Effect of bonding agents on styrene butadiene rubber–aluminum powder composites

Effects of various bonding agents—such as the hexamethylene tetramine–resorcinol system (HR), bis[3‐ (triethoxysilyl) propyl] tetra sulfide (Si‐69), and cobalt naphthenate (CoN)—on the mechanical properties of aluminum powder filled styrene butadiene rubber composites were studied, giving emphasis on concentration of bonding agent and loading of aluminum powder. Shore A hardness, modulus, tensile strength, tear strength, heat buildup, etc., were increased by the loading of aluminum powder, and the presence of bonding agents again increased these properties. Rebound resilience and elongation at break were decreased by the addition of aluminum powder. Equilibrium swelling studies showed an improved adhesion between aluminum powder and styrene butadiene rubber (SBR) in presence of bonding agents. Among the various bonding agents used in this study, silane coupling agent (Si‐69) and hexamethylene tetramine–resorcinol (HR) system were found to be better for aluminum powder filled SBR vulcanizates. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 519–529, 2002     

Microwave absorbing rubber composites containing carbon black and aluminum powder

Natural rubber (NR), epoxidized natural rubber (ENR), and chlorosulfonated polyethylene (CSM) composites filled with conductive carbon black and aluminum powder have been prepared by using a two‐roll mill. An electromagnetic interference shielding effectiveness of those rubber composites was carried out in the frequency range of 8–12GHz (X‐band microwave). The increase of filler loading enhanced shielding effectiveness of the rubber composites. Conductive carbon black was more effective in shielding than aluminum powder. Binary filler‐filled rubber composites showed higher shielding effectiveness than that of single filler‐filled rubber composites. It has been observed that the shielding effectiveness of these rubber composites could be ranked in the following order: ENR ≥ CSM > NR, whereas the mechanical properties of the rubber composites were in the order of CSM > ENR > NR. The correlation between shielding effectiveness and electrical conductivity as well as mechanical properties of the rubber composites are also discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Short melamine fiber filled nitrile rubber composites

This article reports the development of a new composite based on acrylonitrile butadiene rubber (NBR) and melamine fiber. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) have been used to study the effect of a dry bonding system in improving the adhesion between the fiber and the matrix. Mechanical properties of the composites are improved in the presence of the dry bonding system comprising of resorcinol, hexamethylene tetramine (hexamine), and hydrated silica. SEM and atomic force microscopic (AFM) images show that there are distinct changes in the fiber‐matrix interphase with the incorporation of the dry bonding system. A strong attachment of the fiber to the matrix is found in the SEM photomicrographs of the tensile fracture surfaces of the composites containing the dry bonding system. AFM section analysis and surface plot show that the improvement in tensile strength and modulus in the presence of the dry bonding system is due to the formation of a well‐defined interphase between the fiber and the matrix. The width of the interphase between the fiber and the matrix is increased in the presence of the dry bonding system, which is reflected in the mechanical properties and aging characteristics. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 544–558, 2003     

高耐磨炉黑填充型粉末丁腈橡胶硫化胶的老化性能

研究了高耐磨炉黑(HAF)填充型粉末丁腈橡胶[P(NBR/HAF)]硫化胶的热空气老化、耐异辛烷/甲苯溶剂及压缩永久变形性能,并与机械混炼的块状丁腈橡胶(BNBR)/HAF硫化胶进行比较。结果表明:P(NBR/HAF)硫化胶的耐热空气老化、耐溶剂及压缩永久变形性能受高分子树脂包覆剂及其用量的影响;P(NBR/HAF)硫化胶的上述性能达到或超过BNBR/HAF硫化胶。     

Composites based on CB/CF/Ag filled EPDM/NBR rubber blends with high conductivity

For many applications of conductive rubbers, it is desirable to endow the conductive rubber with high conductivity at low conductive filler loading. In this work, composites based on ethylene‐propylene‐diene monomer (EPDM) rubber and nitrile‐butadiene rubber (NBR) were prepared using carbon blacks, carbon fibers, and silver powders as fillers. As the weight fraction of silver powder increased, the hardness of composites increased gradually while the tensile strength and elongation at break decreased. SEM revealed that the EPDM/NBR blends exhibited a relatively co‐continuous morphology. The differential scanning calorimetry (DSC) curves reported the EPDM/NBR rubber blends were incompatibility. The thermogravimetry (TG) studies showed that adding a small amount of silver powder could improve the thermal stability of composites. These conductive composites exhibited good electrical property. At room temperature, when the total volume fraction of fillers was 15.20%, the volume resistivity of EPDM/NBR blend was only 0.0058 Ω cm. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41357.     

