NBR Rubber Research Articles

Electrical and mechanical behaviors of rubber composites based on polar elastomers with incorporated Cu-based alloy

Dielectric elastomers with conducting inorganic fillers offer a wide range of uses, including capacitive energy storage, elastomer sensors, actuators, and many more. In this approach, low dielectric loss and high dielectric constant may be made possible by ternary composites that use metal alloy components as reinforcing fillers. Here, Cu-based alloy was added to acrylonitrile-butadiene rubber (NBR) to produce ternary rubber composites. Unfortunately, the Cu–Al–Zn alloy’s material incompatibility with the rubber matrix typically leads to phase separation, void formation, and particle aggregation, all of which have a dramatic negative impact on performance. Using 3-(trimethoxysilyl)propyl methacrylate as a coupling agent, Cu–Al–Zn alloy particles were uniformly dispersed onto the NBR rubber matrix through surface modification. By using scanning electron microscopy, the appropriate reinforcement of modified Cu-based alloy particles into NBR was carefully examined. The effect of modified Cu–Al–Zn alloy loading on the swelling behavior of the composite was also investigated. The findings show that the shape and dispersion state of modified Cu–Al–Zn alloy were important for the dielectric characteristics of the NBR compounds. By adding reinforced modified Cu-based alloy to the NBR matrix, mechanical characteristics were significantly improved. The uniform dispersion of modified Cu–Al–Zn alloy particles and strong interfacial compatibility with rubber matrix are the reasons for the outstanding performance of NBR composites, which suggests high-performance dielectric composite.

New elastomeric ceramizable composites based on butadiene-acrylonitrile rubber filled with talc

One of the most serious drawbacks of polymeric materials is their flammability. This poses problems for their use as building materials. The production of elastomeric composites capable of ceramization is one way of making such materials flame-retardant and thus improving their fire safety. Here, we propose the production of ceramizable, highly filled composites based on NBR rubber containing talc and fluxing agent in the composition. The research showed low flammability (88 % reduction in FIGRA), good rheological properties, high mechanical strength of the vulcanizates (tensile strength at break exceeding 7 MPa) and the ability to produce a strong ceramic phase (up to 77 % increase in required destructive force on ceramizable samples). This confirmed the high flame resistance of the composites tested. In the future, similar composites could be considered for the design of cables that supply fire protection systems, escape route lighting or elevators.

Quantification of natural rubber blends by reflection/reflectance infrared and confocal Raman spectroscopy: a comparison of statistical methods.

The blend of butadiene and acrylonitrile copolymer (NBR) with natural poly-cis-isoprene (NR) shows increased resistance to swelling in solvents in comparison to the individual components. In aerospace, NBR rubber is used as thermal protection for rockets and shall not contain other polymers, even in low contents, otherwise, it can affect the protection performance and rocket safety by causing detachment of the elastomer/propellant interface; therefore, this investigation presents methodologies to determine the NR/NBR contents. This study explores different analytical techniques, such as Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy, in the mid-infrared (MIR) by reflection and in the near-infrared by reflectance (NIRA) modes, Furthermore, quantification strategies by univariate, bivariate and multivariate (chemometric) models are evaluated and compared. A proposed methodology, based on multivariate Raman microscopy with partial least squares regression (PLS), showed high linearity (R2 > 0.99) and low error (< 0.82 %). The validation of FT-MIR data for the CH3, which presented lower error (1.3%) than vinylidene band (6%), showed that both methodologies (reflection and NIRA reflectance) can be used for the quantification of NR in NR/NBR. These results constitute a contribution to the state of the art in researching industrial and aerospace elastomeric applications.

