A SAXS and swelling study of cured natural rubber/styrene–butadiene rubber blends

A small‐angle X‐ray scattering (SAXS) and swelling study of natural rubber and styrene–butadiene rubber blends (NR/SBR) is presented. To this aim, specimens of NR and SBR and blends with 75/25, 50/50, and 25/75 NR/SBR ratios (in phr) were prepared at a cure temperature of 433 K and the optimum cure time (t₁₀₀). This time was obtained from rheometer torque curves. The system of cure used in the samples was sulfur/n‐t‐butyl‐2‐benzothiazole sulfenamide. From swelling tests of the cured samples, information about the molecular weight of the network chain between chemical crosslinks was obtained. For all cured compounds, in the Lorentz plots built from SAXS scattering curves, a maximum of the scattering vector q around 0.14 Å^?1 was observed. However, the q position shows a linear‐like shift toward lower values when the SBR content in the SBR/NR blend increases. In pure NR or SBR the q values show a different tendency. The results obtained are discussed in terms of the existence of different levels of vulcanization for each single phase forming the blend and the existence of a third level of vulcanization located in the interfacial NR/SBR layer. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2320–2327, 2009     

Preparation and properties of graded styrene‐butadiene rubber vulcanizates

Styrene‐butadiene rubber (SBR) vulcanizates with graded network‐chain densities in the thickness direction were prepared by layering and heat pressing the compounding sheets. The effect of the gradient of network‐chain density on the mechanical properties of the graded rubber vulcanizates was investigated in comparison with those of SBR vulcanizates that were prepared from the homogeneous compounding sheets. The matrix with a high network‐chain density exclusively affected the mechanical properties of the graded rubber vulcanizates when the gradient was given in the thickness direction. © 2002 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 358–364, 2002; DOI 10.1002/polb.10096     

Preparation and properties of nanocomposites based on acrylonitrile–butadiene rubber,styrene–butadiene rubber,and polybutadiene rubber

Nanocomposites were prepared with different grades of nitrile rubber with acrylonitrile contents of 19, 34, and 50%, with styrene–butadiene rubber (23% styrene content), and with polybutadiene rubber with Na‐montmorillonite clay. The clay was modified with stearyl amine and was characterized by X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). The XRD studies showed an increase in the gallery gap upon the modification of the filler by stearyl amine. The intercalation of the amine chains into the clay gallery gap was confirmed by the presence of some extra peaks (2928, 2846, and 1553 cm^?1) in the FTIR spectra. The clay–rubber nanocomposites were characterized by TEM and XRD. The mechanical properties were studied for all the compositions. An improvement in the mechanical properties with the degree of filler loading up to a certain level was observed. The changes in the mechanical properties, with changes in the nature and polarity of the rubbers, were explained with the help of XRD and TEM results. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1573–1585, 2004     

Analysis of structure–properties relationship in nitrile‐butadiene rubber/phenolic resin/organoclay ternary nanocomposites using simple model system

The present study deals with the structure–property relationship of organoclay (OC) filled nanocomposites based on rubber blend comprising of nitrile‐butadiene rubber (NBR) and phenolic resin (PH). To obtain a better insight into the characteristics of the NBR/PH/OC hybrid system, a simple model system consisting of NBR/OC nanocomposites is also taken into consideration. A series of NBR/OC and NBR/PH/OC nanocomposites containing a wide range of OC concentrations (2.5–30 phr) are prepared by using traditional open two‐roll mill. Structural analysis performed by X‐ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM) exhibits mixed exfoliated and intercalated morphology at low OC content, below 7.5 phr, and a well‐ordered intercalated morphology at higher OC loading. It is shown that the dispersion of OC is also influenced by mixing time and order of mixing of components. Analysis of the cure characteristics, mechanical, and thermal properties of both the NBR/OC and NBR/PH/OC nanocomposites reveals that the OC is dispersed mainly in the NBR continuous phase, even though some is likely localized in the rubber–resin interface. Copyright © 2009 John Wiley & Sons, Ltd.     

