Nitrile Butadiene Rubber Nanocomposites Research Articles

Sustainable Rubber Nanocomposites for Hydrogen Sealings: Impact of Carbon Nano-Onions and Bio-Based Plasticizer

Additives play a crucial role in modifying and enhancing the properties of rubbers, improving mechanical strength, thermal stability, and chemical resistance to make them more suitable for various applications. The rubber industry faces challenges related to high resource consumption and toxic emissions, which are further impacted by the use of performance-enhancing additives. In hydrogen storage systems, tailored additives are required for rubbers to withstand elevated temperatures and high pressures, preventing hydrogen-induced swelling, a major cause of sealing failure. Herein, a novel form of carbonaceous material, carbon nano-onions (CNOs), and the bio-based plasticizer additive epoxidized soybean oil (ESO) are utilized in conventional silica-filled nitrile butadiene rubber (NBR) nanocomposites to develop low-carbon manufacturing high pressure hydrogen resistant O-rings for sealing applications. The results reveal that the incorporation of CNOs increases the crosslinking density (vc), assisted by ESO, in silica-filled NBR nanocomposites. While the conventional adipate-based plasticizer and ESO were found to be susceptible to high pressure hydrogen exposures, ESO demonstrated sustained compressive sealing properties with increase in von-Mises stress and in elevated thermo-oxidative conditions over time. The results of the life cycle assessment (LCA) recommend ESO for low-carbon manufacturing in rubber processing over conventional plasticizers.

Nanokaolin reinforced carboxylated nitrile butadiene rubber/polyurethane blend-based latex with enhanced tensile properties and chemical resistance

The demand for gloves (e.g., disposable gloves, medical gloves) is increasing due to the Coronavirus disease 2019 (COVID-19) pandemic. Stability in the supply chain in the glove industry is important, and thus strategies are used to solve the problem of the shortage of nitrile gloves. The blending of nitrile butadiene rubber (NBR) with polyurethane (PU) and the use of the nanocomposite concept is among the feasible approaches. The present study aims to investigate the effects of nanokaolin (NK) on the tensile and chemical properties of carboxylated nitrile butadiene rubber (NBR)/polyurethane (PU) latex blends. Three different loadings of NK (10, 20, and 30 parts per hundred rubber) were added to the NBR/PU (at a blending ratio of 85/15). The zeta potential showed that all the NBR compounds exhibit good colloidal stability. The incorporation of NK increased the crosslink density and tensile strength of the NBR/PU latex blends. The highest tensile strength was achieved when the NK loading was 20 phr. All the NBR blends and nanocomposites (NBR/PU-based) possess tensile properties that fulfill the requirements for glove application. The chemical resistance of NBR compounds was increased by the incorporation of NK due to the higher crosslink density and barrier properties contributed by the NK.

Scaling laws of Mullins effect in nitrile butadiene rubber nanocomposites

Rubber nanocomposites experiencing cyclic deformation undoubtedly exhibit Mullins effect whose underlining mechanisms are not yet clear. Herein this effect in nitrile butadiene rubber nanocomposites is systematically investigated for revealing the influences of pre-strain interval, loading and unloading velocities, temperature, filler type and content, as well as crosslinking agent. The results show that the recovery hysteresis energy and accumulative softening energy of the nanocomposites can be superposed onto master curves as a function of microscopic strain of the rubber phase, revealing that both involving the viscoelastic deformation of the rubber phase. Especially the recovery hysteresis highly depending on temperature and loading and unloading velocities is connected to the viscoelasticity of nonideally crosslinked rubber network in the nanocomposites. On the other hand, the accumulative softening energy loss comes from recovery retardation of rubber chains and is somewhat sensitive to the filler, temperature and crosslinking agent. The investigation would be instructive to clarify the physical origin of Mullins effect to produce low dissipation rubber nanocomposites.

Enhancement of Dielectric Performance of Polymer Composites via Constructing BaTiO3–Poly(dopamine)–Ag Nanoparticles through Mussel-Inspired Surface Functionalization

We demonstrate the synthesis of a novel core–satellite-structured BaTiO3–poly(dopamine)–silver (BT–PDA–Ag) nanoparticle for improving dielectric properties of nitrile-butadiene rubber (NBR) nanocomposites. The BT–PDA–Ag nanoparticles are synthesized by dopamine oxidative polymerization and electroless plating of silver. The Ag nanoparticles decorated on the BT nanoparticles enhanced the dielectric constant of NBR nanocomposites due to the increased conductivity of the filler/matrix interlayer and nanocapacitor structure. In addition, the incorporation of the BT nanoparticles prevented the continuous connection of Ag nanoparticles and suppressed the formation of a conductive path in the NBR matrix. Moreover, the ultrasmall Ag nanoparticles trapped the carriers by Coulomb blockade and quantum confinement effects, which results in low dielectric loss and electrical conductivity of nanocomposites. The proposed method with simplicity and scalability can be adapted to process high-dielectric polymer nanocomposites.