Influence of Atmospheric Conditions on the Polymer Composite Based on NBR Rubber and Functionalized Protein Waste

Technology has progressed a lot in the last 20 years, today it is possible to obtain new polymer composites that show performance properties. The ever-increasing demand for new high-performance materials has determined the appearance of new polymer structures based on elastomers and various wastes (protein, cellulosic, elastomeric, etc.) from various fields (shoes, leather goods, etc.). This paper describes the obtaining and characterization of polymer composites based on NBR rubber (butadiene-co-acrylonitrile) and protein waste from the footwear and leather goods industry, cryogenically ground to micrometric dimensions and modified with PDMS (polydimethyl siloxane). PDMS has the role of a plasticizer, but at the same time it improves the dispersion of protein waste mixed in the polymer matrix. The polymer composites were obtained by the mixing technique and tested from a physical-mechanical point of view according to the standards in force. The characterization in normal condition and accelerated aging at 70°C for 168 h (it was carried out hot, using the hot air circulation oven method) was carried out after the samples were subjected to conditioning for 24 h at ambient temperature. Also, the polymer composite samples were subjected for 365 days to atmospheric conditions (sun, rain, wind, hail, light, etc.) to see their influence on the properties of the obtained polymer composites.

Achieving enhanced electromagnetic shielding by novel flexible rubber based nanocomposite with the incorporation of nickel spinal ferrites and polyaniline

The chemical oxidative method was used for the polymerization of the polyaniline (PANI) using APS as an oxidant and formic acid as a dopant and co-precipitation method was used for the precipitation of nickel ferrites (NiFe). Polyaniline used to impart conductivity and nickel ferrites for magnetic permeability to achieve high EMI shielding. Seven different composites were made varying their composition and tested for various properties like morphology, DC conductivity, EMI shielding etc. In SEM analysis it was discovered that PANI and NiFe particles dispersed in NBR rubbers uniformly. DC conductivity was also rised to 286 S/cm from 10−7 S/cm. XRD and particle size analysis used to conform the successful fabrication of PANI and NiFe and their particle size respectively. DSC confirmed that the melting point dosned by the addition of PANI and NiFe in NBR rubber. EMI shielding of almost 52 dB was achieved while pure rubber provide only 1–2 dB.

OCSiAl is reinforcing thermoplastics and rubber with graphene nanotubes

On February 28, 2023, OCSiAl announced it had expanded its portfolio of products for reinforcing and adding conductivity to rubbers with new graphene nanotube technologies for NBR rubber.

Tuning the properties of NBR/BaFe11.5Co0.5O19: a road toward diverse applications

The present work aims to synthesize and designate 50% BaFe11.5Co0.5O19 /50% NBR nanocomposite with enhanced physical properties. First, the BaFe11.5Co0.5O19 hexaferrite was successfully synthesized by the citrate auto-combustion technique. Composite nanoparticles were synthesized by melt mixing technique in a Brabender Plasticorder. The structure and morphology of the samples were investigated using X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy (AFM), and scanning electron microscope (SEM). The average crystallite size is nearly 35 nm. The high values of Ms for BFCO can be clarified by Fe3+–O–Fe3+ super-exchange interaction in the present system. An investigation has found that substitution in M-type hexaferrite systems alters the valence states of Fe3+ ions to Fe3+ ions at the 2A sites (Ateia et al. in Appl Phys A 128: 884, 2022). This causes an enhancement of super-exchange interactions that improves the hyperfine field at 2b and 12 k sites. The switching field distribution was computed and reported. Tensile strength (T.S), Young’s modulus (E), hardness (H) and Rheometric characteristics were enhanced after the addition of BFCO nanoparticles to NBR polymer. The obtained data from the present study revealed that the incorporation of 50% of BaFe11.5Co0.5O19 hexaferrite with 50% of NBR rubber enhanced the physico-mechanical and magnetic characteristics of the prepared composites. This indicates that hexaferrites achieve not only appropriate magnetic properties for the prepared composites, but also strengthen the rubber matrix. The originality of this investigation is clarified by emphasizing the magnetization of NBR and to accentuate the good mechanical properties of the investigated nanocomposites.

