Effect of ionic liquids and surfactants on zinc oxide nanoparticle activity in crosslinking of acrylonitrile butadiene elastomer

The goal of this work was to study the influence of several ionic liquids and cationic surfactants on zinc oxide nanoparticle activity in sulfur vulcanization of acrylonitrile butadiene elastomer (NBR). In this article, we discuss the effect of ionic liquids and surfactants on the cure characteristics, crosslink density, and distribution in the elastomer network as well as on mechanical properties of the acrylonitrile butadiene rubber. Ionic liquids (alkylimidazolium salts) and cationic surfactants (alkylammonium bromides) decrease the vulcanization time of rubber compounds. Their application results in the increase of vulcanizate crosslink density as well as of the heterogeneity of elastomer network. The influence of ionic liquids on the acrylonitrile butadiene elastomer properties depends on the anion present in the molecule and on the length of alkyl chains attached to the imidazolium ring. The most active ionic liquids seem to be the ones with the 1‐butyl‐3‐methylimidazolium cation or the BF₄^‐ anion. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Studies on conductivity of acrylonitrile‐butadiene rubber/LiClO4 composite and its modification by adding epoxy resin

Solid polymer electrolytes based on acrylonitrile‐butadiene rubber (NBR) and LiClO₄ were prepared and their conductivity was evaluated. The effect of nitrile group ? CN/LiClO₄ mole ratio on the conductivity was investigated. The maximum conductivity of 1.21 × 10^?4 S cm^?1 (20°C) was achieved in the NBR/LiClO₄ composite at the ? CN/LiClO₄ mole ratio of 1/2.5, which was in accordance with the strongest coordination between ? CN and Li⁺ indicated by Fourier transform infrared spectrometry measurement. The conductivity was further increased by two to three times when 30 phr epoxy resin was introduced into NBR, and the conductivity could retain around the maximum value with the ? CN/LiClO₄ mole ratio ranged from 1/2.5 to 1/3.5, while the conductivity of NBR/LiClO₄ composite existed a decrease in the same range. Field emission scanning electron microscopy and atomic force microscopy characterization showed that epoxy resin significantly improved the dispersion of LiClO₄, leading to better surface smoothness of NBR/epoxy resin/LiClO₄ composite film and contributing to the increase of ionic conductivity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Hydrogenation of Low Molecular Weight Polymers in Ionic Liquids and the Effects of Added Salt

The biphasic hydrogenations of a number of polymeric materials, polybutadiene (PBD), nitrile‐butadiene rubber (NBR) and styrene‐butadiene rubber (SBR), were investigated in a toluene/N,N′‐butylmethylimidazolium tetrafluoroborate, (BMI⁺BF₄⁻) system with a water‐soluble analogue of Wilkinson's catalyst, RhCl(TPPTS)₃ (TPPTS=triphenylphosphine, trisulfonated) at 100 °C and 3.1 MPa. The catalyst shows reasonable activity within ionic liquids with PBD although it was necessary in the case of NBR and SBR to add water as a co‐solvent to solubilize the catalyst within the ionic media. Both the extent of hydrogenation and the ratio of the internal 1,4‐olefins to vinyl 1,2‐olefins were monitored. A clear preference for the external olefins was observed even within NBR and SBR where functionalization on the polymer might enhance the degree of hydrogenation of the internal olefins. The effect of adding NaCl to the PBD system was also investigated. The addition of salt decreases the activity of the catalyst but has no effect on the preference for the hydrogenation of vinyl olefins.     

Synthesis of borate ester‐grafted carboxylated acrylonitrile butadiene rubber and its use as electron acceptor to dissolve lithium perchlorate

A novel borate ester (BE)‐grafted carboxylated acrylonitrile butadiene rubber (XNBR) was synthesized. From Fourier transform infrared, ¹H NMR and elemental analyses, the borate ester was successfully grafted to XNBR, resulting in a more flexible XNBR chain as revealed by differential scanning calorimetry. The binding energies of boron, oxygen, lithium and chlorine atoms of XNBR‐g‐BE–LiClO₄ are quite different from those of XNBR or LiClO₄. Meanwhile, the wavenumbers of C? O? B? O? C, C?O and C? H vibrations of the benzene ring shift towards lower values and a new shoulder peak for ? CN at about 2260 cm^?1 emerges. By integrating fitting peak areas of ? CN groups and ClO₄^?, the fractions of ? CN group and ClO₄^? bidentate bonding in XNBR‐g‐BE–LiClO₄ are much higher than in NBR–LiClO₄. Based on these experiments, a possible dissociation mechanism is proposed in which the boron atom of XNBR‐g‐BE receives electron pairs from ClO₄^?, releasing partial positive charge of Li⁺ to bind with ? CN group. © 2016 Society of Chemical Industry     

