NBR Nanocomposites Research Articles

Dual influence of graphene oxide/clay and electron beam radiation on the structure, mechanical, thermal, and antimicrobial properties of nitrile butadiene rubber nanocomposite

Infective diseases are becoming more popular, and managing them has become a great worry for humanity. A rubber nanocomposite based on nitrile butadiene rubber with graphene oxide (NBR/GO) and GO/nanoclay (montmorillonite, MMT) (NBR/GO/MMT) was fabricated by a simple technique, roll milling. The synergistic influence of the existence of GO, clay, and electron beam (EB)-radiation on the NBR nanocomposites was characterized using scanning electron microscopy (SEM), and Fourier-transform infrared (FT–IR) techniques to study the mechanical, thermal, and antibacterial properties. The antibacterial activity of the prepared rubber nanocomposites was estimated via the disk diffusion process against Gram-positive bacteria, Bacillus subtilis, Staphylococcus lentus, and Gram-negative bacteria ; Pseudomonas aeruginosa and Proteus mirabilis. The results demonstrated that the physico-mechanical performance was significantly reinforced by incorporating nano GO (6 phr) and clay with GO (3 phr/6 phr. NBR films have no antibacterial potential. GO increases the antibacterial efficiency of the NBR films. NBR/3% GO/3% clay film is the most effective in reducing bacterial growth and B. subtilis was the most sensitive bacteria for rubber treatments. The inhibition zone diameters of the un-irradiated and irradiated NBR/3% GO/3% clay films for B. subtilis were 18.03 ± 0.59 and 25.63 ± 0.98 mm, respectively. It could be concluded that because of its outstanding flexibility and human-body compatibility penetration, rubber in corporation with antimicrobial agents can be utilized for manufacturing medical and environmental products.

Nano-lithium ferrite/nanosilica-filled butadiene-acrylonitrile rubber for microwave absorption

Recently, the development of flexible and lightweight microwave-absorbing materials has become a trendy topic. Hence, the principal aim of this work is to enhance the microwave-absorbing performance of butadiene-acrylonitrile rubber (NBR) by incorporating novel reinforcing nanofillers. Cost-effective nano-lithium ferrite/nanosilica is synthesized via the precipitation of two thin layers of lithium ferrite with thicknesses of 10 and 20 % on the surface of cheap nanosilica extracted from rice husk agro-waste. To achieve optimal microwave-absorbing performance, both LiFe 10 %/Si and LiFe 20 %/Si NPs were incorporated into the NBR matrix at various loadings (2, 4, 8, and 16 parts per hundred rubber (phr)). Several investigations were performed on the NBR nanocomposites to explore their morphology, curing behavior, mechanical, equilibrium swelling, magnetic properties, and microwave-absorbing behavior. The mechanical characteristics of NBR nanocomposites reveal that the inclusion of LiFe/Si NPs enhanced their modulus, tensile strength, and elongation at break while reducing their hardness. Moreover, the obtained findings clarify that the 16 phr (LiFe 20 %/Si) filled-NBR nanocomposite has superior microwave-absorbing performance with a maximum absorption bandwidth of 2.2 GHz. Overall results reveal that the novel lithium ferrite/silica nanoparticles could be an effective filler for enhancing the microwave absorption efficiency of NBR nanocomposites. Thus, this research suggests a novel viewpoint on the fabrication of flexible microwave-absorbing materials.

PHYSICO-MECHANICAL AND DYNAMIC MECHANICAL PROPERTIES OF META-PENTADECENYL PHENOL FUNCTIONALIZED ACRYLONITRILE–BUTADIENE RUBBER NANOCLAY COMPOSITES

ABSTRACT The physico-mechanical and thermo-mechanical properties of meta-pentadecenyl phenol (cardanol) functionalized acrylonitrile–butadiene rubber (CGNBR) composites containing sodium montmorillonite clay were determined via studies on the functionalization of NBR by grafting cardanol onto its backbone main chain in the latex stage using benzoyl peroxide as a free radical initiator. Results show an improvement in technical properties for functionalized NBR nanocomposites over the NBR nanocomposite. Air and ASTM 3 oil aging studies at 100 °C confirmed an increase in tensile strength and a decrease in elongation at break for CGNBR compared to the dioctyl phthalate plasticized NBR nanocomposite. Fire and flame retardancy studies showed an increased limiting oxygen index for functionalized NBR over the NBR nanoclay composite. Results delineate the method of preparation and characterization of functionalized NBR and oil plasticized NBR nanoclay composites to achieve an improved oil resistance effect for functionalized NBR over NBR nanocomposite.