The Influence of Protein and Elastomer Waste Mixture on the NBR-Based Elastomer Compound

The paper presents the influence of a mixture of elastomeric and protein waste from the footwear industry on the properties of elastomeric compounds based on NBR (butadiene-co-acrylonitrile) rubber, as well as their obtaining and characterization. The mixture of leather and rubber waste was cryogenically ground, in three grinding cycles, and the selected size was 0.35 mm, and the rotation speed of 14,000 rpm. After grinding, the leather and rubber waste mixture was functionalized with potassium oleate at a temperature of 60°C. The polymer compounds based on butadiene-co-acrylonitrile rubber (NBR) and the mixture of protein and elastomeric waste (in the ratio of 15, 20, 40, 50%) from the footwear industry were processed by mixing on an internal Brabender mixer, tested from a rheological, physical and mechanical point of view (hardness, elasticity and tensile strength) after conditioning for 24 h at room temperature according to the standards in force, but also by FT-IR spectroscopy performed with a double beam IR molecular absorption spectrometer, in the range 4000-400 cm-1, using the FT-IR Thermo Nicolet iS 50, equipped with ATR with diamond crystal. Following characterisation, it can be said that they present optimal values that fall within the standards for the footwear industry.

High Performance of Titanium Dioxide Reinforced Acrylonitrile Butadiene Rubber Composites

Recently, dielectric elastomer actuators (DEA) have emerged as one of the most promising materials for use in soft robots. However, DEA needs a high operating voltage and high mechanical properties. By increasing the dielectric constant of elastomeric materials, it is possible to decrease the operating voltage required. Thus, elastomeric composites with a high dielectric constant and strong mechanical properties are of interest. The aim of this research was to investigate the effect of titanium dioxide (TiO2) content ranging from 0 to 110 phr on the cure characteristics, and physical, dielectric, dynamic mechanical, and morphological properties of acrylonitrile butadiene rubber (NBR) composites. The addition of TiO2 reduced the scorch time (ts1) as well as the optimum cure time (tc90) but increased the cure rate index (CRI), minimum torque (ML), maximum torque (MH), and delta torque (MH - ML). The optimal TiO2 content for maximum tensile strength and elongation at break was 90 phr. Tensile strength and elongation at break were increased by 144.8% and 40.1%, respectively, over pure NBR. A significant mechanical property improvement was observed for TiO2-filled composites due to the good dispersion of TiO2 in the NBR matrix, which was confirmed by scanning electron microscopy (SEM). Moreover, incorporating TiO2 filler gave a higher storage modulus, a shift in glass transition temperature (Tg) to a higher temperature, and reduced damping in dynamic mechanical thermal analysis (DMTA). The addition of TiO2 to NBR rubber increased the dielectric constant of the resultant composites in the tested frequency range from 102 to 105 Hz. As a result, TiO2-filled NBR composite has a high potential for dielectric elastomer actuator applications.

Polymer composite based on NBR rubber compounded with rubber waste functionalized with potassium oleate

Waste is a material that occurs as a result of a biological or technological process that can no longer be used as such. Recycling and reusing waste make it possible to contribute to environmental protection and, of course, to the protection of human health by eliminating toxins during waste incineration. The purpose of this paper is to process and characterize polymer composites based on NBR rubber (butadiene-co-acrylonitrile rubber) and rubber waste functionalized with potassium oleate in terms of rheological characteristics (to determine the optimal vulcanization time), Brabender diagrams and physico-mechanical properties in normal state and after accelerated ageing at 70°C, for 168 h (using elastomer-specific equipment). Functionalized rubber waste (with potassium oleate up to 20% at 60°C) is introduced into the mixture in proportions of 10; 20; 30; 50%. The polymeric composites based on butadiene-co-acrylonitrile elastomer and rubber waste (ground with a cryogenic mill at 10,000 rpm, at the size of 0.35 mm) were compounded on a mixer with a capacity of 350 cm3 according to the working recipes. The mixtures were supplemented with vulcanization activators and accelerators on an electric roller, resulting in formulations in the form of 4 mm thick sheets, which are then subjected to the relevant characterizations according to the standards in force for the footwear industry.