Fourier transform near‐infrared and electron spin resonance studies on the crosslinking reaction of liquid carboxylated poly(acrylonitrile‐co‐butadiene) rubber with dicumyl peroxide in dioxane

The crosslinking reaction of liquid carboxylated poly(acrylonitrile‐co‐butadiene) [or nitrile rubber (NBR); acrylonitrile = 10 wt %] with dicumyl peroxide (DCPO) was studied in dioxane by means of Fourier transform near‐infrared spectroscopy (FT‐NIR) and electron spin resonance spectroscopy (ESR). Among the three butadiene units (1,2, cis‐1,4, and trans‐1,4 units) of NBR, only the pendant vinyl group of the 1,2 unit showed an absorption at 6110 cm^?1 from the FT‐NIR examination of dioxane solutions of NBR, 1‐octene, 3,3‐dimethyl‐1‐butene, trans‐2‐octene, cis‐5‐octen‐1‐ol, poly‐cis‐1,4‐butadiene, and poly‐1,2‐butadiene. The crosslinking reaction was followed in situ in dioxane by the monitoring of the disappearance of the pendant vinyl double bond with FT‐NIR. The initial disappearance rate (R₀) of the vinyl group was expressed by R₀ = k[DCPO]^0.9[NBR]^?0.2 (120°C). The overall activation energy of the reaction was calculated to be 20.7 kcal/mol. This unusual rate equation suggests unimolecular termination due to degradative chain transfer and depressed reactivity of the vinyl group caused by crosslinking. ESR study of the reaction mixture revealed that an allyl‐type polymer radical was formed in the reaction, and its concentration increased with time and was then saturated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2095–2101, 2003     

The grafting reaction of epoxycyclohexyl polyhedral oligomeric silsesquioxanes with carboxylic methoxypolyethylene glycols and the properties of composite solid polymer electrolytes with the graftomer

A novel organic–inorganic hybrid of epoxycyclohexyl polyhedral oligomeric silsesquioxane (e‐POSS)–grafted carboxylic methoxypolyethylene glycols (mPEG‐COOH), that is, a POSS‐mPEG graftomer, was synthesized. The grafting reaction of e‐POSS and mPEG‐COOH was characterized by Fourier transform infrared (FTIR) and ¹H‐NMR spectroscopy. Then the graftomer was used to develop new composite solid polymer electrolyte (SPE) films with a carboxylated nitrile rubber–epoxidized natural rubber (XNBR‐ENR) self‐crosslinked blend system as a dual‐phase polymer matrix. The self‐crosslinked reaction of the XNBR‐ENR matrix was investigated using ATR‐FTIR. The morphology of the SPE films and the distribution of lithium salt were investigated using field emission scanning electron microscopy and X‐ray diffraction, and the result illustrated that the addition of POSS‐mPEG could promote and accelerate the dissociation of LiClO₄. The best effect within the range of this study was achieved when 25 phr POSS‐mPEG was involved. The differential scanning calorimetry analysis proved that the glass‐transition temperature of the composite SPE films was reduced with the increase of POSS‐mPEG. The ionic conductivity of the composite SPE films was investigated by electrochemical impedance spectroscopy. The highest ionic conductivity in this study of 2.57 × 10^?5 S cm^?1 was obtained with 25 phr POSS‐mPEG loading. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44460.     

