Prepared hydrogenated nitrile rubber (HNBR)/organo–montmorillonite nanocomposites by the melt intercalation method

The polymer, Hydrogenated Nitrile‐Butadiene Rubber (HNBR) was melt compounded with organophilic montmorillonite (OMMT). The dispersion of the OMMT in the HNBR matrix was characterized by X‐ray diffraction (XRD), which indicated that at the temperature of 100°C, the organoclay belong to the exfoliated and interlayer structure. The effect of sulfur on the dispersion of OMMT in the polymer matrix was also studied. The vulcanization changed the dispersion of OMMT in polymer matrix greatly and the basal spacing of clay layers is decreased after vulcanization. The mechanical properties, Akron abrasion and the crude oil medium aging‐resistant of HNBR nanocomposites were examined as a function of the OMMT content in the matrix of polymer. The results of the test show remarkable improvement in tensile strength, tear strength, aging‐resistant, and hardness of HNBR nanocomposites than that of unfilled HNBR. It is obvious that the 10 phr of OMMT filled nanocomposites have the best mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Study on wear,cutting and chipping behaviors of hydrogenated nitrile butadiene rubber reinforced by carbon black and in‐situ prepared zinc dimethacrylate

In this study, the wear (Akron and DIN) and the cutting and chipping (C&C) behaviors of hydrogenated nitrile butadiene rubber (HNBR) reinforced by carbon black (N115) and in‐situ prepared zinc dimethacrylate (ZDMA) were investigated. It was validated that ZDMA was more effective than N115 to enhance the wear and C&C resistance of HNBR composites. The Akron wear resistance of the HNBR/N115 composites increased with the content of ZDMA, and the Schallamach ridges observed on the abraded surfaces became less and less clear. With increasing content of ZDMA, the failure mode of the DIN abraded surface underwent the transition from craters to Schallamach ridges, and finally to scratches. The HNBR/N115 composite reinforced by 10 phr ZDMA had the best DIN wear resistance when Schallamach ridges were the dominant failure mode. The use of 30 phr ZDMA can dramatically enhance the C&C resistance of the HNBR/N115 composites. The C&C resistance was suggested to be related to both the variation of the morphology of the C&C ridges and the direction of crack propagation as a function of the content of ZDMA. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and mechanical properties of nitrile butadiene rubber/silicate nanocomposites

Elastomer nanocomposites consisting of nitrile butadiene rubber (NBR) latex and layered silicates are prepared by a modified latex shear blending process aided with ball milling. The mode of dispersion of layered silicates in NBR is partially exfoliated and intercalated when the concentration of layered silicates is below 7.5 wt%, as evidenced by transmission electron microscopy and X-ray diffraction results. The tensile and tear mechanical properties are much higher than that of neat NBR. Specifically, the tensile and tear mechanical properties of the NBR/layered silicates increase by 200 and 60%, respectively. The decomposition temperature of the nanocomposites increases slightly.     

Radiation vulcanization of hydrogenated acrylonitrile butadiene rubber (HNBR)

Raw polymer and compound of hydrogenated acrylonitrile butadiene rubber (HNBR) were subjected to γ-ray irradiation. Crosslinking was found to be the main chemical reaction induced by irradiation; the ratio of chain scission to crosslinking as well as the does at which gelation occurred were determined from gel content measurements to be 0.41 and 3.8 Mrad, respectively. The excellent hot-air and oil-resistant properties should be retained because no formation of double bonds or changing of the nitrile groups were observed with in the optimum dose range. Desired mechanical properties of the vulcanizate may be conveniently obtained by controlling the radiation dose. © 1994 John Wiley & Sons, Inc.     