CARBOXYLATION OF CELLULOSE-CONTAINING RAW MATERIALS AND ITS USE IN THE COMPOSITION OF LIMITED SWELLING RUBBERS

The purpose of the study is to develop a method for intensifying the process of obtaining a partially carboxylated product based on powdered cellulose from flax straw and to study its effect on the complex of physicomechanical and sorption properties of limited swelling rubbers based on NBR rubber. The paper considers the production of a partially carboxylated product based on powdered cellulose from flax straw. Carboxylated cellulose is used as a heavy metal sorbent, in the oil industry to control the properties of drilling fluids in well drilling, and as a swelling rubber filler for limited swelling rubbers. To intensify the carboxylation process, microwave radiation (MWR) of various powers was used. The carboxylation process was carried out in two stages. At the first stage, cellulose-containing raw materials from flax straw were treated with potassium hydroxide. Next, the calculated amount of monochloroacetic acid was added to the reaction mass. Products with the content of carboxyl groups from 23 to 42 meq have been obtained. It was found that the introduction of carboxylated powdered cellulose from flax straw, as well as powdered cellulose, into the rubber composition makes it possible to maintain the conditional tensile strength of rubbers at the level of the sample without a swelling filler, while the introduction of an industrial product of carboxylated cellulose Na-CMC leads to a significant decrease in the strength of rubber.

Biodegradable polymer composite based on NBR rubber and protein waste

The aim of this work is to characterize a biodegradable polymer composite based on butadiene-co-acrylonitrile rubber (NBR) and protein waste (ground leather). The biodegradable polymer composite was obtained by the mixing technique on a Brabender Plasti-Corder mixer and then on an electric roller (without heating), between its rollers, with sulfur vulcanization activators and Th accelerator, relative to 100 parts plasticized elastomer, obtaining 3-4 mm thick sheets, with strict observance of the technological recipe, but also of the established mode of operation. The obtained mixtures are then subjected to rheological characterization to determine the vulcanization time using the Monsanto rheometer (to determine the optimum temperature and vulcanization times in the laboratory electric press in specific molds for obtaining specimens to be subjected to subsequent characterization). Biodegradable polymeric composites based on butadiene-co-acrylonitrile rubber (NBR) and protein waste (leather waste from the footwear and leather goods industry) were made at optimal working parameters, and the characterization was performed on equipment specific to elastomers and according to standards in force for the footwear and consumer goods industry such as: plates for general purpose footwear soles as well as for water and mud environments, but also for the food industry, car mats, gaskets and components used under normal working conditions, technical plates, insoles, etc.

Modified Archad’s Equation to Estimate Wear Volume due to Sliding Speed

The objective of this research is to introduce a mathematical model of wear volume of Archard’s equation influenced by speed variable. Some researchers have studied the wear volume due to sliding speed, roughness and coefficient of friction. However, mathematical model dealing with sliding speed has never been explicitly reported. Wear analysis is oftenly expressed experimentally through charts concerning both wear volume and sliding speed instead of mathematics. This research is started by modeling mathematical representation within Buckingham Pi Theory. The mathematical parameter contains wear volume, hardness, normal loads, sliding speed, sliding distance, and density of materials. Buckingham Pi model produces three sets of equation. Two of these sets yields Archard’s equation. By combining the third set, the modified Archard’s equation is determined. Since Buckingham set requires a constant of equality, the equation is verified by experiment data. This value is called Wear-Speed Coefficient. Experiment using pin-on-disk tribometer is conducted by varying sliding speed. Further more, those parameters are applied to estimate wear volumes. Materials which are used for this verification are NBR Rubber Nitril, Ultra High Molecular Weight Poly Ethylene (UHMWPE), and Poly Tetra Fluoro Ethylene (PTFE). In conclusion, the modified Archard equation is determined to estimate wear volumes. Based on the experiment, the model is accurate for UHMWPE, NBR and PTFE. Moreover, ratio of density to material’s hardness is significant to control wear resistance influenced by speed.

Mathematical model of wear volumes due to sliding speed using Buckingham Pi Model

The objective of this research is to determine a mathematical model of wear volumes due to sliding speed. Some researchers have studied the influence of sliding speed, roughness and coefficient of friction. However, mathematical model dealing with sliding speed has never been explicitly reported. Wear analysis due to various speed is offenly expressed experimently through charts concerning both wear volume and sliding speed instead of mathematics. This research conducts variables affecting wear. The study is started by modeling mathematical representation within Buckingham Pi Theory. The mathematical model includes wear volume, hardness,normal loads, sliding speed, sliding distance, and density of materials. Since Buckingham set requires constant of equality, the equation is solved by rectifications. The model, in turn, is verified by data gathering to determine the constant. This value is called Wear-Speed Coefficient. Experiment using pin-on-disk tribometer is conducted by varying sliding speed and normal loads. Further more, those parameters are applied to estimate wear volumes. Furthermore, It is compared with those measured data. Moreover, the mathematical model is verified by comparing graphically to results of previous researchers having evaluated wear volumes due to sliding speed. The materials included are 2014 Aluminum Alloy, NBR Rubber Nitril, Ultra High Moleculair Weight Poly Ethylene (UHMWPE), and Poly Tetra Fluoro Ethylene (PTFE). The results of discussion shows that the mathematical approach modelled using Bucking Pi Theory is mostly similar to patterns. This study yields several constants of wear-speed coefficient relating to the materials.