Effect of in situ silanization of multiwalled carbon nanotubes on the properties of NBR/MWCNT-OH composites

ABSTRACTThis paper presents the preparation and properties of improved acrylonitrile-butadiene rubber (NBR) composites with hydroxylated carbon nanotubes (MWCNT-OH). A series of in situ modifications were performed using [3-(2-aminoethylamino)propyl]trimethoxysilane (APTS), vinyltrimethoxysilane (VTS) and (3-mercaptopropyl)trimethoxysilane (MPTS). The curing behavior, crosslink density, static and dynamic mechanical properties (DMTA), filler-filler interactions (Payne effect), thermal stability (TGA) and aging stability of the NBR nanocomposites were investigated, in addition to morphological studies (SEM/EDS). The experimental data prove that the most promising silane agent stongly affecting the properties of NBR/MWCNT-OH composite systems was APTS. The NBR vulcanizates showed increased torque, crosslink density, dynamic moduli and tensile strength.

Preparation and properties evaluation of nitrile rubber nanocomposites reinforced with organo-clay, CaCO3, and SiO2 nanofillers

Acrylonitrile butadiene rubber (NBR)-based nanocomposites reinforced with organo-clay, calcium carbonate, and silica as nanofillers with different contents ranging from 1 to 10 phr (part per hundred parts of rubber) were prepared and characterized. Surface modification was done on the clay nanoparticles to intensify the formation of chemical bond between nanofiller and NBR matrix. A novel procedure and formula were implemented to fabricate considered composites and nanocomposites. Variety of tests and analyzes were done on all nanofillers and fabricated nanocomposites and accordingly, curing conditions, mechanical and chemical properties of the resulting NBR nanocomposites intercalated with nanofillers were further improved and optimized. The nanocomposite containing 10 phr of nanoorgano-clay were found to be the best choice among other synthesized nanocomposites in the case of improved curing conditions, mechanical, and chemical properties.

Influence of Ion Beam and Carbon Black Filler Type on the Mechanical and Physico-Chemical Properties of Butadiene Acrylonitrile Rubber (NBR)

Five types of carbon black nanofillers, namely Intermediate Super-Abrasion Furnace ISAF (N220), High-Abrasion Furnace HAF-LS (N326), Fast Extruding Furnace FEF (N550), General Purpose Furnace GPF (N660) and Semi-Reinforcing Furnace SRF-HS (N774) were incorporated with butadiene acrylonitrile rubber (NBR) in order to improve its physical properties. Young's modulus was found to increase with nanofiller content. Percolation concentration was detected in mechanical as well as in Physico-chemical behavior. The experimental values of the normalized Young's modulus fit well with Pukanszky et al. model; taking into consideration the difference in carbon black-filler type. It is noticed that the characteristic time of swelling in toluene, τ is higher for NBR loaded with 30 phr ISAF and for the rest of samples it increases with increasing of particle size. Finally oxygen ion beam irradiation for percolative loading NBR nanocomposites increases Young's modulus nearly by 2-3 times.

Studies on the Mechanical Properties of Carbon Black/Halloysite Nanotube Hybrid Fillers in Nitrile Rubber Nanocomposites

Carbon black (CB)-Halloysite nanotubes(HNT) hybrid composites based on Acrylonitrile Butadiene rubber(NBR) were prepared. The Carbon black loading was kept fixed at 60 phr and Halloysite nanotube loading was varied from 0 to 10 parts per hundred rubber(phr). The nanocomposites were prepared by mixing using a two-roll open mill. The effect of CB-HNT hybrid fillers on the curing behaviour, mechanical properties and morphology of the NBR nanocomposites was investigated. The cure characteristics showed that the scorch time(ts2) and cure time (t 90) increased with the HNT loading. The maximum torque(MH) exhibited an increasing trend from 0 to 6 phr . The tensile properties which exhibited an increasing trend until an optimum loading of 6phr were mainly influenced by the NBR-CB-HNT interaction and the intercalation of rubber and CB into the tubules. These results were well supported by the XRD studies and cross link density determinations.

