Epoxy-terminated polybutadiene-toughened

To a lesser extent, amine-terminated polybutadiene/acrylo-nitrile (ATBN) liquids are also used by epoxy formulators. This polymeric disecondary amine is employed in admixture with amines, amldoamlnes or fatty polyamides of choice (10, 11). Thus, one admixes chemical and polymeric amines to create a novel toughening or flexibilizing hardener package. 

Elastomer-modified epoxy resins are used in composites and structural adhesives, coatings, and electronic applications. Similar approach to toughen epoxy vinyl esters using other elastomeric materials has been reported (204). Other elastomer-modified epoxies include epoxy-terminated urethane prepolymers, epoxy-terminated polysulfide, epoxy-acrylated urethane, and epoxidized polybutadiene. Preformed dispersions of epoxy-insoluble elastomers have been developed and reported to achieve toughening without Tg reduction (205,206). 

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). 

Low molecular weight polybutadiene and butadiene-acrylonitrile copolymers terminated with carboxyl, vinyl, amine, epoxy, phenol, and hydroxyl groups have been widely used as toughening agents both for epoxy and polyester resins. Thermally reactive isoprene-acrylonitrile and ethylacrylate-butylacrylate copolymers have also been used [82,83]. 

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