共混硫化丁腈橡胶-氯丁橡胶的物理性能

将丁腈橡胶(NBR)和氯丁橡胶(CR)按不同质量分数共混并硫化,研究了硫化橡胶在自然环境、热空气老化、热油老化等条件下的物理性能,并测定了硫化橡胶与镀铜钢丝的粘合性能.结果表明,随着CR质量分数的增大,混炼胶的焦烧时间逐渐缩短.经热空气老化后,NBR的硬度增加幅度比CR的硬度增加幅度大,拉断强度降低幅度则比CR的小得多.此外,NBR的耐油性能优于CR.就物理性能以及与镀铜钢丝的粘合性能而言,单一NBR和单一CR优于共混NBR/CR.     

Effect of electron beam irradiation on mechanical and thermal properties of waste polyamide copolymer blended with nitrile‐butadiene rubber

In the present study, the effect of electron beam irradiation on the morphological, thermal, and mechanical properties of waste polyamide copolymer (WPA‐66/6) blended with different contents of acrylonitrile butadiene rubber (NBR) were studied. The prepared blends were subjected to irradiation doses up to 150 kGy and the structural modifications were discussed; non‐irradiated blends were used as control. Mechanical properties, namely, tensile strength (TS), yield strength, elongation at break, and hardness, were followed up as functions of irradiation dose and degree of loading with rubber content. On the other hand, the influence of irradiation dose on the thermal parameters, melting temperature, heat of fusion, ΔH_m of the recycled PA copolymer, and its blend with NBR were also investigated. Copyright © 2009 John Wiley & Sons, Ltd.     

Morphology and mechanical and viscoelastic properties of natural rubber and styrene butadiene rubber latex blends

The morphology and mechanical and viscoelastic properties of a series of blends of natural rubber (NR) and styrene butadiene rubber (SBR) latex blends were studied in the uncrosslinked and crosslinked state. The morphology of the NR/SBR blends was analyzed using a scanning electron microscope. The morphology of the blends indicated a two phase structure in which SBR is dispersed as domains in the continuous NR matrix when its content is less than 50%. A cocontinuous morphology was obtained at a 50/50 NR/SBR ratio and phase inversion was seen beyond 50% SBR when NR formed the dispersed phase. The mechanical properties of the blends were studied with special reference to the effect of the blend ratio, surface active agents, vulcanizing system, and time for prevulcanization. As the NR content and time of prevulcanization increased, the mechanical properties such as the tensile strength, modulus, elongation at break, and hardness increased. This was due to the increased degree of crosslinking that leads to the strengthening of the 3‐dimensional network. In most cases the tear strength values increased as the prevulcanization time increased. The mechanical data were compared with theoretical predictions. The effects of the blend ratio and prevulcanization on the dynamic mechanical properties of the blends were investigated at different temperatures and frequencies. All the blends showed two distinct glass‐transition temperatures, indicating that the system is immiscible. It was also found that the glass‐transition temperatures of vulcanized blends are higher than those of unvulcanized blends. The time–temperature superposition and Cole–Cole analysis were made to understand the phase behavior of the blends. The tensile and tear fracture surfaces were examined by a scanning electron microscope to gain an insight into the failure mechanism. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2189–2211, 2000     

TG-MS analysis of nitrile butadiene rubber blends (NBR/PVC)

Blends of nitrile butadiene rubber (NBR) with polyvinyl chloride (PVC) are widely used in products such as hoses and seals. As part of a project that uses NBR/PVC blends for manufacturing forest fire hoses, blends of NBR/PVC with various inorganic fillers, such as Mg(OH)₂, china clay (organic modified kaolin) and nano clay (organic modified bentonite) were studied by TG-MS. No significant changes were observed to the type of the polymers’ decomposition products, compared to that of NBR/PVC blend without additives. The most remarkable change was the absence of HCl from decomposition products in the presence of the Mg(OH)₂ additive.     