Effect of sol–gel modified nano calcium carbonate (CaCO3) on the cure, mechanical and thermal properties of acrylonitrile butadiene rubber (NBR) nanocomposites

The main goal of this work is to modify surface of nano CaCO3 with silica by an elegant approach of sol–gel method and also to compare the influence of sol–gel modified nano CaCO3 with unmodified nano CaCO3 in the cure, mechanical and thermal properties of acrylonitrile butadiene rubber (NBR) nanocomposites. The surface modification of nano CaCO3 is characterized by Fourier transform infrared spectra and Field emission scanning electron microscopy. The modified nano CaCO3 causes significant improvement in the maximum rheometric torque (R∞) and cure rate index value of NBR nanocomposites in comparison to unmodified nano CaCO3. More importantly, incorporation of surface modified nano CaCO3 provides substantial enhancement in the mechanical properties of NBR nanocomposites and at 4 phr (parts per hundred parts of rubber) filler loading level tensile strength of modified nano CaCO3 filled NBR vulcanizate shows a large increment by 37.33 % compare to that of unmodified nano CaCO3 filled NBR vulcanizate. Thermogravimetric analysis reveals that sol–gel modified nano CaCO3 delivers greater thermal stability in NBR nanocomposites than unmodified nano CaCO3. The fantastic enrichment in the cure, mechanical and thermal properties of NBR nanocomposites containing surface modified nano CaCO3 will be the part of great interest for rubber researcher regarding the broad application of sol–gel modified nano CaCO3 as important filler in rubber industry.

Payne effect in NBR nanocomposites with organofilic montmorillonite

Payne effect in NBR nanocomposites with organofilic montmorillonite

The influence of zinc ferrites nanoparticles on the thermal, mechanical, and magnetic properties of rubber nanocomposites

AbstractThe interest to ferrite nanoparticles (NPs) is thriving because of their unique applications in life industry. Doping of rubber composites by nanoparticles results in a novel characteristics which is not exist either in the ferrite or rubber alone. In this study, zinc ferrite NPs have been synthesized via sol–gel technique. These nanoferrites embedded into acrylonitrile butadiene rubber (NBR) at different concentrations. The morphology and structure of zinc ferrite and zinc ferrite NPs doped NBR were investigated using X‐ray diffraction and transmission electron microscopy. The influence of zinc ferrite NPs loading on the thermal stability showed that the zinc ferrite enhanced the thermal stability and reduced the rate of thermal degradation of rubber nanocomposites. The effect of zinc ferrite NPs on the mechanical properties of NBR showed that the hardness, tear strength, and tensile stress are improved. The magnetic measurements of these nanocomposites showed that the saturation magnetization is enhanced as the concentration of zinc ferrite NPs increased into NBR nanocomposites. The EPR spectra of zinc ferrite NPs doped NBR indicated that the increase in zinc ferrite NPs content resulted in an increase in the g‐factor and line width. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

Effect of ionizing radiation on the properties of acrylonitrile butadiene rubber/clay nanocomposites

The effects of electron beam irradiation dose (50–150 kGy) and the concentration of montmorillonite (MMT) clay (3–10 parts per hundred part of rubber (phr)) on the properties of acrylonitrile butadiene rubber (NBR) have been investigated. The dispersion of the layered silicates was assessed by x-ray diffraction and transmission electron microscopy. The morphology of NBR nanocomposites showed exfoliated clay layers at low clay content and a combination of exfoliated and intercalated clay layers at high clay content. The mechanical properties of NBR composites such as tensile strength (TS) and tear strength were remarkably improved by the incorporation of organoclay and electron beam irradiation, while elongation at break ( Eb) was decreased. The increase in the TS of NBR nanocomposites increases with the increase in the clay content up to 10 phr, whereas the optimum gel content and TS of NBR composites were observed at 50 kGy irradiation dose. Thermogravimetric analysis studies showed that NBR/organo-MMT nanocomposites have higher decomposition temperatures in comparison with the NBR/Na+-MMT at 50 kGy irradiation dose.

Radiation induced modification of NBR and SBR montmorillonite nanocomposites

Nanocomposites of two different kinds of rubber (acrylonitrile-butadiene rubber NBR and styrene butadiene rubber SBR)/organo-montmorillonite nanocomposites modified by hexadecyltrimethyl ammonium bromide were prepared by the reactive mixing intercalation method in the presence of trimethylolpropane trimethylmethacrylate (TMPTMA). The influence of gamma irradiation on the morphology and properties of the rubber nanocomposites was investigated. Intercalated polar or unsaturated matrices (e.g., NBR and SBR)/OMMT nanocomposites can be obtained, which was confirmed by X-ray diffraction (XRD). The clay layers could be uniformly dispersed in the rubber matrix on the nanometer level. Mechanical tests showed that the nanocomposites had good mechanical properties as compared to the neat composites. The results also showed that the irradiated NBR/OMMT nanocomposites had higher thermal stabilities than irradiated SBR/OMMT nanocomposites.