Preparation,structure and properties of nitrile–butadiene rubber–organoclay nanocomposites by reactive mixing intercalation method

The nanocomposites of nitrile–butadiene rubber (NBR) and organo‐montmorillonite modified by hexadecyltrimethyl ammonium bromide (HMMT) were prepared by the reactive mixing intercalation method in the presence of the resorcinol and hexamethylenetetramine complex (RH). The structure of the NBR–RH–HMMT nanocomposites was characterized by XRD, TEM, FTIR, determination of crosslinking density, and so on. The results showed that the d‐spacing of HMMT increased substantially with RH addition and the layers of HMMT were dispersed in rubber matrix on a nanometer scale. The mechanical properties of the NBR–RH–HMMT nanocomposites were far superior to those of NBR–HMMT composites, and the glass transition temperature of NBR–RH–HMMT nanocomposite was higher than that of NBR. The reactive mixing intercalation method by introducing RH could enhance the interface combination between the rubber and the organoclay through the interactions of RH with NBR and modified clay. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1905–1913, 2006     

Particle size distribution,mixing behavior,and mechanical properties of carbon black (high‐abrasion furnace)–filled powdered styrene butadiene rubber

High‐abrasion furnace black (HAF, grade N330)–filled powdered styrene butadiene rubber [P(SBR/HAF)] was prepared and the particle size distribution, mixing behavior in a laboratory mixer, and mechanical properties of P(SBR/HAF) were studied. A carbon black–rubber latex coagulation method was developed for preparing carbon black–filled free‐flowing, noncontact staining SBR powders, with particle diameter less than 0.9 mm, under the following conditions: carbon black content > 40 phr, emulsifier/carbon black ratio > 0.02, and coating resin content > 2.5 phr. Over the experimental range, the mixing torque τ_α of P(SBR/HAF) was not as sensitive to carbon black content and mixing temperature as that of HAF‐filled bale SBR (SBR/HAF), whereas the temperature build‐up ΔT showed little dependency on carbon black content. Compared with SBR/HAF, P(SBR/HAF) showed a 20–30% mixing energy reduction with high carbon black content (>30 phr), which confers to powdered SBR good prospects for internal mixing. Carbon black and the rubber matrix formed a macroscopic homogenization in P(SBR/HAF), and the incorporation step is not obvious in the internal mixing processing results in these special mixing behaviors of P(SBR/HAF). A novel mixing model of carbon black–filled powdered rubber, during the mixing process in an internal mixer, was proposed based on the special mixing behaviors. P(SBR/HAF) vulcanizate showed better mechanical properties than those of SBR/HAF, dependent primarily on the absence of free carbon black and a fine dispersion of filler on the rubber matrix attributed to the proper preparation conditions of noncontact staining carbon black–filled powdered SBR. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2494–2508, 2004     

Wood flour: A new filler for the rubber processing industry. III. Cure characteristics and mechanical properties of nitrile butadiene rubber compounds filled by wood flour in the presence of phenol‐formaldehyde resin

Nonmodified and corona‐activated conifer wood flour was evaluated as filler to nitrile butadiene rubber (NBR) compounds containing different amounts of phenol‐formaldehyde resin (PFAR) by studying the cure characteristics and the mechanical properties of the filled compounds. It was found that the PFAR affects considerably the cure characteristics and the mechanical properties of the wood flour–filled NBR compounds due to a presumable action as an interface interactions modifier. Acting as an antiaging agent it improves also their thermal‐oxidative stability. The optimal amount of PFAR regarding the cure characteristics and mechanical parameters is of 15 phr/100 phr wood flour. The addition of PFAR just before the wood flour is preferable because of both its better homogenization in the rubber matrix and its lower adsorption by the wood flour, leading to an improvement of the mechanical properties of the wood flour–filled NBR compounds. The replacement of nonmodified wood flour by corona‐activated wood flour leads to additional increase of the mechanical parameters without significant affect of the optimum cure time, aging resistance, and water adsorption. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 95–101, 2004     

