfibrillar morphology) as a filler in ethylene–propylene–diene compounds was studied. A new coupling agent, meta‐isopropenyl dimethyl benzyl isocyanate, was used. The effect of the filler modified by meta‐isopropenyl dimethyl benzyl isocyanate on the physical properties was improved with respect to other fillers and commercial silane coupling agents under the same conditions. In addition to a smoother surface, the flow behavior of compounds filled with sepiolite, on account of its fibrous morphology, was better than that obtained with other fillers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1489–1493, 2004     

Mechanical and functional properties of composites based on graphite and carboxylated acrylonitrile butadiene rubber

In this study, carboxylated acrylonitrile butadiene rubber (xNBR)/expanded graphite (EG) nanocomposites were prepared with a latex compounding technique by ultrasonic stirring. The dispersion of EG in the xNBR matrix was investigated with transmission electron microscopy, scanning electron microscopy, and X‐ray diffraction analysis. EG could be exfoliated into lots of nanosheets dispersing in the xNBR matrix. More EG loading resulted in the presence of a few incompletely exfoliated agglomerates. The mechanical properties (hardness, tensile modulus, and tensile strength) of the xNBR/EG composites were determined. Dynamic mechanical thermal analysis was also performed, and it showed that the nanosheets of EG somewhat immobilized the motion of rubber macromolecular chains and led to the shifting and broadening of the tan δ peak toward higher temperatures. Many other functional properties of EG‐filled xNBR composites were studied, and it was established that the composites had excellent electrical conductivity as well as gas‐barrier and wear properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Amelioration of acrylonitrile–butadiene copolymer properties using natural rubber graft p‐aminophenol

A two‐roll mill machine was used for the grafting of p‐aminophenol (pAP) onto natural rubber (NR). The prepared NR graft p‐aminphenol (NR‐g‐pAP) was characterized by ¹H NMR and IR spectroscopy techniques. The goal of this article is to study the effect of commercial antioxidants, N‐phenyl‐N′‐(1,3‐dimethylbutyl)‐p‐phenylenediamine (6PPD) and N‐phenyl‐N′‐isopropyl‐p‐phenylenediamine (IPPD), and the prepared NR‐g‐pAP, on the mechanical properties of acrylonitrile–butadiene (NBR) vulcanizates, the fluid compatibility of NBR vulcanizates, the hydraulic brake and clutch fluid dot, the diffusion out for NBR vulcanizate components, and the compression recovery of NBR vulcanizates. This study indicates that the NBR copolymer vulcanizate which contains the prepared NR‐g‐pAP has good protection against mechanical stress and the diffusion out of NBR vulcanizate components. The 6PPD and the prepared NR‐g‐pAP ameliorates the fluid compatibility of the oil seals, which is based on NBR as elastomer, and the hydraulic brake and clutch fluid dot. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 2007