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

A comparative study on curing characteristics and thermomechanical properties of elastomeric nanocomposites: The effects of eggshell and calcium carbonate nanofillers

AbstractAfter‐hatching eggshell (AHES) nanobiofiller and nanocalcium carbonate (nano‐CA) were separately added to various elastomers, such as acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), and natural rubber (NR), in various amounts of 5, 10, and 15 phr. The effect of particle size and dispersion of such nanofillers on thermomechanical properties and curing characteristics were then investigated. The ultimate tensile properties of SBR and NR nanocomposites were improved to some extent when 5 phr of AHES nanofiller was added to the rubber compound compared to CA. In the case of NBR nanocompounds, however, the mechanical properties were seemingly comparable, irrespective of the type of nanofiller. This contradictive behavior could be attributed to the alteration of crosslink density due to particular filler–matrix interaction while using mineral and natural fillers. The results of the rheometric study revealed that using AHES rather than CA slightly increases the scorch time of all types of prepared nanocomposites, whereas a significant drop in the optimum curing time was seen for NBR nanocomposites containing AHES biofiller. Moreover, thermogravimetric analysis showed similar thermal stability for SBR nanocomposites containing AHES and CA fillers. Finer particle size of CA and higher porosity of AHES at high and low loading levels were respectively the main reasons for improvement of ultimate properties. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

MODELING AND OPTIMIZING PROPERTIES OF NANOCLAY–NITRILE RUBBER COMPOSITES USING BOX–BEHNKEN DESIGN

Abstract The mechanical behavior of acrylonitrile butadiene copolymer (NBR)–organomodified layered silicate (nanoclay) was modeled using design of experiments approach. A Box–Behnken design with three factors and three levels was used to model the relationship between properties of NBR nanocomposites and the ingredients. The factors considered in the design were silica content, nanoclay loading, and dicumyl peroxide content. The nanocomposites were evaluated for tensile strength, modulus, elongation at break, oxygen permeation rate, and effect of oil and heat aging on mechanical properties. Regression equations were generated to model the properties of interest and generate response surfaces and contour plots. The predicted properties of the nanocomposites were in good agreement with the experimental results. The contour plots were overlaid within the applied constraints to identify the combination of factor ranges that gives the optimal performance of the nanocomposites for application as control system bladders in satellite launch vehicles.

Modeling of chemical kinetics of elastomer/hydroxyl‐ and carboxyl‐functionalized multiwalled carbon nanotubes nanocomposites' cross‐linking

AbstractSeveral kinds of (hydrogenated) nitrile elastomer ((H)NBR) compounds were prepared by melt compounding of rubbers with carbon nanotubes. Transmission electron microscopy (TEM) showed that the exfoliation degree of nanotubes was high. Multiwalled carbon nanotubes (MWCNT) were either neat or modified by hydroxyl or carboxyl groups. Morphology was also characterized by scanning electron microscopy (SEM). The cure kinetics of (H)NBR and modified multiwalled carbon nanotubes ((m‐)MWCNT/(H)NBR) nanocomposites was studied. It was found that the apparent curing and over‐cure activation energies (EA and EA,1) increased with the increasing amount of (m‐)MWCNT. There was a less obvious change in the apparent orders of curing reactions. The results of n‐th order and autocatalytic kinetic model showed that any studied content of (m‐)MWCNT could increase effective thermal conductivity, but decreased the vulcanization rate of (m‐)MWCNT/(H)NBR nanocomposites. Finally, the effect of (m‐)MWCNT content and functionalization on tensile mechanical properties was presented. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers

Application of strain–time correspondence as a tool for structural analysis of acrylonitrile–butadiene copolymer nanocomposites with various organoclay loadings