Influence of molecular parameters and processing conditions on degradation of hydrogenated nitrile butadiene rubbers

The thermomechanical modification of hydrogenated nitrile butadiene rubbers (HNBR) of different molecular parameters was investigated by rheological and light scattering techniques. The influences of acrylonitrile content, degrees of hydrogenation, and Mooney viscosity were examined. A melt blender with Banbury‐type mixing blades was used to condition the rubber samples in the temperature range from 190 to 260°C. Light scattering was used to determine the effect of conditioning on MW and hydrodynamic radius of the rubber molecules. Dynamic viscosity (η′) and storage modulus (G′) were measured for the as‐received and conditioned samples. Experimental results showed that degradation in these rubbers occurred through chain scission and crosslinking. Depending on the molecular parameter, it was found that one of these two mechanisms dominated the degradation process in most brands. Addition of adequate amounts of antioxidants (Irganox 1010 and Irgafos 168) was successful only in preventing degradation by crosslinking. Compared to thermal degradation, thermomechanical degradation was found to be much more severe and progressed at much higher rates. Rheology was found to be a very sensitive technique to structural parameters of the polymers and could be used to detect and identify the mechanism of degradation. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1432–1441, 2005     

氢化丁腈橡胶耐热老化性能的研究

研究了几种不同类型的防老剂对HNBR耐热空气老化的影响。结果表明,采用防老剂RD与MB并用体系硫化胶的综合性能最好;100份生胶中加入1份防老剂RD和1份防老剂MB,在170℃／15MPaxt90的条件下硫化后硫化胶的拉伸强度为28．3MPa,180℃热空气老化24h后其拉伸强度为274MPa,老化48h后其拉伸强度仍然可迭172MPa。     

Continuous process for production of hydrogenated nitrile butadiene rubber using a Kenics® KMX static mixer reactor

A continuous process for hydrogenating nitrile butadiene rubber (NBR) was developed and its performance was experimentally investigated. A Kenics® KMX static mixer (SM) is used in the process as a gas–liquid reactor in which gaseous hydrogen reacts with NBR in an organic solution catalyzed by an organometallic complex such as an osmium complex catalyst. The Kenics® KMX SM was designed with 24 mixing elements with 3.81 cm diameter and arranged such that the angle between two neighboring elements is 90°. The internal structure of each element is open blade with the blades being convexly curved. The dimensions of the SM reactor are: 3.81 cm ID 80 S and 123 cm length and was operated cocurrently with vertical upflow. The NBR solutions of different concentrations (0.418 and 0.837 mol/L with respect to [C?C]) were hydrogenated by using different concentrations of the osmium catalyst solution at various residence times. The reactions were conducted at a constant temperature of 138°C and at a constant pressure of 3.5 MPa. From the experimental results, it is observed that a conversion and/or degree of hydrogenation above 95% was achieved in a single pass from the designed continuous process. This is the first continuous process for HNBR production that gives conversions above 95% till date. Optimum catalyst concentration for a given mean residence time to achieve conversions above 95% were obtained. Finally, a mechanistic model for the SM reactor performance with respect to hydrogenation of NBR was proposed and validated with the obtained experimental results. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Electron beam processing of nylon 6 and hydrogenated nitrile rubber (HNBR) blends: 1. Development of high strength heat‐ and oil‐resistant thermoplastic elastomers

The effects of electron beam irradiation on the morphology, mechanical properties and heat and hot oil resistance of a thermoplastic elastomeric blend of 50/50 nylon 6 and HNBR rubber were investigated. The morphology of the blend was studied by scanning electron microscopy, with special reference to the effects of processing via injection moulding and the radiation dose. Irradiation of extruded pellets at low doses and subsequent injection moulding improved the blend morphology, thereby enhancing the mechanical properties. The tensile strength of the blend increased with radiation dose. The irradiated blends had excellent hot oil resistance and the tensile strength of the blends did not change much after ageing at 150 °C for 72 h. Incorporation of 10 phr SRF black to the blend greatly improved the tension set property. Copyright © 2005 Society of Chemical Industry     

Novel electromagnetic interference shielding effectiveness in the microwave band of magnetic nitrile butadiene rubber/magnetite nanocomposites

A novel nitrile butadiene rubber (NBR)/magnetite (Fe₃O₄) nanocomposite for electromagnetic interference (EMI) shielding at microwave frequency was successfully fabricated. The structural features of as-synthesized magnetite and NBR/Fe₃O₄ were examined by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The number of elastically effective chains, volume fraction of rubber, interparticle distance among conductive sites, polymer–filler interaction, and porosity of the nanocomposites were evaluated. The mechanical properties, including the tensile strength, elongation at break, and hardness, of the composites were measured. The static electrical properties, such as the electrical conductivity, carrier mobility, and number of charge carriers, as a function of magnetite content were evaluated. The interrelation between the electrical conductivity, shielding effectiveness (SE), dielectric constant, and skin depth of the composites are discussed. Finally, the EMI SE versus frequency was tested. The results reveal that an SE of 28–91 dB against EMI in the 1–12 GHz range depended on the loading of the conducting magnetite within the NBR matrix. Accordingly, these nanocomposites may used in the field of microwave absorption devices. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Multiwall‐carbon‐nanotube‐reinforced poly(ethylene terephthalate) nanocomposites by melt compounding