Mechanical and viscoelastic properties of short fiber reinforced natural rubber composites: effects of interfacial adhesion,fiber loading,and orientation

The effect of a two-component dry bonding system consisting of resorcinol and hexamethylene tetramine on the mechanical and viscoelastic properties of short sisal fiber reinforced natural rubber composites has been studied. The studies were conducted with chemically treated and untreated short sisal fibers. Treated fibers impart better mechanical properties to the composites. By mixing with short fibers, the dynamic storage modulus (E') of natural rubber composites was improved. The effects of fiber-matrix adhesion on the mechanical and viscoelastic properties of the composites were investigated. The storage moduli and mechanical loss increased continuously with an increase in fiber loading but decreased with an increase of temperature. The influence of the fiber orientation on the mechanical and viscoelastic properties is discussed.     

Preparation and properties of nitrile rubber/superfine down powder composites

The purpose of this study was to improve utilization rate of waste protein materials. In this article, down fiber was ground into superfine down powder (SDP) and then filled into nitrile rubber (NBR) directly. The cure‐curve, dynamic rheological behavior, morphology, tensile property, and thermal properties of NBR/SDP composites were studied. The results showed that SDP formed a developed but weak filler–filler network, which resulted in obvious “Payne effect,” the increased storage modulus, loss tangent and complex viscosity of the NBR/SDP composites. SDP could be distributed uniformity in the NBR matrix, but the large sizes of most SDP weaken the interaction between the particles and NBR matrix. The tensile property was improved by high SDP load. The SDP decreased the temperature at 5% weight loss of the NBR/SDP composites, but not apparently affected the maximum weight loss rate of the NBR. At last, the results of this study suggested that SDP was potential to be one of the available additives fillers in rubber industry, as long as the smaller size of SDP was achieved. POLYM. COMPOS., 34:1136–1143, 2013. © 2013 Society of Plastics Engineers     

Bonding properties between nitrile–butadiene rubber and aluminum alloy treated by anodizing methods

In this work, the bonding properties between the LD7 aluminum alloy anodized by sulfuric acid or phosphoric acid and nitrile–butadiene rubber (NBR) were investigated. The bonding properties between the anodized aluminum alloys and NBR were compared with those between aluminum alloys treated by burnishing or sandblasting and NBR. The results revealed that, in comparison with sulfuric acid anodized samples, samples anodized in phosphoric acid solutions showed higher 90° peel strength. Under the same conditions, an increase in the anodic film thickness in the studied range may improve the adhesion property between rubber and an aluminum alloy. In comparison with aluminum alloys treated by burnishing or sandblasting, the surface of the anodized aluminum alloy showed homogeneously dispersed pores, which resulted in better and homogeneous bonding properties. A vacuum‐drying process on the anodized aluminum alloys after they were coated with adhesives facilitated penetration of the adhesive molecules into the pores on the oxide layer, which considerably improved the bonding properties. In addition, rubber macromolecules could also penetrate the pores in the aluminum oxide layer, leading to a strong physical anchor–hold interaction after a long time of soaking and diffusion. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Coordination cross‐linking gadolinium salt/acrylonitrile‐butadiene rubber composite: Its preparation,characterization, and functional properties

A novel rubber composite of acrylonitrile‐butadiene rubber (NBR) filled with gadolinium salt (GS) particles was prepared for the first time and vulcanized via coordination reactions. The resulting materials exhibit good mechanical properties. Structural analyses indicate that the composite is a kind of elastomers based on coordination cross‐linking interactions between the nitrile groups (–CN) of NBR and gadolinium ions. The mechanical properties of vulcanized GS/NBR rubber are altered when the cross‐link density is changed in the composites. These materials show good irradiation resistance because of the introduction of GS. POLYM. COMPOS., 34:1013–1019, 2013. © 2013 Society of Plastics Engineers     

Thermal properties of graphite‐loaded nitrile rubber/poly(vinyl chloride) blends

The thermal properties (thermal conductivity, thermal diffusivity, and specific heat capacity) of nitrile rubber (NBR)/poly(vinyl chloride) (PVC) blends were measured in the temperature range of 300–425 K. The incorporation of graphite into the NBR/PVC (30/70) matrix improved its thermal properties. Moreover, these properties slightly changed with the temperature. The thermal conductivity values of the prepared samples were compared with values modeled according to the Maxwell–Eucken, Cheng–Vachon, Lewis–Nielsen, geometric mean, and Agari–Uno models. The Agari–Uno model best predicted the effective thermal conductivity for the whole range of blend ratios and for the whole range of graphite contents in NBR/PVC (30/70)/graphite composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Design and preparation of cross‐linked α‐methylstyrene‐acrylonitrile copolymer nano‐particles for elastomer reinforcement