Antistatic effects and mechanism of ionic liquids for methyl vinyl silicone rubber

The effect of two ionic liquids (ILs), namely, 1‐allyl‐3‐methyl imidazolium chloride ([AMIM]Cl) and 1‐ethyl‐3‐methyl imidazolium tetrafluoroborate ([EMIM]BF₄), on the surface and volume resistivities, mechanical properties, transparency, and water contact angle of methyl vinyl silicone rubber (MVQ) were investigated. The chemical structures of the two ILs before and after heat treatment were characterized by Fourier transform infrared spectroscopy. The morphology and fluorine and chlorine elemental dispersion were characterized by field emission scanning electron microscopy and energy‐dispersive X‐ray spectroscopy mapping, respectively. The antistatic mechanism was revealed. The results show that the MVQ–[EMIM]BF₄ composites had lower surface and volume resistivities than the MVQ–[AMIM]Cl composites. The mechanical properties of the MVQ–[EMIM]BF₄ and MVQ–[AMIM]Cl composites were slightly lower than those of the pristine MVQ. With increasing [EMIM]BF₄ content, the surface and volume resistivities and water contact angle of the MVQ–[EMIM]BF₄ composites decreased. When the content of [EMIM]BF₄ was 2.0 phr, the MVQ–[EMIM]BF₄ composites showed better antistatic performance with lower surface and volume resistivities of 9.6 × 10⁹ Ω and 1.2 × 10¹¹ Ω cm, respectively. The antistatic mechanism of the MVQ–IL composites was ascribed to the synergistic effect of ionic migration and moisture absorption. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45180.     

Ionic elastomer blends of zinc salts of maleated natural rubber and carboxylated nitrile rubber: Effect of grafted maleic anhydride

Zinc neutralized maleated natural rubbers (Zn‐MNR) were prepared by solution grafting and neutralization with zinc acetate in one‐step. It was later used for blending with carboxylated nitrile rubber (XNBR) in the composition of 50/50 parts by weight. The effect of grafted anhydride content (1.2, 1.6, 2.0, and 2.5% wt of NR) on the tensile properties of ionic rubber blends (Zn‐MNR/XNBR) was investigated. The tensile strength of the ionic blends was found to be greater than those of pure rubbers. The modulus, tensile, and tear strength of the blends dramatically increased with increasing levels of grafted anhydride. The ionic rubber blends also possessed superior physical properties compared to those of the corresponding nonionic rubber blends (MNR/XNBR). Dynamic mechanical thermal analysis and scanning electron microscopic studies were performed to verify the process of mixing. Fourier transform infrared spectroscopic studies were carried out to characterize the nature of specific intermolecular interactions between Zn‐MNR and XNBR chain segments. The results indicated that the ion‐ion (Zn⁺ ‐COO^?) interactions between Zn‐MNR and XNBR are formed at the interface, which provides the mean of compatibilization in the ionic rubber blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

ZnBr2‐catalyzed chemical effects in poly(acrylonitrile‐ co‐butadiene)

The excellent chemical properties and resistance to oil of poly(acrylonitrile‐co‐butadiene), or nitrile–butadiene rubber (NBR), has led to the extensive use of these elastomers as O‐ring material in the oil extraction industry. The degradation of NBR gaskets is known to occur during the well completion and oil extraction process when they are exposed to bromide fluids such as ZnBr₂‐based completion fluid. Samples of NBR, polyacrylonitrile, and polybutadiene were exposed to ZnBr₂‐based completion fluid and analyzed by attenuated total reflectance (ATR) and diffuse reflectance IR. These analyses showed that the ZnBr₂ completion fluid promoted the hydrolysis of the nitrile group to form amides and carboxylic groups. The carbon–carbon double bonds in NBR were unaffected after short exposure to ZnBr₂‐based completion fluid but were quickly hydrated in acidic bromide mixtures. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1250–1257, 2003     

Enhanced electrical conductivity of polyindole prepared by electrochemical polymerization of indole in ionic liquids

The in situ electrical conductivity (resistance) of electrochemically prepared polyindole (PIn) in ionic liquids was found to be strongly dependent on the nature of the solvents, size of ionic liquid counter ions and preparation technique. Accordingly, the conductivity can be enhanced by about one order of magnitude when using a 1‐butyl‐3‐methylimidazolium tetrafluoroborate [BMIm] [BF₄^‐] or 1‐butyl‐3‐methylimidazolium hexafluorophosphate [BMIm] [PF₆^?] in comparison to acetonitrile (ACN). Moreover, the growth of polyindole in ionic liquid on gold electrode surface is faster than growth of polymer in acetonitrile. Additionally, a significant enhancement of the conductivity by using ionic liquids during the polymerization could be achieved. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40094.     

