Neat NBR Research Articles

Nanocellulose-triggered structural and property changes of acrylonitrile-butadiene rubber films

In this study, the effect of cellulose nanocrystals (CNCs) incorporation on the structure–properties of acrylonitrile-butadiene rubber (NBR films), with particular focus on curing enhancement and reinforcing potential, was investigated. The NBR crosslinking efficiency, observed from nuclear magnetic resonance analysis, increased with successive CNC concentration increases due to better dispersion of ZnO from Zn-cellulose complex formation. Energy dispersive X-ray and transmission electron microscope analysis of the films revealed increasingly well-dispersed ZnO with increasing CNC. The increase in the crosslinking density in conjuncture with the reinforcing capability of CNCs resulted in increases in the tensile strength, stiffness, toughness, tear strength and elongation by 203, 8300, 664, 179, and 14%, respectively for films containing 3 phr CNC compared to the neat NBR. The incorporation of 0.5 phr CNC reduced the water absorption of neat CNC by 250%. Overall, water absorption of the nanocomposite films was considerably lower than that of the neat NBR through CNC consolidation of the rubber particles by reducing free volume in the NBR structure. The nanocomposite films show promise for glove and other dipped product applications where improved tear resistance and overall physical properties improvement are needed without compromising the integrity.

Mechanical Strength Improvement of Mud Motor’s Elastomer by Nano Clay and Prediction the Working Life via Strain Energy

In directional drilling, the most important thing that leads to pulling out the drill string is end of mud motor working life. Considering the working conditions of down hole mud motors; increasing the mechanical properties of their stator’s elastomer is crucial. Some attempts were done to increase the motor performance through geometrical changes but lack of material improvement is significant in previous studies. In this study, NBR/nanoclay composite samples were prepared through melt intercalation in an internal mixer and tested with regard to the temperature and drilling mud of down hole. Hardness, tear, fatigue and tensile test results of neat NBR elastomer and nanocomposite of NBR and different loading of nanoclay showed that the mechanical strength of new composites are considerably increased. With the help of strain energy method it was revealed that the life of NBR/nanoclay composite compared to neat NBR was enhanced. Therefore, increasing the working life and performance of the motor is achievable by using this nanocomposite. In the drilling industry, there is a direct relation between time and cost; therefore, increasing the working life of the motor leads to a considerable cost reduction in this expensive industry.

Polyesteramidesulfone as novel reinforcement and antioxidant nanofiller for NBR blended with reclaimed natural rubber

Abstract In this study, we exploited the addition of reclaimed natural rubber waste (NRr) in acrylonitrile butadiene rubber (NBR) to develop a cost-effective rubber blend based on 92 phr NBR and 8 phr NRr. The mechanical properties of the blend were enhanced by using new reinforcement nanofiller synthesized by condensation reaction between terephthaloyl chloride (TPC) with bis(4-aminophenyl) sulfone (BAPS) and bisphenol S. Polyesteramidesulfone (PEAS) was produced and well characterized using different analytical tools such as; FTIR, H NMR, DSC, TGA, TEM, and GPC. The TEM image of PEAS showed nano irregular-shaped particles. PEAS was mixed with NBR and NBR/NRr blend in different loading levels, (1.5, 3 and 6 pphr) to prepare NBR/PEAS and NBR/NRr/PEAS vulcanizates. The tensile strength, elongation at break, equilibrium swelling, crosslinking density, thermo-oxidative aging test, FTIR, TGA, and SEM of the rubber vulcanizates were measured. Fractured morphology was detected in SEM images by the partial replacement of NBR with NRr leading to a decrease in the tensile strength and elongation at break of NBR/NRr vulcanizate than neat NBR. However, the addition of PEAS improved the compatibility between NBR and NRr and increased the cross-linked structure of NBR chains through physical links leading to increase the tensile strength and decrease the elongation of the vulcanizates. The low molecular weight of NRr and the degradation of amide and ester groups of PEAS lowered the thermal stability of their vulcanizates up to 420 °C than neat NBR. Loading of PEAS in NBR and NBR/NRr caused an increase in their glass transition temperature. The rate of reduction in tensile strength up to 7 days is much lower in vulcanizates loaded with PEAS than those without. It was concluded that PEAS played dual function in NBR and rubber blends as an antioxidant and reinforcement nanofiller.