Poly(ethylene terephthalate) (PET) nanocomposites reinforced with multiwall carbon nanotubes (MWCNTs) were prepared through melt compounding in a twin‐screw extruder. The presence of MWCNTs, which acted as good nucleating agents, enhanced the crystallization of PET through heterogeneous nucleation. The incorporation of a small quantity of MWCNTs improved the thermal stability of the PET/MWCNT nanocomposites. The mechanical properties of the PET/MWCNT nanocomposites increased with even a small quantity of MWCNTs. There was a significant dependence of the rheological properties of the PET/MWCNT nanocomposites on the MWCNT content. The MWCNT loading increased the shear‐thinning nature of the polymer‐nanocomposite melt. The storage modulus and loss modulus of the PET/MWCNT nanocomposites increased with increasing frequency, and this increment effect was more pronounced at lower frequencies. At higher MWCNT contents, the dominant nanotube–nanotube interactions led to the formation of interconnected or networklike structures of MWCNTs in the PET/MWCNT nanocomposites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1450–1457, 2007     

The role of rubber characteristics in preparing rubber/clay nanocomposites by melt compounding

Rubber/organic clay (OC) nanocomposites were produced by melt blending. Polar or unsaturated matrices (e.g., NBR and SBR) could easily enter into OC layers, whereas using nonpolar unsaturated rubber (EPDM), without other additives' help, intercalation structure could not be directly obtained. For the EPDM system, an intercalated structure was observed in presence of stearic acid (SA) for composites composed of SA and OC. Transmission electron microscopy observation showed that the dispersion of clay in nonpolar saturated rubber matrix was much poorer than that in polar or unsaturated matrix. The same effect of polar matrix was confirmed by comparison between IIR/OC and BIIR/OC systems. Moreover, using OC pretreated by SA (S‐OC), the dispersion of clay was obviously improved in the investigated nanocomposites, due to the intercalation of SA into OC interlayers. Especially in the nonpolar saturated EPDM system, the intercalation structure could be easily observed. Relative to the corresponding nanocomposites using OC, tensile strengths and the stresses at low strain of NBR and SBR based nanocomposites with S‐OC were significantly improved; while with EPDM nanocomposite, using S‐OC, only tensile strengths were improved but the stresses at low strain were almost the same, which should be related to the different interfacial force between OC and different rubber matrices. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Study on flammability of montmorillonite/styrene‐butadiene rubber (SBR) nanocomposites

The flammability of montmorillonite (MMT)/SBR nanocomposites, prepared by the technique of cocoagulating rubber latex and clay aqueous suspension, was investigated. Flammability studies, performed on the cone calorimeter, showed that the maximum heat release rate (HRR) of SBR decreased from 1987 to 1442 kw/m² with the introduction of nanoclay (20 phr). This nanocomposite had the lowest mass loss rate and the largest amount of char upon combustion compared with conventional SBR composites with the same clay loading and pure SBR. The permeability properties of MMT/SBR composites were also measured. It was deduced that the lowered permeability was responsible for the reduced mass loss rate and hence the lower HRR. Unfortunately, the oxygen index (OI) of the nanocomposites was not as high as expected. Combination of Mg(OH)₂ and clay was effective for the improvement of both mechanical properties and OI. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 844–849, 2005     

Effect of different nanoparticles on thermal,mechanical and dynamic mechanical properties of hydrogenated nitrile butadiene rubber nanocomposites