Fabrication and characterization of NBR/MWCNT composites by latex technology

To develop a rubber composite with excellent electrical properties, a sort of synthetic rubber, acrylonitrile butadiene rubber (NBR) with CN dipoles as matrix, multi‐walled carbon nanotubes (MWCNTs) as filler, was synthesized. NBR composites reinforced with 0.5, 1.5, 3, 10, and 20 phr MWCNT contents were fabricated by latex technology. The electrical conductivity, dielectric characteristics, and electromagnetic interference (EMI) shielding effectiveness at room temperature of NBR/MWCNT composites were investigated. MWCNTs were found well dispersed into NBR matrix even for 20 phr content by FESEM observation. The electrical conductivity increased with an increment of MWCNT content. The dielectric constant was over 10⁴ at 10³ Hz frequency for 10 and 20 phr MWCNTs‐reinforced NBR composites. It was attributed to the increased electrons and interface polarization. The improved conductivity and dielectric permittivity resulted in an enhanced EMI shielding effectiveness. The EMI shielding effectiveness reached 26 dB at 16.7 GHz frequency for NBR/20 phr MWCNT composite with 1.0 mm thickness. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Polymer blends of carboxylated butadiene‐acrylonitrile copolymer (nitrile rubber) and polyamide 6 developed in twin screw extrusion

Polymer blends of carboxylated butadiene‐acrylonitrile copolymer (nitrile rubber) and polyamide 6 (PA6) were developed in twin screw extrusion. The rubber was cured with SP 1045 methylol phenolic resin during melt mixing in twin screw. Effect of degree of carboxylation in the rubber phase on blend properties has been assessed. Phase morphologies have been characterized using transmission electron microscopy. A compatibilizing NBR‐g‐Nylon 6 graft copolymer generated in situ during melt mixing via interfacial reaction between the ? COOH groups in NBR and the ? NH₂ end groups in nylon 6 has been effective in generating a fine and stable dispersion of the rubber within the polyamide matrix. The graft copolymer has been characterized by DMTA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 372–377, 2007     

Aromatic sulfur‐nitrogen extraction using ionic liquids: Experiments and predictions using an a priori model

The tie‐line composition of three quaternary system namely 1‐ethyl‐3‐methylimidazolium acetate ([EMIM][OAc]) ([EMIM][OAc]) (1) + thiophene (2) + pyridine (3) + toluene (4), 1‐ethyl‐3‐methylimidazolium ethylsulphate ([EMIM][EtSO₄]) (1) + thiophene (2) + pyridine (3) + toluene (4), 1‐ethyl‐3‐methylimidazolium methylsulphonate ([EMIM][MeSO₃]) (1) + thiophene (2) + pyridine (3) + toluene (4) were experimentally determined at 298.15 K. The measured tie‐line data were successfully correlated with the nonrandom two liquid and UNIversal QUAsiChemical model prediction which gave less than 1% root mean square deviation (RMSD). [EMIM][MeSO₃] looks to be a promising solvent for the simultaneous separation having distribution ratios less than unity for both thiophene and pyridine. The quantum chemical‐based conductor like screening model for real solvent (COSMO‐RS) model was then used to predict the tie‐line composition of quaternary systems. COSMO‐RS gave the RMSD for the studied systems to be 8.41, 8.74, and 6.53% for the ionic liquids, respectively. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4806–4815, 2013     

抗湿滑轮胎胎面胶配方的研究

研究羧基改性溶聚丁苯橡胶(SSBR)、丁腈橡胶(NBR)和高性能橡胶助剂Nanoprene在抗湿滑轮胎胎面胶中的应用。结果表明:在胎面胶配方中,以SSBR等量替代ESBR,胶料的门尼焦烧时间和t90延长,硫化胶的300%定伸应力和撕裂强度增大,湿抓着性提高,压缩生热降低,耐磨性能变化不大;加入20份Nanoprene,胶料的门尼焦烧时间和t90延长,硫化胶的300%定伸应力增大,湿抓着性提高,压缩生热降低,耐磨性能下降;加入5份NBR,胶料的硫化特性、硫化胶的物理性能和压缩生热变化不大,湿抓着性提高,耐磨性能下降。     

Multi-walled carbon nanotube reinforced self-crosslinking hydrogenated carboxylated nitrile butadiene rubber latex film with improved properties

