There’s a new generation of epoxy resin systems tailor-made for an array of applications.
Epoxy matrix systems have been around for more than 75 years, with recent innovations moving away from off-the-shelf products to custom-made solutions. Advancements hinge on teamwork, such as an ongoing collaborative project between Dixie Chemical, which manufactures specialty chemicals, and four other industry partners. Together, they are developing an all-composite wall panel for damage-resistant modular buildings.
“The panel design can be tailored to withstand different levels of energy absorption, including shock waves from nearby explosions,” says Vinay Mishra, Ph.D., business development manager for the thermoset platform at Dixie Chemical. Key to the product is a new anhydride-cured epoxy resin system that is formulated for high strength and high glass transition temperatures (Tg) and uses a proprietary variation of the resin infusion process.
Dixie Chemical has assembled a team of experts to offer input, materials and production on everything from reinforcements to engineering and blast-resistant buildings. Those partners include Engineered Syntactic Systems, Core Composites, Clear Carbon & Components Inc. and Hunter Buildings LLC. The panels are currently undergoing various tests, and the team expects the first ones will be installed in prototype buildings late this year.
For demanding applications such as the wall panels, epoxy resins are often the clear choice. “End users are looking for higher and higher performance,” says Michael Watkins, senior technical advisor for epoxy thermosets at Dixie Chemical. “In the old days, polyesters and vinyl esters worked just fine. Now if people want higher performance, higher strength or higher temperature service, then they are starting to look at epoxies.”
A Proven Record
Epoxy resins have a proven record in a wide range of applications, from coatings and adhesives to composite parts and concrete repair. There are two basic kinds of epoxies: Ambient cure, which cure at room temperature, and heat cure, which require baking to cure. Both kinds can be used in composite applications, however heat cure epoxies are more commonly utilized.
Epoxies are used mainly in fabricating high-performance composites with superior mechanical properties, resistance to corrosive liquids and environments, exceptional electrical properties, good performance at elevated temperatures and good adhesion to a substrate. “The defining feature of epoxies is they are able to cure to a very high degree of cross-linking, which leads to all these superior properties,” says Mishra.
Other benefits of epoxies include their ease of processing and balance of thermo-mechanical properties following cure. They may include low viscosity liquids appropriate for processes like infusion and filament winding or higher viscosity semi-solids used in pre-impregnated composites and laminates, according to Jean Luc Guillaume, global wind and composites marketing director of Olin Corporation, a producer of epoxy materials. “Epoxy resins can deliver high glass transition temperatures after cure to meet the most demanding service requirements,” he says.