7Effects on Thermal and Ablative Properties of Phenolic Resin (Novolac) Blended Acrylonitrile Butadiene Rubber

In this work we investigated the ablative response and thermal properties of phenolic resin (PR) blended acrylonitrile butadiene rubber (NBR) composites. PR was added to NBR in the proportion of 0, 5, 10, 20, 30, 40 and 50 phr by means of two-roll laboratory mill. PR remarkably improved ablation resistance and thermal properties of NBR/PR composite. The linear and mass ablation rates reduced to 21.3 % and 26.1 % respectively. The char content deposition increased from 0.19 to 26.8 %. Char layer produced by PR, obviously reduced the erosion rate of the NBR/PR composite relative to neat NBR (without PR). Detailed morphological studies of the composite and post-test (ablation) microstructure of char revealed that higher loading of PR in the rubber composite produced dense char layer firmly intact to the substrate. Furthermore, thermal stability of the composite improved by 22–23 oC, however, thermal conductivity of the composite slightly increased by 0.115 W/mK for 50 Phr of PR loading as compared to the neat.

Chemical modification of nitrile rubber in the latex stage by functionalizing phosphorylated cardanol prepolymer: A bio-based plasticizer and a renewable resource

The present investigation deals with the functionalization of acrylonitrile butadiene rubber (NBR) by chemically grafting phosphorylated cardanol prepolymer (PCP) onto its backbone chain. The grafting of PCP onto NBR was accomplished in the latex stage successfully using benzoyl peroxide as the free radical initiator. The functionalized NBR (PCP- g-NBR) is characterized by ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and gel permeation chromatography. PCP- g-NBR exhibited an increase in molecular weight (4.4%) with an increase in the polydispersity. The grafting parameters have been optimized using “Taguchi L9table” and the optimum conditions were found to be “3 phr of initiator concentration, 15 phr of the PCP concentration, reaction temperature of 70°C and reaction time of 6 h.” The percentage grafting and grafting efficiency were calculated to be 7.28 and 80.37%, respectively, under optimum processing conditions. The PCP- g-NBR exhibited a reduction in Wallace plasticity number as well as the Mooney viscosity and an enhanced plasticity retention index (PRI) as compared to neat NBR. The rheological measurements exhibited a higher flow behavior index for PCP- g-NBR than the NBR itself. Differential scanning calorimetry and dynamic mechanical analysis results exhibited a decrease in glass transition temperature on functionalization of NBR confirming enhanced plasticization. Thermogravimetric analysis results displayed an increase in thermal stability of the functionalized NBR than that of virgin NBR. The physico-mechanical properties of the PCP- g-NBR vulcanizates were at par with or even better than the neat NBR vulcanizates. 3-(4,5-Dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide assay and hemolysis studies indicated NBR and PCP- g-NBR are nontoxic and biocompatible.

Influence of melamine formaldehyde microsphere on the vulcanization kinetics and mechanical properties of nitrile butadiene rubber

The melamine formaldehyde (MF) microsphere/nitrile butadiene rubber (NBR) vulcanizates were prepared by adding MF into NBR through mechanical mixing, followed by a vulcanization process. The influences of MF on the vulcanization characteristics, vulcanization kinetics, and mechanical properties were investigated. The results showed that MF interacted with NBR through hydrogen bonds. In addition, parameter b calculated by the ratio of modulus and strains also demonstrated the strong interaction between MF and NBR. Adding MF into NBR would reduce the curing time of NBR compounds, and increase the curing rate, as well as the cross-linked density. The vulcanization kinetics of MF/NBR compounds could be simulated accurately by Ghoreishy’s model. The mechanical properties of MF/NBR increased with the incorporation of MF. The modulus at 100%, modulus at 300%, and tensile strength of NBR vulcanizates with 20 parts per hundred rubber MF had 155, 90, and 110% increment, respectively, compared with those of neat NBR. The MF also enhanced the tear strength of NBR by 80% with a rough tear-fractured surface of NBR recorded by scanning electron microscope.