Mechanical properties development of high-ACN nitrile-butadiene rubber/organoclay nanocomposites

The nanocomposites of nitrile-butadiene rubber (NBR) with high acrylonitrile content and Cloisite 30B were prepared in the presence of the resorcinol and hexamethylenetetramine (RH) complex as a compatibiliser. The structure of the NBR nanocomposites was characterised by cure characteristics, XRD, TEM and mechanical properties. The mechanical properties of the nanocomposites containing RH were far superior to those of NBR nanocomposites alone. Some hyperelastic models were approved on comparative study of tensile properties and the effect of RH compatibiliser on the material parameters of the models was investigated. The Mori–Tanaka and Halpin–Tsai models were used to estimate the modulus of prepared nanocomposites and compared with experimental results. The effect of RH on the intercalation/exfoliation of silicate layers was investigated from combination of effective particle method and Mori–Tanaka theory. This technique showed that the average number of silicate layers in each effective particle can decrease with RH compatibiliser.

Efficient Nanocomposite formation of Acyrlo Nitrile Rubber by incorporation of Graphite and Graphene layers: Reduction in Friction and Wear Rate

Graphite (G) and its nano form Graphene (nG) are one of the most admirable fillers for incorporating multifunctional attributes in polymer/elastomer matrix. Use of such fillers in polymers/elastomers has enhanced their several properties and applicabilities. Acrylo Nitrile Butadiene Rubber (NBR) is a workhorse of the several industrial applications especially for automotive rubber products and in hydraulic area. Enhanced tribological properties of NBR are one of the crucial requirements for sealing applications. In this field we are first to report the anti wear study on NBR filled with Graphite and graphene layers. Sliding wear test showed that the wear parameters of NBR nanocomposites have significantly improved. The incorporation of graphene in NBR has reduced coefficient of friction 2.3 times more than that of graphite incorporated NBR. The reason for the same is proposed that the homogeneous distribution of nano layers in the elastomer matrix, the enhanced self lubrication of graphene, the favourable interface stability of composite contributed together to the improved wear properties of NBR nanocomposites. Along with it we have also investigated the effect of applied load, revolution per minute i.e., sliding speed on wear properties. The incorporation of fillers (G &nG) in NBR has also improved the hardness and tensile properties other than tribological properties. Electrical conductivity of graphene filled NBR has also been reported in comparison to graphite filled NBR and pristine NBR. The prepared graphene and the nanocomposites have also been fully characterized by different sophisticated techniques viz HR-TEM, FEG-SEM, Micro Raman, FT-IR. Improvement in such properties of NBR will definitely widen its role in multiple applications.

Multifunctional and specific interactions of CNTs in NBR and HNBR

There are different techniques in practice to disperse multiwalled carbon nanotubes (MWCNTs) in elastomers. In the present work, commercially available MWCNTs NANOCYL NC 7000™ are used as filler. A synthetic Nitrile Butadiene Rubber (NBR) and Hydrogenated Nitrile Butadiene Rubber (HNBR) were used as polymer matrix for the composites prepared by melt blending. The filler dispersion in HNBR was studied through Transmission Electron Microscopy (TEM). The mechanical properties are investigated through strain sweep and tensile tests. Dielectric measurements are carried out to study electrical conductivity of the nanocomposites. Dynamic mechanical measurements showed an enhanced Payne effect and improvement in stiffness with increase in CNTs content into rubber matrix An improvement in electrical and mechanical properties in both NBR and HNBR system resulted by an increase in filler loading. The mechanical and electric percolation threshold of CNTs was found at very low filler volume fraction. Equilibrium swelling experiments were used to study polymer-filler interaction with the help of Kraus plot and diffusion coefficient. NBR showed higher polymer-filler interaction compared to HNBR. In NBR nanocomposites, CNTs showed higher interaction than carbon black. Good dispersion and effective interaction of the CNTs with the polymer led to significant mechanical reinforcing effects.

