Dow Epoxy, a business unit of The Dow Chemical Company ("Dow"), has announced two new FORTEGRA toughening technologies designed to improve the toughness of epoxy systems for composites, as well as structural adhesives, electrical laminates, castings and coatings.
FORTEGRA tougheners increase the reliability and durability of composite parts by improving resistance to sudden impact and enhancing the load bearing capability of the composite parts.
Julie Mongeluzi, North American Marketing Manager, Dow Epoxy, said the expanded FORTEGRA product line includes carboxyl terminated butadiene-acrylonitrile (CTBN) elastomer-based tougheners and pre-formed novel core shell rubber (CSR)-based tougheners, which complement the existing proprietary Dow block copolymer technology introduced in 2007. She said all FORTEGRA tougheners are designed to help fabricators overcome the inherent brittleness of epoxy resins without sacrificing essential epoxy thermo-mechanical properties.
Mongeluzi said the new tougheners have been designated FORTEGRA 200-Series and FORTEGRA 300-Series tougheners. FORTEGRA 200-Series products are elastomer-modified epoxy functional adducts formed from the reaction of a liquid epoxy resin and a CTBN elastomer. FORTEGRA 300-Series products are stable dispersions of pre-formed novel core shell rubber (CSR) particles in epoxy resins. FORTEGRA 100-Series tougheners, which were introduced in 2007 and are based on proprietary Dow block copolymer technology, remain in Dow's toughener product line.
"With the addition of the FORTEGRA 200-Series and 300-Series, Dow now offers the most comprehensive portfolio of toughening technologies on the market; which provides customers the flexibility of three distinct chemistries to meet their needs without having to make specific equipment or process changes," Mongeluzi said. According to Mongeluzi, the toughening technology behind FORTEGRA products provides fracture resistance and impact strength without the performance tradeoffs inherent with plasticizers and other technologies designed for flexibilization. "By choosing the appropriate FORTEGRA product, it is possible to improve ductility without negatively impacting formulation viscosity or cured properties including glass transition temperature, corrosion resistance or chemical resistance." She also noted that the new tougheners are compatible with a wide range of liquid epoxy resins and can be directly mixed or diluted with a variety of epoxy resins and diluents.
Dr. Rui Xie, Global Technology Leader for Specialty Epoxy Resins, said FORTEGRA 200-Series tougheners have an elastomer content of about 40 percent by weight. When incorporated at an appropriate amount in an epoxy-based system, the CTBN-based products can significantly improve fracture toughness, adhesion properties and fatigue resistance with minimal impact on thermo-mechanical properties, such as glass transition temperature. Xie also said FORTEGRA 200-Series products are excellent candidates to replace CTBN or other CTBN modified epoxy functional adducts to achieve improved fracture toughness and peel strength.
FORTEGRA 300-Series tougheners are produced as master-batches that contain 15 to 33 weight percent of pre-formed CSR; and the CSR particles remain completely dispersed under normal handling, formulating and curing conditions, said Dr. Nikhil Verghese, Global Platform Leader for Industrial Composites. He added that when the products are incorporated at an appropriate rate in an epoxy-based system, they can significantly improve fracture toughness, fatigue and durability with minimal impact on thermo-mechanical properties at cured resin and composite levels. According to Verghese, the 300-Series products can provide improved fracture toughness while minimizing adverse effects such as viscosity increase that is often encountered in the use of CTBN-based products.
Mongeluzi concluded: "We are very excited by the potential for these new FORTEGRA products. They build on the strength of our existing toughener product line and expand the toughening options of formulators across a broad range of applications."
Samples of FORTEGRA epoxy tougheners are now available for formulator evaluation by contacting a Dow technical representative.