A dielectric self-crosslinking hydrogenated carboxylated nitrile butadiene rubber (HXNBR) latex film was prepared by diimide reduction hydrogenation of XNBR latex and the doping of multi-walled carbon nanotube (MWCNT). The structures of the HXNBR and XNBR were characterised by Fourier transform infrared spectroscopy (FTIR) and ¹HNMR, confirming the successful hydrogenation of XNBR. The mechanical, thermal, and electrical properties of the prepared HXNBR latex films were studied, and the HXNBR latex film reinforced by only 3?phr MWCNTs exhibited improved mechanical, thermal, and dielectric properties.     

Alternative Synthesis of a Dialkylimidazolium Tetrafluoroborate Ionic Liquid Mixture and its Use in Poly(acrylonitrile‐butadiene) Hydrogenation

An alternative synthesis of a dialkylimidazolium ionic liquid mixture is developed in order to produce inexpensive solvents for biphasic hydrogenation of poly(acrylonitrile‐butadiene) rubbers (NBR) catalyzed by RuHCl(CO)(PCy₃)₂.     

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

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

Tailoring the structure of Kevlar nanofiber and its effects on the mechanical property and thermal stability of carboxylated acrylonitrile butadiene rubber

Water-dispersible hydrolyzed Kevlar nanofibers (hANFs) prepared by acid-assisted hydrothermal treatments of Kevlar nanofibers (ANFs) were first incorporated into carboxylated acrylonitrile butadiene rubber (XNBR) by a latex co-coagulation method. The obtained hANFs maintained the one-dimensional nanofibrous morphology and crystal structure as ANFs. There were amounts of polar groups appearing at the end of hANFs molecular chains after hydrothermal process, which led to the strong hydrogen bonding interaction between the filler and XNBR matrix. The results indicated that hANFs had significant reinforcement effects on the mechanical properties, crosslink density, and thermal stability of XNBR matrix. In comparison with those of neat XNBR, the tensile strength, tear strength, crosslink density, and maximum heat decomposition temperature (T_max) of XNBR/hANFs nanocomposites filled with 7 phr hANFs increased by 236%, 161%, 35%, and 19.64 °C, respectively. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47698.     

Catalytic hydrogenation of nitrile rubber using palladium and ruthenium complexes

The catalytic hydrogenation of acrylonitrile‐butadiene copolymer (nitrile rubber, NBR) using Pd(OAc)₂ or RuCl₂(PPh₃)₃ catalysts has been investigated in order to produce a totally saturated nitrile rubber. The hydrogenation of NBR is effective with both catalysts and achieved total conversion under the appropriate reaction conditions. In the case of palladium the effects of reaction parameters such as reaction temperature, pressure, time, catalyst concentration, and NBR concentration have been investigated. Even though both ruthenium‐ and palladium‐based catalysts are effective in the production of HNBR, the former requires harsh reaction conditions and has the drawback of gel formation under high conversion, motivating the migration to RuCl₂ (PPh₃)₃ as an alternative catalyst. The degree of hydrogenation was determined by IR and NMR spectroscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Stabilization of native penicillin G acylase by ionic liquids

Five different ionic liquids, based on dialkylimidazolium cations associated with perfluorinated and bis{(trifluoromethyl)sulfonyl}imide anions, were used to investigate the scope and limitations of these new solvents as media for penicillin G acylase‐catalyzed reactions. Deactivation of the native enzyme in ionic liquids (ILs) and in organic solvents (toluene, dichloromethane and 2‐propanol) at low water content and 40 °C was investigated using the hydrolysis of penicillin G as activity test. Native penicillin G acylase shows greater stability in IL media than in organic solvents. For example, a half‐life time of 23 h was obtained in 1‐ethyl‐3‐methylimidazolium bis{(trifluoromethyl)sulfonyl}imide, [emim⁺][Tf₂N^?], which was about 2000‐fold higher than that in 2‐propanol. An enhancement of the PGA stability was observed by the presence of substrate in ionic liquids based on tetrafluoroborate and hexafluorophosphate anions, achieving the highest increase of the half‐life time in 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([bmim⁺][PF₆^?]), which was about 9‐fold higher than the half‐life time in the absence of substrate. Copyright © 2007 Society of Chemical Industry