Rubber injection molding: Applying multivariate statistics to identify quality issues solely from process signals

AbstractInjection‐molded rubber parts are widely used in automotive, aeronautical, and industrial engineering applications Therefore, such rubber parts are often critical to the safe operation of the entire system, and part failure can result in significant human or environmental damage. To avoid shipping any parts of subpar quality, manufacturers need to continuously monitor the quality of their product. xIn this work, we apply a principal component analysis (PCA) based process monitoring method. This method is able to detect process fluctuations (faults) in real‐time solely from sensor data features, only requiring pretraining on data from about 10 in‐control cycles. Specific faults were set to critically affect the dynamic performance of the manufactured NBR rubber parts. Fisher discriminant analysis (FDA) was employed to automatically cluster individual molding cycles into those of being in control, those of defectives caused by unfavorable raw material storage and those of out‐of‐tolerance induced by an overheated mold, again solely from sensor data. Both PCA fault detection and FDA fault identification decisions were validated by oscillatory rheology and dynamic compression testing of the manufactured parts. This combined method approach is scalable, transferable, and can be implemented on standard industrial injection molding equipment.

Enhancement of tribological and thermo-mechanical properties of phenolic resin friction composites by improving interactions between elastomeric phase and matrix resin

New elastomer-modified brake friction composites with the identical composition, but differing in the type of rubber, were developed by altering polar/non-polar elastomeric phases into the phenolic resin matrix. Effect of dispersion and interaction of the polar/non-polar rubbers with the matrix resin on dry sliding wear characteristics of the friction composites was investigated using a laboratory-scale pin-on-disc tribometer. The composites were prepared by hot mixing followed by compression molding and post-curing at a high temperature. Coefficient of friction (COF) and specific wear rate of the composites sliding against a cast-iron disc were measured and analyzed. Polar acrylonitrile-butadiene rubber (NBR, both powder, and bale rubber), and non-polar styrene-butadiene rubber (SBR) and ethylene-propylene-diene monomer (EPDM) were used with the phenolic resin where rubber islands and its polarity played the key role in delayed stress dissipation, while the hard matrix phase contributed to the intrinsic strength of the composites. This work describes how the distribution and interaction of polar and non-polar rubbers with the matrix resin influence the performance of brake friction composites. NBR (powder)-phenolic composite showed the highest stable average COF of 0.52 as compared to 0.36 for EPDM-based composite. NBR (powder)-based composite also exhibited ~1.5 times better specific wear rate (4.9 × 10−3 mm3 N−1 m−1) than EPDM-based composite (7.2 × 10−3 mm3 N−1 m−1). However, EPDM rubber-based composite showed a significant enhancement in thermal conductivity (0.43 W/m K). Morphological analyses revealed that the dispersion of rubber phase in phenolic matrix played a significant role in transforming the wear mechanism from abrasive to adhesive.

Electromagnetic shielding response of magnetite elastomeric composites: Source and filler content dependence