Thermal properties in cured natural rubber/styrene butadiene rubber blends

Blends of natural rubber (NR) and styrene butadiene rubber (SBR) were prepared with sulfur and n-t-butyl-2-benzothiazole sulfonamide (TBBS) as accelerator, varying the amount of each polymer in the blend. Samples were analysed by rheometer curing at 433 K until their maximum torque was reached. The miscibility among the constituent polymers of the cured compounds was studied in a broad range of temperatures by means of differential scanning calorimetry, analyzing the glass transition temperatures of the samples. The specific heat capacity of the compounds was also determined. Thermal diffusivity of the samples was measured in the temperature range from 130 to 400 K with a new device that performs measurements in vacuum. The thermal results are explained on the basis of the structure formed during the vulcanization of the samples considering the variation of the crosslink density of each phase. Finally, a serial thermal conduction model that takes into account the contribution of each phase to the thermal diffusivity was used to fit the experimental results.     

Dichlorocarbene modified butadiene rubber (DCBR): Preparation,kinetic study,and its properties in natural rubber/DCBR blend vulcanizates

Dichlorocarbene modified butadiene rubber (DCBR) was prepared via the addition of the dichlorocarbene group in the presence of 2 phase transfer agents (cetyltrimethylammonium bromide and tetraethylammonium chloride). The effects of the reaction temperature and time, amount of dichlorocarbene precursor, and the type and amount of phase transfer agent on the chlorine content were investigated. The highest chlorine content (30%) in DCBR was obtained using 0.062 mol chloroform and 0.003 mol cetyltrimethylammonium bromide at room temperature for 19 hours although 27.9% was obtained after 12 hours. The kinetics of this dichlorocarbene modification was best described by the pseudo–first order rate law with 2 rate constants. For practical applications, the DCBR with chlorine contents of 10%, 20%, or 30% were blended with natural rubber (NR) and then vulcanized using the sulfur‐curing system. Although the polarity of DCBR was increased, a good compatibility between NR and DCBR still existed, resulting in improved mechanical properties. The oil resistance, flame retardant, and ozone resistance properties of the NR/DCBR blend vulcanizates were enhanced compared to those of a NR/butadiene rubber blend vulcanizate, which was related to the amount of chlorine incorporated into the DCBR.     

Thermal characterization of nitrile butadiene rubber (NBR)/PVC blends

Summary Nitrile butadiene rubber (NBR) and NBR/PVC blends were produced using 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ) or not as antioxidant. Controlled ozone degradation was performed in several samples. Thermal, compositional and morphological analysis was performed by means of differential scanning calorimetry, thermogravimetry, chemical analysis and scanning electron microscopy. Thermogravimetry analysis shows four mass loss processes related to plastizicer, complex rubber degradation and metallic oxides and other additives. In NBR (NBR/PVC blends) the onset temperature of the first degradation process varies between 227-231°C (259-262°C) and the apparent activation energy between 26 and 36 kJ mol^-1 (36-57 kJ mol^-1), the NBR/PVC samples non degraded presents the higher thermal stability.     

Shape memory properties of dynamically vulcanized poly(lactic acid)/nitrile butadiene rubber (PLA/NBR) thermoplastic vulcanizates: The effect of ACN content in NBR

Morphology structure and interfacial interaction are crucial factors for shape memory thermoplastic vulcanizates. In this study, shape memory thermoplastic vulcanizates based on poly(lactic acid) (PLA) and nitrile butadiene rubber (NBR) were prepared through dynamic vulcanization. The influence of acrylonitrile (ACN) content on the morphology, compatibility, shape memory property, and mechanical property was investigated. A co‐continuous structure was observed. The interfacial compatibilization between PLA and NBR phases occurred, resulting in a significantly improved interface adhesion and interfacial interaction, which was confirmed by Fourier transform infrared spectroscopy. With such a novel structure, the PLA/NBR TPVs owned an excellent shape memory property and further improved with increasing ACN content of NBR, which could be explained that the cross‐linked continuous NBR phase provided a stronger recovery driving force. In the meantime, tensile strength and elongation at break of TPVs increased with increase in ACN content. It is concluded that the preparation of dynamically vulcanized thermoplastic vulcanizate with co‐continuous structure and strong interfacial adhesion is beneficial to obtain outstanding shape memory effect.     