Crosslinked α‐methylstyrene and acrylonitrile (MStAN) copolymer particles in a latex form were synthesized by free radical emulsion polymerization. The particles took a spherical shape with an average size of 53.1 nm in a narrow distribution. When filled into styrene‐butadiene rubber (SBR), nitrile‐butadiene rubber (NBR), and natural rubber (NR), the MStAN nano‐particles exhibited excellent reinforcing capabilities and the best in NBR. By the employment of heat treatment, mechanical properties of the MStAN‐filled SBR composites had got remarkable further improvements. But mechanical properties, together with the morphology, of the MStAN‐filled NBR composites, varied little after heat treatment, which, however, divulged the naturally good compatibility between the MStAN particles and the NBR matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Properties of alumina nanoparticle‐filled nitrile‐butadiene‐rubber/phenolic‐resin blend prepared by melt mixing

Effect of alumina nanoparticle (ANP) on the properties of rubber compounds based on nitrile‐butadiene‐rubber (NBR) and NBR/phenolic‐resin (PH) blend is examined. To investigate the surface characteristics of the nanoparticles on the performance of nanoalumina‐filled compounds, trimethoxyvinylsilane (MVS) is attached chemically on the surface of ANP through an appropriate functionalization process. Various NBR and NBR/PH compounds filled with ANP and functionalized ANP (f‐ANP) are prepared via melt mixing using traditional open two‐roll mill. Microscopic analysis carried out by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) reveals good dispersion of nanoalumina within the rubber matrix, indicating the effectiveness of the melt mixing for fabrication of the rubber/alumina nanocomposites. Nanocomposites of NBR and NBR/PH are subjected to various physical and mechanical tests including swelling, tensile, abrasion, and thermal tests and the role of ANP and f‐ANP on these properties are discussed. The results obtained based on this analysis suggest that as‐received ANP can provide good interaction with NBR possibly due to hydrogen bonding between hydroxyl group present on the nanoparticle surface and acrylonitrile group of NBR. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers     

Curing characteristics and mechanical properties of alkali‐treated grass‐fiber‐filled natural rubber composites and effects of bonding agent

To improve adhesion between fiber and matrix, natural rubber was reinforced with a special type of alkali‐treated grass fiber (Cyperus Tegetum Rox b). The cure characteristics and mechanical properties of grass‐fiber‐filled natural rubber composites with different mesh sizes were studied with various fiber loadings. Increasing the amount of fibers resulted in the composites having reduced tensile strength but increased modulus. The better mechanical properties of the 400‐mesh grass‐fiber‐filled natural rubber composite showed that the rubber/fiber interface was improved by the addition of resorcinol formaldehyde latex (RFL) as bonding agent for this particular formulation. The optimum cure time decreased with increases in fiber loading, but there was no appreciable change in scorch time. Although the optimum cure time of vulcanizates having RFL‐treated fibers was higher than that of the other vulcanizates, it decreased with fiber loading in the presence of RFL as the bonding agent. But this value was lower than that of the rubber composite without RFL. Investigation of equilibrium swelling in a hydrocarbon solvent was also carried out. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3151–3160, 2006     

Reactive bonding of natural rubber to metal by a nitrile–phenolic adhesive

The mechanism of adhesive bonding of rubber to metal using an interlayer of bonding agent (adhesive) is discussed with respect to various physical and chemical events such as adsorption at the metal surface, chemical crosslinking within the adhesive, interdiffusion, and formation of interpenetrating networks at the rubber–adhesive interface. An investigation on the peel strength of a natural rubber (NR)–adhesive–metal joint, made by vulcanization bonding using nitrile–phenolic adhesive containing various concentrations of toluene diisocyanate–nitrosophenol (TDI–NOP) adduct, is presented. A single‐coat adhesive, consisting of a p‐cresol phenol formaldehyde resin, nitrile rubber (NBR), and vulcanizing agents in methyl ethyl ketone solvent, was selected for the study. Considerable improvement in the peel strength was obtained by the incorporation of TDI–NOP adduct into the nitrile–phenolic adhesive. The peel strength increases as the concentration of TDI–NOP adduct in the adhesive composition increases, then levels off with a transition from interfacial failure to cohesive tearing of rubber. The peel strength improvement is believed to be attributed to the interfacial reactions between the bonding agent and natural rubber, when TDI–NOP adduct is incorporated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2597–2608, 2001     