High dielectric acrylonitrile-butadiene rubber with excellent mechanical properties by filling with surface-modified barium/strontium inorganic functional powders

Acrylonitrile-butadiene rubber (NBR) filled with surface-modified barium titanate (MBT), strontium titanate (MST) and barium strontium titanate (MBxS1−xT) was used to prepare the polymer dielectrics. BxS1−xT powders (x = 0.8, 0.7, 0.5 and 0.3) were synthesized via solid-state method. The crystal structure was observed by X-ray diffraction. The morphology and particle size of different powders were characterized by scanning electron microscopy (SEM). The contact angle test verified the hydrophobicity of the inorganic functional powders modified with bis-(γ-triethoxysilylpropyl)-tetrasulfide (KH845-4) improved obviously. The ratio of the dispersive solid surface tension and polar solid surface tension between inorganic filler and NBR matrix became closer after surface modification. The NBR/MBT/MST and NBR/MBxS1−xT systems were designed to improve the dielectric properties and enhance the mechanical properties. The curing characteristic of all NBR gums was tested. The dispersion of surface-modified functional filler in NBR was observed great according to the images of SEM. The mechanical properties of NBR/filler composites reinforced markedly compared with the neat NBR. For dielectric properties, the NBR/MB0.7S0.3T composites had the highest dielectric constant and the NBR/MST composites had the lowest dielectric loss factor at room temperature. They were suitable to be applied under the different frequency in oily environment for a long time. The oil resistance of all composites was also tested.

Compatibilizer effect on Organosilicate reinforced NBR nanocomposites

Nanocomposites of intercalated and exfoliated organosilicates in acrylonitrile butadiene rubber (NBR) were prepared by a two-stage melt blending method. The dispersion and interlayer space of organosilicates in these nanocomposites were examined by X-ray diffraction, transmission electron microscopy and field emission scanning electron microscopy. Dramatic enhancements in the mechanical and thermal properties of NBR were found by incorporating less than ten parts of organosilicates. In particular, the addition of 10 phr of the organosilicate in NBR provided more than a 360% increase in tensile strength, a two-fold increase in M500, a 93% increase in tear strength and a relative enhancement in elongation at break, as compared to the neat NBR. The degradation temperature for NBR with ten parts loading of organosilicate was 25 °C higher than that of the neat NBR. In addition, the relative vapor permeability of nanocomposites containing 15 phr of layered silicates was reduced, as compared to the neat NBR.

Enhancement of mechanical strength associated with interfacial tension between barium titanate and acrylonitrile–butadiene rubber with different acrylonitrile contents by surface modification

ABSTRACTAcrylonitrile–butadiene rubber (NBR) with different acrylonitrile (ACN) contents was filled with barium titanate (BT) to prepare the polymer dielectrics. The neat NBR, NBR/untreated BT, and NBR/bis‐(γ‐triethoxysilylpropyl)‐tetrasulfide (silane coupling agent KH845‐4) modified BT (MBT) composites were prepared. At low ACN content (ACN content 20 wt %), the tensile strength of the NBR/MBT composites increased by 173.6% from 2.69 to 7.36 MPa compared to the neat NBR. The pleasing results were not found in those composites with high ACN content. Both surface modifications of BT and NBR with low ACN content would result in lower interfacial tension between BT and NBR. A strong interfacial adhesion was observed between MBT and NBR with 20 wt % ACN content. The interfacial adhesion had great contribution to the mechanical strength of composites. Moreover, the dielectric properties of composites were also investigated in detail. The addition of BT enhanced the dielectric constant of composites markedly. This study can be applied in manufacturing electronic devices, which are subjected to oily environments for a long time. At the same time, the study can provide some help for researchers to select the polymer matrix and the appropriate surface modification agent of functional filler. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45936.