Radiation effect on properties of carbon black filled NBR/EPDM rubber blends

Rubber blend of acrylonitrile butadiene rubber (NBR) and ethylene-propylene diene monomer (EPDM) rubber (50/50) has been loaded with increasing contents, up to 100 phr, of reinforcing filler, namely, high abrasion furnace (HAF) carbon black. Prepared composites have been subjected to gamma radiation doses up to 250 kGy to induce radiation vulcanization under atmospheric conditions. Mechanical properties, namely, tensile strength (TS), tensile modulus at 100% elongation (M₁₀₀), and hardness have been followed up as a function of irradiation dose and degree of loading with filler. On the other hand, variation of the swelling number as a physical property, as a function of same parameters, however, in car oil as well as brake oil has been undertaken. In addition, the electrical properties of prepared composites, namely, their electrical conductivity, were also evaluated. The thermal behavior of the prepared composites was also investigated. The results obtained indicate that improvement has been attained in different properties of loaded NBR/EPDM composites with respect to unloaded ones.     

Raman investigation of thermoplastic vulcanizates based on hydrogenated natural rubber/polypropylene blends

Raman spectroscopy including mapping technique appears as a powerful technique for the characterization of polymer blends like thermoplastic elastomers (TPEs) and thermoplastic vulcanizates (TPVs). The Raman spectra of polymers blends such as natural rubber/polypropylene (NR/PP) and 65% hydrogenated natural rubber/polypropylene (65%HNR/PP) were identified and the phase distribution was determined. The study was driven for the same type of blends in TPEs state and TPVs state obtained after to 2 different processes, either peroxide cure or sulfur cure. The morphology of TPEs and TPVs obtained by Raman spectroscopy were compared and confirmed using scanning electronic microscopy.Raman mapping shows that the phase morphology of NR/PP, 65%HNR/PP, were characterized as continuous rubber phase morphology of the thermoplastic elastomers (TPEs) and a fine dispersion of cross-linked rubber phase in a continuous matrix of the thermoplastic vulcanizates (TPVs). Raman spectroscopy is demonstrated to be a reference to determine the content ratio of each component in the TPVs. Moreover, Raman mapping could be used to calculate the phase size of cross-linked rubber phase dispersed in the thermoplastic vulcanizates (TPVs).     

Filler‐polymer interactions of styrene and butadiene units in silica‐filled styrene–butadiene rubber compounds

Styrene–butadiene rubber (SBR) is a copolymer of styrene and butadiene, and the butadiene unit is composed of cis‐1,4‐, trans‐1,4‐, and 1,2‐components. Filler‐polymer interactions of each component of SBR in silica‐filled SBR compounds were examined by microstructure analysis of the bound and unbound rubbers. The composition ratio of butadiene and styrene units (butadiene/styrene) of the bound rubber was higher than that of the compounded rubber. Of the butadiene units, the 1,2‐component of the bound rubber was more abundant than the cis‐1,4‐ and trans‐1,4‐components. The filler‐polymer interaction of the butadiene unit with silica was stronger than that of the styrene unit, and the interaction of the 1,2‐component was stronger as compared with the others. The butadiene–styrene ratio of the bound rubber of the compounds containing the silane coupling agent was lower than for the compounds without the silane. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 577–584, 2004     

Thermal properties of swollen butadiene-acrylonitrile rubber vulcanizates

The present paper discusses the results of assessing thermal properties of nitrile rubber, Perbunan NT 3945 and its peroxide vulcanizates, before and after their swelling in solvents such as benzene, toluene and dimethylformamide. The measurements were carried out by means of differential scanning calorimetry (DSC) and thermogravimetry (TG) under nitrogen. It has been found that a slight rise in the glass transition temperature due to the elastomer cross-linking is clearly revealed under the influence of its vulcanizates swelling in solvents whose solubility parameters considerably differ from the solubility parameters of the polymer. The thermal curves of swollen samples reveal processes resulting from polymer-solvent interactions and thermodesolvation processes, which accompany the initial stage of solvent evaporation.The authors would like to express their thanks to the Bayer company for providing free of charge samples of Perbunan NT 1845 and Perbunan 3945 which were used in this study.     