Preparation and characterization of nitrile butadiene rubber-nanoclay composites with maleic acid anhydride as compatibilizer. Part II

The influence of maleic acid anhydride-treated organoclay (MOC) content (i.e. 1, 3, 5, 10, 20 phr) relative to the micrometer clay (i.e. 10, 20 phr) on the nitrile butadiene rubber (NBR) compounds was analyzed through physico-mechanical properties (i.e. tensile strength, elongation at break, Young’s modulus, hardness Shore A and crosslink density). The effect of (MOC) content on aging resistance of NBR nanocomposites at 90 ± 1°C for different time intervals (namely 2, 4, 6, 7 days) was also investigated through changes in aging properties, compared to unmodified micrometer clay composites (10, 20 phr) and unfilled NBR. The constants of the relative change in the physico-mechanical properties of NBR vulcanizate compounds were calculated. Physico-mechanical properties demonstrated an increase in the crosslink density for the MOC (3 phr)-incorporated NBR compound compared to conventional composites and pure NBR. Thermal aging data of the aged samples revealed that under aerobic hot aging conditions, NBR compounds undergo crosslink reactions that lead to embrittlement and ultimately failure. Incorporation of MOC filler, however, resulted in significant improvement of the degradation profile of the nanocomposites at 90 ± 1°C. Loss of tensile strength and flexibility during aging of the NBR nanocomposites with 3 phr MOC was milder, relative to unfilled polymer, indicating a restricted degradation by the MOC-filled rubber, thus prolonging the modulus. However, beyond 3 phr MOC, a deterioration in the aging properties of the nanocomposites takes place.

Exfoliated sodium-montmorillonite in nitrile butadiene rubber nanocomposites with good properties

We prepared and utilized a novel ultrafine fully-vulcanized powder nitrile butadiene rubber (UFPNBR)/sodium montmorillonite (Na-MMT) nanocompound powder, in which nanoscale UFPNBR particles and nanoscale platelets of Na-MMT were isolated and stuck each other. When the UFPNBR/Na-MMT nanocompoud powder was mixed with crude nitrile butadiene rubber (NBR), UFPNBR particles could be easily dispersed in NBR matrix because of good compatibility, and nanoscale Na-MMT was also dispersed well in NBR matrix due to the carrier aidance of UFPNBR particle, thus the NBR/UFPNBR/Na-MMT ternary nanocomposites adapting to industry was fabricated. X-ray diffraction test and scanning electron microscopy (SEM) observation indicated that nanoscale Na-MMT was dispersed well in NBR matrix. Compared with NBR/Na-MMT binary composites, NBR/UFPNBR/Na-MMT ternary nanocomposites have shorter vulcanization time and higher flame retardancy due to the exfoliated Na-MMT in NBR matrix.

Comparison Studies on Nitrile-Butadiene Rubber Nanocomposites Depending on the Organically Modified Montmorillonites

A various organic modifiers depending on the substituents of ammonium ions were synthesized and used to prepare organically modified montmorillonite (OMMT). Nitrile-butadiene rubber (NBR)/OMMT nanocomposites could be obtained using melt-compounding followed by hot-press vulcanization. d-Spacings of OMMT were changed as the chemical structures of modifiers were varied. X-ray diffraction (XRD) and tensile measurements of NBR nanocomposites revealed that the structures of organic modifiers affect the properties of NBR nanocomposites after vulcanization. Long alkyl chain of OMMT induced higher interaction between NBR and OMMT, resulting in higher tensile strength, Young’s modulus, and hardness of NBR/OMMT nanocomposites.

Characteristics of nitrile–butadiene rubber layered silicate nanocomposites with silane coupling agent

AbstractNanocomposites of organophilic montmorillonite (C18‐MMT), nitrile–butadiene rubber (NBR), and a coupling agent were produced during a melt compounding process at room temperature. During the process, it was clearly observed that organo‐MMT particles were exfoliated into nanoscale layers of approximately 1–30 nm thickness, in addition to their original 40 μm thickness. These MMT layers were uniformly dispersed in the NBR matrix. The effects of a coupling agent such as 3‐(mercaptopropyl)trimethoxy silane in C18‐MMT/NBR nanocomposites were studied. The C18‐MMT/NBR nanocomposites in the presence of the coupling agent were identified and characterized by X‐ray diffraction, transmission electron microscopy, a universal testing machine, thermogravimetric analysis, and IR spectroscopy. It was observed that an additional silane coupling agent, 3‐(mercaptopropyl)trimethoxy silane, enhanced the chemical interaction and was accompanied by the formation of SiOSi coupling bonds between C18‐MMT and the coupling agent and SiC coupling bonds between NBR and the coupling agent. This work resulted in improved properties of organo‐MMT/NBR nanocomposites because of the nanoscale effects and strong interaction of the coupling bonds between NBR and organo‐MMT. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2633–2640, 2003