Elastomer reinforcement by graphene nanoplatelets and synergistic improvements of electrical and mechanical properties of composites by hybrid nano fillers of graphene-carbon black & graphene-MWCNT

Present work deals with the reinforcement behaviour of graphene nanoplatelets (GNP) in elastomer matrix of acrylonitrile butadiene (NBR) co-polymer. The addition of 20phr GNP in NBR matrix a significant improvement in tensile strength (∼528%), and elongation at break (∼60%) compared to neat NBR is observed. Hybrid composites of NBR filled with GNP-CB and GNP-MWCNT at judicious proportion exhibit further improvement in the mentioned properties compared to those exhibited by composites containing individual fillers at same loading. This reflects strong synergistic effect on properties by hybrid fillers. Morphological studies reveal the state of dispersion of filler in matrix polymer, and this can be correlated with property improvements. The better synergistic effect of GNP-CB hybrid filler in comparison to GNP-MWCNT for improvement in mechanical and electrical properties as well as thermal stability may be attributed to the better filler dispersion and higher polymer-filler interaction for NBR-GNP-CB hybrid system compared to NBR-GNP-MWCNT system.

Polyvinylidene Fluoride/Acrylonitrile Butadiene Rubber Blends Prepared Via Dynamic Vulcanization

Dynamically vulcanized blends based on polyvinylidene fluoride (PVDF)/acrylonitrile butadiene rubber (NBR) were prepared and characterized. The mixing torque and dynamic rheology analyses showed that the NBR phase increased the viscosity of the blends. Scanning electron microscopy (SEM) results showed that the NBR phase was in the form of spherical particles dispersed in the PVDF phase during dynamic vulcanization. Comparing PVDF-rich and NBR-rich blends, the size of the rubber particles in the NBR-rich blends were larger than those in PVDF-rich blends. Differential scanning calorimetry (DSC) results showed that the addition of the NBR phase reduced the PVDF crystallinity and Tm. Thermal gravimetric analysis (TGA) results showed that the dynamically vulcanized PVDF/NBR blends had a higher residual char mass than the neat PVDF and NBR. For PVDF-rich blends, the PVDF can be highly toughened by NBR; the Izod impact strength of the PVDF/NBR (70/30) blend was 77.5 kJ/m2, which was about six times higher than that of pure PVDF. For rubber-rich blends, the PVDF component was beneficial to the mechanical properties of the blends, which can be used as thermoplastic elastomers.

Novel one‐step synthesis of acrylonitrile butadiene rubber/bentonite nanocomposites with (3‐Mercaptopropyl)trimethoxysilane as a compatilizer

Acrylonitrile butadiene rubber (NBR)/bentonite (Bt) nanocomposites were synthesized by an one‐step method in NBR latex with (3‐Mercaptopropyl)trimethoxysilane (MPTMS) as a compatilizer. The nanocomposites were compounded with curing additives and then vulcanized. The prepared vulcanizates were characterized by Fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD). The curing properties and mechanical properties were also investigated. The thermal properties were studied with thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The morphology was investigated by field emission‐scanning electron microscopy (FE‐SEM). By swelling test, the swelling ratio and the crosslinking density were achieved. The hydrolyzation and condensation of MPTMS was identified by FTIR while the intercalated/exfoliated structure of Bt was determined by XRD. It was evident that the mechanical properties of the nanocomposites were significantly improved compared with the neat NBR. The well‐dispersed bentonite particles and effects of MPTMS were supported by the images from FE‐SEM. The results of TGA showed that the fastest weight‐loss temperature (Tmax) was elevated by over 10°C for the nanocomposites compared with the neat NBR, indicating an enhanced thermal stability. By swelling test, the swelling ratio was determined, decreased to 139% for the optimized NBR/MPTMS/Bt nanocomposites compared with 210% for neat NBR. POLYM. COMPOS., 36:1693–1702, 2015. © 2014 Society of Plastics Engineers

Acrylonitrile–butadiene rubber functionalization for the toughening modification of recycled poly(ethylene terephthalate)

