Liquid carboxyl terminated butadiene-acrylonitrile

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... [Pg.546]

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). [Pg.133]

Toughening epoxy matrices using liquid reactive rubbers (such as carboxyl-terminated butadiene acrylonitrile, CTBN, or the amine-terminated equivalent, ATBN) has been widely reported in the literature. Spherical rubber particles of a proper size distribution (usually 1-5 pm) can effectively enhance the toughness through crack blunting or cavitation mechanisms. However, rubber modification of epoxies becomes... [Pg.400]

In order to improve the internal stress performance even further or to provide toughness for potting and adhesive applications it is advantageous to introduce reactive additives to the basic epoxide compound formulation. One of the most popular additives that has found considerable use in this type of application is a rubber-like liquid copolymer known as carboxyl terminated butadiene/acrylonitrile (CTBN). The generalised molecular structure of this material is ... [Pg.321]

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 ... [Pg.744]

Elastomeric modifiers are used to increase the peel strength (toughness) of epoxy resin adhesives. The most commonly used elastomeric materials are functionally terminated polybutadiene resins made by the B.F. Goodrich Company, Chemical Group under the trade name of Hycar Reactive Liquid Polymers. Initially, carboxyl-terminated butadiene acrylonitrile (CTBN) resins were introduced the carboxyl terminated materials are usually adducted with the epoxy resin to improve compatibility and to increase the toughness. [Pg.355]

High molar mass epoxy prepolymers containing rabber dispersions based on carboxyl-terminated butadiene-acrylonitrile copolymer were prepared from initially miscible solution of low molar mass epoxy prepolymers, bisphenol A and carboxyl-terminated NBR. During chain extension inside a twin screw extruder due to epoxy-phenoxy and epoxy-carboxy reactions, a phase separation process occurs. Epoxy-phenoxy and epoxy-carboxy reactions were catalysed by triphenylphosphine. The effect of reaction parameters (temperature, catalyst, reactant stoichiometry) on the reactive extrasion process were analysed. The structure of the prepolymers showed low branching reactions (2-5%). Low molar mass prepolymers had a Newtonian rheological behaviour. Cloud-point temperatures of different reactive liquid butadiene aciylonitrile random copolymer/epoxy resin blends were measured for different rubber concentrations. Rubber... [Pg.100]

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. [Pg.334]

Materials. Hycar CTBN is a registered trade name of a carboxyl-terminated, liquid copolymer of butadiene and acrylonitrile (B. F. Goodrich Chemical Co.). For most purposes it can be represented structurally as ... [Pg.330]

Liquid carboxy1-terminated butad iene-acrylonitrile copolymer was prepared in this laboratory (5). The number average molecular weight was 2500 and acrylonitrile content 30 wt %. The butadiene unit was mainly in 1,4-trans structure with 11% 1,2-structure. The carboxyl functionality was about 1.9. This product was designated as E-30. [Pg.656]