Organically modified and unmodified montmorillonite clays (Cloisite NA, Cloisite 30B and Cloisite 15A), sepiolite (Pangel B20) and nanosilica (Aerosil 300) were incorporated into hydrogenated nitrile rubber (HNBR) matrix by solution process in order to study the effect of these nanofillers on thermal, mechanical and dynamic mechanical properties of HNBR. It was found that on addition of only 4 phr of nanofiller to neat HNBR, the temperature at which maximum degradation took place (T_max) increased by 4 to 16°C, while the modulus at 100% elongation and the tensile strength were enhanced by almost 40–60% and 100–300% respectively, depending upon nature of the nanofiller. It was further observed that T_max was the highest in the case of nanosilica‐based nanocomposite with 4 phr of filler loading. The increment of storage modulus was highest for sepiolite‐HNBR and Cloisite 30B‐HNBR nanocomposites at 25°C, while the modulus at 100% elongation was found maximum for sepiolite‐HNBR nanocomposite at the same loading. A similar trend was observed in the case of another grade of HNBR having similar ACN content, but different diene level. The results were explained by x‐ray diffraction, transmission electron microscopy, and atomic force microscopy studies. The above results were further explained with the help of thermodynamics. Effect of different filler loadings (2, 4, 6, 8, and 16 phr) on the properties of HNBR nanocomposites was further investigated. Both thermal as well as mechanical properties were found to be highest at 8 phr of filler loading. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Nitrile rubber/organomontmorillonite nanocomposites produced by solution and melt compounding: Effect of the polarity of the quaternary ammonium intercalants

A comparative study of the development of nitrile rubber (NBR) based nanocomposites was performed; two organomontmorillonites (Cloisite 15A and Cloisite 30B) and two procedures for clay dispersion (melt blending and solution intercalation) were used. The nanocomposites were cured with a system based on dicumyl peroxide in the presence of m‐phenylenebismaleimide as a coagent for curing. The dispersion of the organoclay inside the NBR matrix was investigated with transmission electron microscopy and X‐ray diffraction. All the cured systems displayed a combination of intercalated, partially exfoliated clay platelets and confined, deintercalated clay; the degree of dispersion depended on the amount of clay, the type of intercalant, and the intercalation procedure. The highest amount of intercalated/exfoliated clay was obtained with a previous dispersion of the clay (Cloisite 30B) in an NBR solution. All the nanocomposites presented outstanding tensile strength and creep response, and this indicated a reinforcing effect of the layered silicates. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Technological and processing properties of natural rubber layered silicate‐nanocomposites by melt intercalation process

Natural rubber nanocomposites were produced by melt‐mixing of natural rubber with organically modified silicates. For comparison, a pristine‐layered silicate and a nonlayered version [English Indian clay (EIC)] were also included in the study. The layered silicate used was sodium bentonite (BNT) and organoclays used were octadecylamine‐ modified montmorillonite (MMT‐ODA) and methyltallow bis‐2‐hydroxyethyl ammonium‐modified montmorillonite (MMT‐ TMDA). Accelerated sulfur system was used for the vulcanization of the nanocomposites. The dispersion of these silicates was studied by X‐ray diffraction and transmission electron microscopy. The organoclay‐incorporated composites exhibited faster curing and improved mechanical properties. The improvement in the mechanical properties of the composites followed the order MMT‐ODA > MMT‐TMDA > EIC > BNT. The property improvement was attributed to the intercalation/exfoliation of the organically modified silicates because of their high initial interlayer distance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2537–2543, 2006     

Thermomechanical and optical properties of biodegradable poly(L‐lactide)/silica nanocomposites by melt compounding

Poly(L ‐lactide) (PLA)/silica (SiO₂) nanocomposites containing 1, 3, 5, 7, and 10 wt % SiO₂ nanoparticles were prepared by melt compounding in a Haake mixer. The phase morphology, thermomechanical properties, and optical transparency were investigated and compared to those of neat PLA. Scanning electron microscopy results show that the SiO₂ nanoparticles were uniformly distributed in the PLA matrix for filler contents below 5 wt %, whereas some aggregates were detected with further increasing filler concentration. Differential scanning calorimetry analysis revealed that the addition of SiO₂ nanoparticles not only remarkably accelerated the crystallization speed but also largely improved the crystallinity of PLA. An initial increase followed by a decrease with higher filler loadings for the storage modulus and glass‐transition temperature were observed according to dynamic mechanical analysis results. Hydrogen bonding interaction involving C?O of PLA with Si? OH of SiO₂ was evidenced by Fourier transform infrared analysis for the first time. From the mechanical tests, we found that the tensile strength and modulus values of the nanocomposites were greatly enhanced by the incorporation of inorganic SiO₂ nanoparticles, and the elongation at break and impact strength were slightly improved. The optical transparency of the nanocomposites was excellent, and it seemed independent of the SiO₂ concentration; this was mainly attributed to the closed refractive indices between the PLA matrix and nanofillers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of two types of layered silicate on mechanical and barrier properties of hydrogenated acrylonitrile butadiene rubber (HNBR)/layered silicate nanocomposites