ABSTRACTThe incorporation of functionalized acrylonitrile–butadiene rubber (NBR) into recycled poly(ethylene terephthalate) (PET) was introduced as an effective route for modifying the properties of PET and as a new method for PET recycling as well. To achieve modified NBR, glycidyl methacrylate (GMA) was grafted onto NBR with optimized reactive mixing, in which the highest grafting degree and lowest gel content were generated. PET/NBR blends with and without GMA functionalization were produced by melt mixing, and the mechanical properties, dynamic mechanical thermal properties, and phase morphologies of the systems were determined and compared. We found that low amounts of peroxide initiator (dicumyl peroxide) and high levels of the GMA monomer in the presence of the styrene comonomer led to the maximum grafting degree and suppressed the competing rubber crosslinking and GMA homopolymerization reactions. The blend compatibility with PET determined from dynamic mechanical thermal analysis spectra and scanning electron microscopy images was greatly improved when the NBR‐grafted GMA was used instead of the neat NBR in the blend recipes. As a result, the rubber phase dispersed in the PET matrix more finely, and the impact strength of the blend advanced very significantly. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40483.

Evaluation of Effect of Various Nanofillers on Technological Properties of NBR/NR Blend Vulcanized Using BIAT-CBS System

Owing to processing ease and resistance to oils and chemicals, NBR is widely used in many industries. But since neat NBR has only poor tensile properties, it is better to use suitable blends of NR and NBR after incorporating appropriate nanoingredients before vulcanization. It is well established that nanoparticles can be easily dispersed in a more uniform pattern in polymer matrix, thereby enhancing the technological properties of the elastomer vulcanizate. Since there are no systematic comparative studies on technological properties of NBR/NR blend containing different nanoingredients, efforts have been made in this study to investigate cure and technological properties like tensile properties, tear resistance, compression set, hardness, abrasion loss and swelling value of NBR/NR (80/20) blend vulcanizates containing stearic acid-coated nano-zinc oxide (ZOS), nano-BIAT, nano-silicate-coated CaCO3, PEO-coated calcium silicate, and surface-modified carbon nanotubes (CNT). XRD and electron microscopy have been used for morphological analysis. The nano ingredients were effective in enhancing the technological properties of the vulcanizates. Among the nanofillers, modified CNT was found to impart superior properties to NBR/NR blend due to more intercalation.

Mechanical, thermal, and transport properties of nitrile rubber–nanocalcium carbonate composites

AbstractThe article describes the properties of acrylonitrile butadiene copolymer (NBR)–nanocalcium carbonate (NCC) nanocomposites prepared by a two‐step method. The amount of NCC was varied from 2 phr to 10 phr. Cure characteristics, mechanical properties, dynamic mechanical properties, thermal behavior, and transport properties of NBR–NCC composites were evaluated. For preparing NBR nanocomposites, a master batch of NBR and NCC was initially made using internal mixer. Neat NBR and the NBR–NCC masterbatch was compounded with other compounding ingredients on a two roll mill. NCC activated cure reaction upto 5 phr. The tensile strength increased with the nanofiller content, whereas NBR–NCC containing 7.5 phr exhibited the highest modulus. The storage modulus (E′) increased up to 5 phr NCC loading; the reinforcing effect of NCC was seen in the increase of modulus which was more significant at temperatures above Tg. The effect of nanofiller content and temperature on transport properties was evaluated. The solvent uptake decreased with NCC content. The mechanism of diffusion of solvent through the nanocomposites was found to be Fickian. Transport parameters like diffusion, sorption, and permeation constants were determined and found to decrease with nanofiller content, the minimum value being at 7.5 phr. Thermodynamic constants such as enthalpy and activation energy were also evaluated. The dependence of various properties on NCC was supported by morphological analysis using transmission electron microscopy. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Studies on acrylonitrile—butadiene copolymer (NBR) layered silicate composites: mechanical and viscoelastic properties

Nanocomposites were obtained from a masterbatch of acrylonitrile—butadiene copolymer (NBR; nitrile rubber) and organomodified layered silicate (nanoclay) prepared in an internal mixer followed by mixing with neat NBR and other compounding ingredients on a two-roll mill. Addition of nanoclay reduced the cure time and the vulcanization kinetics closely fitted a first-order model. The morphology was investigated by X-ray diffraction and transmission electron microscopy. The tensile strength, modulus (M100), and storage modulus (E') increased up to 5-phr nanoclay content and thereafter showed a decline. The effect of temperature and frequency on E' and loss tangent was also investigated.