Acrylonitrile-butadiene rubber carboxylated

Zinc peroxide is used as the curative for carboxylated acrylonitrile-butadiene rubber (XNBR) compounds. It confers better scorch safety than does zinc oxide. It is usually added in a masterbatch form. 

Vlassopoulos et al. (1998) examined the gelation of three epoxy-rubber thermoset blends (based on TGDDM/DDS/(acrylonitrile/butadiene rubber/methacrylic acid copolymer) of the same chemistry but different pre-cure treatments. The pre-treatments used heat and catalysts to promote epoxy-carboxyl reactions, and there was some evidence of a decrease in gelation time and an effect on pre-gel rheology with these treatments. 

Additives. Acrylonitrile-butadiene rubbers were provided by BFGood-rich (Brecksville, OH). The amino-terminated butadiene-acrylonitrile (ATBN) rubber was obtained by reacting carboxyl-terminated butadiene-acrylonitrile (CTBN) with an excess diamine, Unilink 4200 (from UOP, El Dorado Hills, CA) consequently, free diamine molecules always remained in the rubber. The rubbers have almost the same molar mass but different end groups, which have been characterized in a previous work (20). Their structures are given in Chart I, and they are described in Table I. The two poly(ether sulfone)s (PESs) (Victrex, from ICI, United Kingdom) used in this study are described in Table II. 

Styrene-butadiene rubber latex (SBR, GRS) and acrylonitrile-butadiene rubber latex (NBR) are two of the earliest to arrive on the market. Since then, many other types have appeared, with poly(vinyl acetate) and copolymers, acrylics (generally polymers and copolymers of the esters of acrylic acid and methacrylic acids), and carboxylic-SBR types being the major products. Since latices are aqueous emulsions, less... 

Fig. 35. Dependence of fracture energy on the modifier composition (CTBN 1300 X 9 = carboxyl-tenninated acrylonitrile, acrylic acid and butadiene rubber with 18% acrylonitrile and 2% acrylic acid contents CTBN 1300x 13 = carboxyl-terminated acrylonitrile, butadiene rubber with 26% acrylonitrile content) (Reprinted from Journal of Materials Science, 27, T.K. Chen, Y.H. Jan, Fracture mechanism of toughened epoxy resin with bimodal rubber-particle size distribution, 111-121, Copyright (1992), with kind permission from Chapman Hall, London, UK)...

Most of the earlier efforts have been paid in changing the surface character of clay minerals. Albeit the modified clay minerals are fairly compatible with the polar rubber like acrylonitrile butadiene rubber (NBR), carboxylated nitrile rubber (XNBR), chloroprene rubber (CR), etc., its dispersion in nonpolar rubbers like NR, styrene butadiene rubber (SBR), ethylene propylene diene rubber (EPDM), butadiene rubber (BR), etc. is rather unsatisfactory. Figure 8.3(a) and (b) display the state of dispersion of organomodified... 

The best approach has been to react (Step polymerization) the resoles, during cure, with suitable high-molecular weight polymers such as polyvinyl acetals, epoxies, acrylonitrile butadiene rubbers (NBR) or, better, their carboxylated variants, polyurethanes and polyamides. The methylol groups on the phenolic react with the active hydrogen groups (hydroxyls or secondary amines) on the polymer. 

A. Laskowska, M. Zaborski, G. Boiteux, O. Gain, A. Marzec, W. Maniukiewicz, Effects of unmodified layered double hydroxides MgAl-LDHs with various structures on the properties of filled carboxylated acrylonitrile-butadiene rubber XNBR, European Polymer Journal, ISSN 0014-3057 60 (November 2014) 172-185. http //dx.doi.0rg/lO.lOl6/j. eurpolymj. 2014.09.013. 

The natural rubber does not generally exhibit all the desired properties for use in the rubber industry. Thus, it is possible to obtain better mechanical and physical properties at a lower cost by blending natural rubber with synthetic rubbers. Normally, natural rubber is deteriorated by ozone and thermal attacks due to its highly unsaturated backbone, and it also shows low oil and chemical resistances due to its non-polarity. However, these properties can be achieved by blending it with low unsaturated ethylene propylene diene monomer rubber, styrene butadiene rubber, carboxylate styrene butadiene rubber, nitrile butadiene rubber, chloroprene rubber, chlorosulfonated polyethylene rubber, and acrylonitrile butadiene rubber. 

Wu, Y.-P., et al. Structure of carboxylated acrylonitrile-butadiene rubber (CNBR)-clay nanocomposites by co-coagulating mbber latex and clay aqueous suspension. Journal of Applied Polymer Science, 2001. 82(11) 2842-2848. 

Other polymers used in the PSA industry include synthetic polyisoprenes and polybutadienes, styrene-butadiene rubbers, butadiene-acrylonitrile rubbers, polychloroprenes, and some polyisobutylenes. With the exception of pure polyisobutylenes, these polymer backbones retain some unsaturation, which makes them susceptible to oxidation and UV degradation. The rubbers require compounding with tackifiers and, if desired, plasticizers or oils to make them tacky. To improve performance and to make them more processible, diene-based polymers are typically compounded with additional stabilizers, chemical crosslinkers, and solvents for coating. Emulsion polymerized styrene butadiene rubbers (SBRs) are a common basis for PSA formulation [121]. The tackified SBR PSAs show improved cohesive strength as the Mooney viscosity and percent bound styrene in the rubber increases. The peel performance typically is best with 24—40% bound styrene in the rubber. To increase adhesion to polar surfaces, carboxylated SBRs have been used for PSA formulation. Blends of SBR and natural rubber are commonly used to improve long-term stability of the adhesives. 

The elastomeric materials most commonly used for this purpose are carboxyl-terminated acrylonitrile-butadiene copolymers. The carboxyl groups react with the epoxy group to produce an epoxy-terminated rubber that promotes interfacial bonding in two-phase systems (9). By controlling the concentrations of M, Xj, X2, Z, and U, a broad range of compatibilities can be achieved. Impact resistance and fracture toughness are Increased with minimal sacrifice in molulus and elevated-temperature performance. 

The second ABCP-type materials of commerce are the rubber-toughened epoxy resinsUsually the epoxy resins are based on the diglycidyl ether of bisphenol A (DGEBA). Carboxyl-terminated butadiene-acrylonitrile (CTBN) rubber is the elastomer of preference. A typical composition is ... 

Masaki, K., etal., Fourier-Transform Near-Infrared and Electron-Spin-Resonance Studies on the Cross-Linking Reaction of Liquid Carboxylated Poly(Acrylonitrile-Co-Butadiene) Rubber with Dicumyl Peroxide in Dioxane. J. Appl. Polym. ScL, 2003. 89 2095-2101. 

More recently Crosbie and Philips [85,86] investigated the toughening effect of several reactive liquid rubbers (carboxyl terminated butadiene-acrylonitrile, vinyl terminated butadiene-acrylonitrile, hydroxyl terminated polyether, polyepichlorohydrin) and an unspecified experimental reactive liquid rubber developed by Scott Bader Ltd. on two different polyester resins a flexibilized isophthalic-neopentyl glycol polyester resin, PVC compatible and an epoxy modified polyester resin, which is preaccelerated. The results of these studies are summarized as follows ... 

Low molecular weight liquid nitrile rubbers with vinyl, carboxyl or mercaptan reactive end groups have been used with acrylic adhesives, epoxide resins and polyesters. Japanese workers have produced interesting butadiene-acrylonitrile alternating copolymers using Ziegler-Natta-type catalysts that are capable of some degree of ciystallisation. 

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