Abstract

The role of the type of layered silicate platelets, OMMT and rectorite on the mechanical properties, aging resistance and oxygen permeation properties of HNBR/layered silicate nanocomposites was investigated. The effect of peroxide vulcanising agent on the dispersion of layered silicate in the HNBR matrix was also studied. HNBR was mechanically mixed with layered silicate via melt blending method. The results of the test show remarkable improvement in tensile strength, tear strength, aging resistance and oxygen permeation properties of HNBR nanocomposites than that of unfilled HNBR. It is obvious that the OMMT filled nanocomposites have far better properties than that of rectorite filled HNBR.     

Styrene-acrylonitrile (SAN) layered silicate nanocomposites prepared by melt compounding

Poly(styrene-co-acrylonitrile) (SAN) nanocomposites were successfully made by melt compounding and exhibited improved thermal stability and reduced flammability. The organoclays used in these nanocomposites were based upon fluorinated synthetic mica (FSM) or montmorillonite (MMT). Four different organic treatments were used on the clay surface to study the effect of organic treatment on clay dispersion: dimethyl, bis(hydrogenated tallow) ammonium (DMHTA), methyl tallow bis-2-hydroxyethyl ammonium (MTBHA), triphenyl, n-hexadecyl phosphonium (TPHDP), and 1,2-dimethyl-3-n-hexadecyl imidazolium (DMHDI). Along with studying the effect of clay organic treatment on the nanocomposite formation and flammability, the effect of acrylonitrile content in the SAN on nanocomposite formation and flammability was also studied. The overall findings suggest that dispersion of clay into SAN is rather facile, but certain combinations of organic treatment and clay type resulted in microcomposites rather than nanocomposites. Flammability of these materials was measured by pulse-combustion flow calorimetry (PCFC), also known as micro-cone calorimetry.     

Investigation on the mechanical properties and oil resistance of sulfur cured nitrile rubber/hydrogenated nitrile butadiene rubber blends

Nitrile rubber (NBR)/hydrogenated nitrile butadiene rubber (HNBR) blends with various ratios were compounded with internal mixer and two-roll open mill. Mechanical properties and low-temperature performance (TR10) of the NBR/HNBR blends after aging under different conditions were investigated. Furthermore, equilibrium swelling test and moving die rheometer (MDR) test were used to systematically investigate the effects of HNBR dosage on the crosslink densities and curing behaviors. Vulcanization torque and crosslink densities decreased with an increase in HNBR content. The crosslink density of pure HNBR is higher than that of pure NBR, which is related to the macromolecular structures of the rubber. Compression sets of the NBR/HNBR vulcanizates were correlated with HNBR dosage indicating a linear relationship. Low-temperature performance of the NBR/HNBR blends was improved after being aged in the synthetic hydrocarbon hydraulic oils (SH-1 and SH-2). This work shows that the low-temperature performance and oil resistance could be better balanced by blending NBR with HNBR, while the mechanical properties maintain relatively high level.     

Organic interfacial tailoring of styrene butadiene rubber–clay nanocomposites prepared by latex compounding method

The styrene butadiene rubber (SBR)–clay nanocompounds were prepared by the latex compounding method, and then hexadecyl trimethyl ammonium bromide (C16) and 3‐aminopropyl triethoxy silane (KH550) were added into these nanocompounds on a two‐roll mill to prepare nanocomposites with strong interfacial interaction. The structure and properties of SBR–clay nanocomposites were carefully studied by X‐ray diffraction (XRD) studies, transmission electron microscopy (TEM), Rubber Process Analyzer (RPA), and mechanical testing. Compared with unmodified nanocomposites, the dispersion structure of modified SBR–clay nanocomposites is better with part rubber‐intercalated or part modifier‐intercalated structure. The tensile strength and the modulus at 300% elongation of modified SBR–clay nanocomposites are higher than three times of those of unmodified nanocomposites, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1826–1833, 2007