The structural and electromagnetic shielding properties of NBR rubber filled with magnetite (Fe3O4) were studied. Rubber composite materials with ore magnetite and synthetic magnetite have been produced separately in order to observe its differences. Samples have been fabricated using a rubber mill and different magnetite ratios. Also, carbon black was added in the same ratio in all samples, not only to improve the mechanical properties of the composites, but also to enhance its dielectric permittivity and reduce its electric resistivity. This kind of composites are used for the manufacture of electronic elements and especially for the production of electromagnetic shielding materials in both passive defense and civil construction applications; buildings, vehicles or airplanes. FESEM-FIB micrographs of the fillers showed the differences in size and shape of the fillers, which influenced the distribution of the particles inside the matrix and therefore the final properties of the composite. Elemental distribution imaging of the composites exhibited the formation of both synthetic magnetite and carbon black aggregates, these structures affect the samples resistivity and the electromagnetic losses due to the conductivity at high frequencies. Electromagnetic shielding properties of the composites were measured in the X-band (8−12 GHz) and K-band of frequency (18–26.5 GHz), all samples showed attenuations greater than −26 dB in both frequency bands. Peaks of maximum attenuation and wider bandwidths were found in the K-band due to the electronic polarization that increased the permittivity of the samples at this high frequency band. The magnetite source (mineral or artificial), its ratio in the rubber matrix and the composite thickness determined the electromagnetic properties of the composite materials.

Dielectrical and electro-mechanical behavior of NBR at high electric field strength

The aim of this work is to present a new approach to characterize the dielectric properties of elastomers especially at low frequencies and high electric field strength, close to the operating conditions of dielectric elastomer actuators (DEA). By means of an electro-rheological measuring cell, static (DC) and alternating (AC) high electric field strength were applied to different types of acrylonitrile-butadiene rubbers (NBR), with varying content of polar acrylonitrile groups. Based on fundamental theory of electricity complex permittivity and polarization were calculated from Coulomb stress measurements at varying frequencies. During high voltage measurements it was observed, that dielectric loss current increases, if a certain critical field strength is exceeded. It is shown, that polar NBR rubbers exhibit a critical field strength far below of the non-polar polybutadiene rubber (BR), acting as a reference sample. NBR exhibits extraordinary high permittivity at low frequency, which makes this material as a favorite candidate for DEA. Furthermore, mechanical properties of NBR can be easily altered by application of an alternating electric field. This phenomenon opens new opportunities in a great variety of applications.

Influence of organic modifier structures of 2D clay layers on thermal stability, flammability and mechanical properties of their rubber nanocomposites

Rubber blends and their nanocomposites based on clay layers were developed. Two different mass ratio of styrene butadiene–nitrile butadiene rubber blend (SBR–NBR) were prepared. Montmorillonite clay modified with methyl dihydroxyethyl hydrogenated tallow ammonium and trimethyl stearyl ammoniums individually were dispersed in SBR–NBR rubber producing different nanocomposites. The mass ratio of organoclay was varied and optimized; also, the dispersion of organoclay sheets was investigated. The mechanical and thermal properties of the developed rubber nanocomposites were studied and improved. The tensile strength of the new nanocomposites was improved recording 16% improvement compared to blank rubber blend. Thermal stability of the developed rubber nanocomposites was enhanced achieving higher 40 °C in decomposition temperature compared to blank rubber blend. Furthermore, the flammability properties of the developed rubber nanocomposites were evaluated and rate of burning achieved 45% reduction compared to blank rubber blend. The chemical structure of organic modifier played an important role in the final nanocomposites performance. The intercalation of dispersed organoclay sheets with rubber blend was elucidated using X-ray diffraction and dispersion was confirmed using SEM.

An experimental investigation of laser drilling nitrile butadine (NBR) rubber

This paper focusses on understanding laser-NBR rubber interactions in particular the effect of laser wavelength and pulse width on material removal and thermal damage. Three lasers with wavelengths at 355 nm, 795 nm and 1064 nm and pulse duration at 30 ns, 10 ps and 130 fs, respectively, have been investigated for their optical absorption, heat conduction and their material removal mechanisms in high aspect ratio drilling of NBR rubber. It is interesting to find that under certain conditions, the ultrashort pulse lasers (both the femtosecond and picosecond lasers) did not lead to better results than the nanosecond UV laser in drilling hole profile (straightness and thermal damage), aspect ratio and amount of the ablated material re-deposition on the substrate surfaces. The results implied that there is heat conduction and thermal damage even with ultrashort laser pulses when the processing conditions are not appropriate. Firing laser pulses intermittently was shown to reduce thermal accumulation. Experimental studies showed that the 355-nm Nd:YAG laser (UV laser) achieved higher material removal rate with high aspect ratio as compared to the ultrashort laser pulses in drilling the NBR substrates.