Acrylonitrile–butadiene copolymer (NBR) nanocomposites were prepared with varied silicate loadings by the melt mixing between NBR and organoclays (OCs) containing intercalants with different polarity and chain length. WXRD exhibited that the NBR nanocomposites had an intercalated structure with distinct differences in gallery height depending on the intercalant characteristics. However, WXRD failed to show a structural change with increasing silicate contents. Hence, tensile strain–stress measurements were carried out at various strain rates (0.162, 0.0975, and 0.0187 s −1), and then the results of tensile measurement applied to the strain–time correspondence (STC) principle, resulting in the tensile modulus master curves of the NBR nanocomposites as a function of time. For pure NBR, a master curve was constructed using only the horizontal shift factor, indicating that the material was structurally homogeneous. However, the NBR nanocomposites required both vertical shift (modulus shift, Γ( α)) and horizontal shift to form the master curves, indicating structural heterogeneity ascribed to the domain structure such as silicate tactoid. From master curves, we found that NBR nanocomposite with OC having polar organic intercalant, NBROC30B, had the lowest n value in the nanocomposites. This indicates that NBROC30B had the most dispersive silicate structure in the nanocomposites due to the polar interaction, being in good agreement with WXRD results. In particular, STC was not applicable at all nanocomposites with silicate loadings over 8 wt%, regardless type of organoclay, and tensile strength and toughness of the nanocomposites with silicate loading of 8 wt% were better than expected. These could be explained as the network-like percolation of the silicate tactoids in all nanocomposites with silicate loadings over 8 wt%, which were consistent with the results observed from HR-TEM.

Dynamic viscoelastic behavior and molecular mobility of acrylonitrile–butadiene copolymer nanocomposites with various organoclay loadings

Layered silicate nanostructures of NBR nanocomposites prepared using the various organoclays (OCs) and silicate loadings were investigated by analyzing the viscoelastic behavior, activation energy ( E a), and average relaxation times ( τ HN) obtained from dynamic mechanical measurements. Viscoelastic behavior revealed that NBR nanocomposite with OC having polar organic modifier (NBROC30B) has the highest elasticity in NBR nanocomposites, indicating the formation of the largest gallery height. In addition, E a and τ HN showed that the mobility of NBROC30B was the closest to that of NBR, providing further evidence that NBROC30B has the largest gallery height. Interestingly, viscoelastic behavior, E a, and τ HN of the nanocomposites with silicate loadings in excess of 7 wt% were remarkably higher than those of the nanocomposites with silicate loadings below 7 wt%. These results imply the sudden change of silicate structure and suggest the formation of three-dimensional network-like percolated silicate structure at NBR nanocomposites with silicate loadings over 8 wt%, which was consistent with HR-TEM results.

Nanocomposites prepared from acrylonitrile–butadiene rubber and organically modifiedmontmorillonite with vinyl groups

Nanocomposites were prepared from acrylonitrile–butadiene rubber (NBR), vinylgroups containing organically modified montmorillonite and additives, such aszinc oxide, stearic acid, and sulfur. The organically modified montmorillonitesused in these nanocomposites were prepared by ion exchange reactions ofN,N′-dimethylalkyl-(p-vinylbenzyl)-ammonium chlorides (DAVBAs,alkyl = octyl, dodecyl, and octadecyl) with sodium montmorillonite(Na+-MMT). NBR nanocomposites were obtained by controlling both the mixing and vulcanizationconditions, by using a Brabender mixer and hot-press process. X-ray diffraction (XRD)analysis shows that, depending on the amount of montmorillonite that is added, bothexfoliated and intercalated nanocomposite structures are formed. The NBR/DAVBA-MMTnanocomposites exhibit much higher mechanical properties (e.g., tensile strength, Young’smodulus, 300% modulus, and hardness) as well as gas barrier properties as compared toNBR Na+-MMT or NBR composites generated from modified montmorillonites without vinyl groups.Consistent with the results of XRD, transmission electron microscopy (TEM) reveals thatthe intercalation and exfoliation structures of the nanocomposites coexist and that theDAVBA-MMT layers are well dispersed in NBR.

Mechanical, thermal, and barrier properties of NBR/organosilicate nanocomposites

AbstractNanocomposites of intercalated and exfoliated organosilicates in acrylonitrile butadiene rubber (NBR) were prepared by a solution‐blending method. The dispersion and intergallery spacings of organosilicates in these nanocomposites were examined by transmission electron microscopy and X‐ray diffraction. Dramatic enhancements in the mechanical and thermal properties of NBR are found by incorporating less than ten parts of organosilicate. In particular, the addition of ten parts of organosilicate provided a more than sixfold increase in tensile strength, a twofold increase in M500, and 168% and 39% enhancements in tear strength and elongation at break compared with pure NBR. The degradation temperature for NBR with ten‐parts' loading of organosilicate was 25°C higher than that of pure NBR. In addition, the relative vapor permeability of the NBR nanocomposites for water and methanol were 85% and 42% lower, respectively, than that of pure NBR. Polym. Eng. Sci. 44:2117–2124, 2004. © 2004 Society of Plastics Engineers.