Electrically conductive acrylonitrile–butadiene rubber elastomers prepared by dopamine‐induced surface functionalization and metallization

A novel method for the preparation of electrical conductive surface silvered acrylonitrile–butadiene rubber (NBR) was developed. Dopamine was spontaneously oxide polymerized and deposited onto the surface of NBR. Electroless plating of silver was carried out on the poly(dopamine) (PDA)‐functionalized NBR surface. The composition of the NBR surface was studied by X‐ray photoelectron spectroscopy (XPS). XPS results showed that PDA was successfully deposited onto the NBR surface. The morphology of the NBR surface was observed by scanning electron microscopy (SEM). The SEM images showed that PDA had formed a distinctive layer ready for electroless deposition of silver. The catechol/quinone groups on the PDA molecular structure can be used as binding sites for silver ions. The silvered NBR showed high surface conductivity of 1.4 Ω. Copyright © 2011 John Wiley & Sons, Ltd.     

Ion-Free latex films as dual-phase electrolytes: Styrene–butadiene rubber and nitrile–butadiene rubber synthesized by emulsion polymerization with poly-(vinyl pyrrolidone) stabilizer

Ion-free latices of styrene-butadiene rubber (SBR) and nitrile-butadiene rubber (NBR) were synthesized by emulsion polymerization with use of poly (vinyl pyrrolidone) (PVP) stabilizer. The goal was to prepare ion-free latex films, possessing dual-phase latex particle morphology, and swell the films with liquid electrolyte to yield dual-phase polymer electrolytes (DPE). SBR/PVP latex was prepared readily, but NBR/PVP latex was sensitive to coagulation. Differential scanning calorimetric (DSC) and scanning electron microscopic (SEM) analyses of latex films provided morphological evidence concerning particle structure and phase separation. Blends of NBR/PVP and PB/PVP latices (PB = polybutadiene) were also investigated, but particle structure was not present in the blended latex film, even though particle structure was present in the individual NBR/PVP and PB/PVP latex films. After extensive swelling of SBR/PVP latex films, PVP was extracted from the films, and ionic conductivities greater than 10^?3 S/cm were achieved. © 1994-John Wiley & Sons, Inc.     

HDPE／NBR共混物结构和性能的研究

本文对高密度聚乙烯(HDPE)/丁腈橡胶(NBR)共混物的组成、结构、性能和相互作用进行了研究。实验结果表明:少量的NBR能大幅度提高HDPE的冲击韧性和耐环境应力开裂性能。WAXD显示NBR在共混物中呈现一定程度的取向;TEM显示NBR能以平均粒径为0.2 μm的尺寸分散于HDPE中,且形成较牢固的结合;DMA分析发现HDPE与NBR间相互作用而引起α、γ、T_(?)转变温度发生变化。本文对HDPE与NBR相互作用的机理进行了讨论。     

Evaluation of air permeability characteristics on the hybridization of carbon black with graphene nanoplatelets in bromobutyl rubber/epoxidized natural rubber composites for inner‐liner applications

Nanotechnology has been explored recently as a means of enhancing the properties of conventional elastomers for engineering applications. In the current study, the effect of nanofillers on air impermeability properties of Brominated isobutylene‐isoprene rubber (BIIR)/Epoxidized natural rubber (ENR) blend has analyzed for automotive applications. The ENR chosen is ENR 25 and ENR 50 (25 and 50% epoxidation) and prepared the blends in a ratio of 75:25 (BIIR:ENR), and from both blend based composites, a part of carbon black replaced with graphene nanoplatelets (GNP). The physical and thermal properties were compared for both binary blend nanocomposites to study the level of exfoliation and reinforcement behavior of GNP. Morphology studies were employed to reveal the level of interaction between GNP and carbon black in both blends. The influence of epoxidation in the formation of nanostructures in both blends have been evaluated, and the effect of nanostructures on air permeability properties was studied. The air impermeability of BIIR‐ENR 50 nanocomposites were improved with increasing platelet concentration, a 30% improvement in air permeability is obtained for BIIR‐ENR 50 composites over BIIR ‐ENR 25.