Short sisal fiber reinforced styrene-butadiene rubber composites

Styrene-butadiene rubber (SBR) composites were prepared by incorporating short sisal fibers of different lengths and concentrations into the SBR matrix in a mixing mill according to a base formulation. The curing characteristics of the mixes were studied and the samples were vulcanized at 150°C. The properties of the vulcanizates such as stress-strain behavior, tensile strength, modulus, shore-A hardness, and resilience were studied. Both the cured and uncured properties showed a remarkable anisotropy. It has been found that aspect ratio in the range of 20–60 is effective for sufficient reinforcement. The mechanical properties were found to increase along and across the grain direction with the addition of fibers. The effects of fiber length, orientation, loading, type of bonding agent, and fiber-matrix interaction on the properties of the composites were evaluated. The extent of fiber orientation was estimated from green strength measurements. The adhesion between the fiber and the rubber was enhanced by the addition of a dry bonding system consisting of resorcinol and hexamethylene tetramine. The bonding agent provided shorter curing time and enhanced mechanical properties. The tensile fracture surfaces of the samples have been examined by scanning electron microscopy (SEM) to analyze the fiber surface morphology, orientation, fiber pull-out, and fiber-matrix interfacial adhesion. Finally, anisotropic swelling studies were carried out to analyze the fiber-matrix interaction and fiber orientation. © 1995 John Wiley & Sons, Inc.     

The order addition effect of carbon black/graphite on the electrical properties of rubber composites

Acrylonitrile‐butadiene rubber (NBR) filled with two types of fillers [high abrasion furnace carbon black (C), and graphite (G)] is made to find out the effect of order addition of C and G on the electrical conductivity of the composites. The temperature and frequency dependence of the (dc and ac) conductivity and dielectric constants have been measured. The values of the thermal expansion and thermal conduction coefficient of NBR rubber lead to the difference in I–V characteristics between CB‐ and G‐NBR rubber composites during the measurement. When graphite is first added to NBR, the electrical conductivity of (GC_20‐20) matrix is larger than that of the (CG_20‐20) matrix, whereas the carbon black is added first. At low temperature (T < 90°C), the higher values of the dielectric constant (ε′) for the sample GC_20‐20 compared with that of the CG_20‐20 sample is due to the conducting nature and structure of graphite, whereas the carbon shows less crystallinity and conductivity than graphite. Opposite behavior is noticed at temperature higher than 90°C. The dc conductivity of all composites increases with increasing temperature exhibiting a positive temperature coefficient of conductivity (PTCσ). The conductivity at high temperatures region is controlled by the thermal excitation transport mechanism, whereas at low temperatures region is dominated by tunneling process. The increase in the value of dielectric constant (ε′) with temperatures for the sample GC_20‐20 compared with the sample CG_20‐20 is due to the conducting nature and structure of graphite, and the carbon less crystalline than the graphite. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Properties of silica‐filled styrene‐butadiene rubber compounds containing acrylonitrile‐butadiene rubber: The influence of the acrylonitrile‐butadiene rubber type

Because silica has strong filler‐filler interactions and adsorbs polar materials, a silica‐filled rubber compound exhibits poor dispersion of the filler and poor cure characteristics in comparison with those of a carbon black‐filled rubber compound. Acrylonitrile‐butadiene rubber (NBR) improves filler dispersion in silica‐filled styrene‐butadiene rubber (SBR) compounds. The influence of the NBR type on the properties of silica‐filled SBR compounds containing NBR was studied with NBRs of various acrylonitrile contents. The composition of the bound rubber was different from that of the compounded rubber. The NBR content of the bound rubber was higher than that of the compounded rubber; this became clearer for NBR with a higher acrylonitrile content. The Mooney scorch time and cure rate became faster as the acrylonitrile content in NBR increased. The modulus increased with an increase in the acrylonitrile content of NBR because the crosslink density increased. The experimental results could be explained by interactions of the nitrile group of NBR with silica. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 385–393, 2002