Carboxyl terminated butadiene

Carboxylic functional polyester curing agents, 10 401-406 Carboxyl ion system, 19 193 Carboxyl-terminated butadiene nitrile, rubbers and, 10 376-375 Carboxymethyl cellulose (CMC),... 

CTBN type elastomers (carboxyl-terminated butadiene acrylonitrile) used to toughen this epoxy system. The Tg peak of the elastomer (-30°Q was shifted to higher temperatures suggesting that electron interaction resulted in crosslinking. The fact that the Tg peak disappeared at 10 rads suggests that crosslinking in the elastomer was extensive at high dose levels. 

CTBN Carboxyl-Terminated Butadiene Acrylonitrile Rubber... 

Piperidine and carboxyl terminated butadiene acrylonitrile copolymer (CTBN) at 75 °C. 

CTBN carboxyl-terminated butadiene-acrylonitrile rubber DETA diethylenetriamine... 

Rubber was a carboxyl-terminated butadiene-acrylonitrile copolymer. Mean diameter of rubber particles =1.6 pm. Rubber concentration was 15 phr, giving volume fraction of 0.18 4 Containing vf (glass) = 0.1 rubber = 15 phr... 

It is obvious from these data that CTBN (the carboxyl terminated butadiene-acrylonitrile copolymer) is the most effective modifier, and therefore it was selected for further study. As the concentration of the elastomer was increased to levels up to 100 parts, the impact also increased. The data in Table II show that the room temperature impact of ERL-4221 increased from 40 inch-lbs to greater than 320 inch-lbs by adding 100 phr or 33 wt % of CTBN. At very low temperatures ( —160°F) the impact of the system modified with 60 parts, or 23 wt %, of CTBN was 120 inch-lbs. These impact improvements appear to be directly proportional to the concentration of the elastomer modifier. 

The carboxyl terminated butadiene-acrylonitrile rubber, which is soluble initially in the liquid phase, precipitates out as a second phase during the crosslinking reaction of the epoxy. The cured specimens are... 

Carboxyl-terminated butadiene-acrylonitrile copolymer, mentioned above, was found to have 4-cyanopentanoic acid end-group originating from 4,4,7-azobis(4-cyanopentanoic acid) initiator [32],... 

Epoxy-nitrile Nitrile-epoxy adhesives are composed of solid epoxy resin modified with carboxyl-terminated butadiene nitrile (CTBN) copolymer. The CBTN is introduced into die epoxy resin at elevated temperatures. The modification provides toughness and high peel strength without sacrificing heat and chemical resistance. The film adhesives are widely used in the aerospace industry in the construction of jetliners. 

The epoxy-nitrile adhesives were introduced commercially in the late 1960s. They consisted primarily of DGEBA epoxy resin modified with carboxyl-terminated butadiene nitrile (CTBN) rubber. These first nitrile copolymers were available from B.F. Goodrich under the trade name of Hycar. The most convenient form of epoxy nitrile adhesive, especially when one is bonding large parts (aircraft structures), is a supported film. However, solvent solutions of epoxy-nitrile adhesives have also been commercially available. 

Functionalized, liquid polybutadiene derivatives have also been developed as hybrid flexiblizers for epoxy resins. Carboxyl-terminated butadiene/acrylonitrile polymers, butadiene homopolymers, and maleic anhydride-amino acid grafted butadiene homopolymers have been used as flexibilizers to impart good low-temperature strength and water resistance to DGEBA-based epoxy adhesives. An epoxy system toughened by polybutadiene with maleic anhydride is claimed to provide a hydrophobic backbone, low viscosity, softness, and high tensile strength and adhesion (Table 7.10). 

FIGURE 8.6 Chemical structure of carboxyl-terminated butadiene acrylonitrile (CTBN). 

Effect of Molecular Structure. Table III shows the effects of the molecular structure of the liquid polymer on the fracture energy of toughened systems. The CTIN is a carboxyl terminated isoprene-acrylonitrile copolymer CTBS is a carboxyl terminated butadiene and styrene copolymer, and CTA is a copolymer of ethyl acrylate-butyl acrylate. 

Fig. 13. TXT cure diagram temperature of cure vs. the times to phase separation (doud point), gelation and vitrification for a neat and two rubber-modified systems. of the neat system is also included. The systems studied were DER331/TMAB O, gelation , vitrificaticm modified with IS parts rubber per hundred parts epoxy 1) pr eacted carboxyl-terminated butadiene-acrylonitrile (CTBN) copolymer containing 17% acrylonitrile (K-293, Spencer Kellog Co.) A, phase separation , gelation , vitrification, and 2) polytetramethylene oxide terminated with anmiatic amine (ODA2000, Polaroid Corp.) A. phase separation O, gelation O, vitrification. (DER331/TMAB/ K-293 data from Ref. )...

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. 

CTBN Carboxyl terminated butadiene acrylonitrile rubber... 

These composites may be flexibllzed by the addition of polyethylene sulfide (Thiokol) or a carboxyl terminated butadiene polymer. Coal tar may also be added as an extender, polyvinyl-p-vlnylphenol may be used as the curing component and hard aggregates may be added to improve wear resistance.12. 

Carboxyl-Terminated Butadiene-Acrylonitrile-Modifl Epoxy Resin and Its Graphite Fiber-Reinforced Composite... 

Fig. 13. Experimental CPC (A) and calculated binodal (broken curve) and spinodal (dotted curve) curves for a binary system composed of a DGEBA-based epoxy monomer (M = 479 gmol ) and a carboxyl-terminated butadiene-acrylonitrile rubber (CTBN) (Reprinted from Polymer, 30, D. Verchere, H. Sautereau, J.P. Pascault, S.M. Mos-chiar, C.C. Riccardi, R.J.J. Williams, Miscibility of epoxy monomers with carboxyl-terminated butadiene-acrylonitrile random copolymers, 107 -115, Copyright (1989), with kind permission from Butterworth-Heinemann journals, Elsevier Science Ltd, The Boulevard, Langford Lane, Kidlington 0X5 1GB, UK)...

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