“The increased demand on composite parts is making people look more closely at epoxies now as candidates, whereas in the past cost was such a big factor,” says Mishra. “As more people pay attention to epoxies as an option for higher performance properties, they are coming up with creative ways to use them.” For example, Mishra says in the past anhydride curing agents were not utilized for many infusion applications because the curing temperature wasn’t conducive to infusion processes. That has changed.
“Composites are increasingly replacing metal, so the epoxy industry has been advancing technology on the temperature performance of resins to meet strict service temperature requirements,” says Guillaume. Olin developed a high functionality novalac molecule called D.E.N.™ 440, which enables high Tg after cure without sacrificing ease of processing. “Another major theme is toughening the damage tolerance and fatigue resistance of composite structures to improve their long-term reliability,” says Guillaume.
Of course, cost is nearly always a factor in material selection. “Epoxies tend to be more expensive than standard polyester resins, but in most cases they bridge the gap between specialty high-temperature resistant resins and polyesters,” says Guillaume.
Watkins adds that even if costs are higher pound-for-pound, epoxies may still be cost-competitive. “Sometimes since you have higher strength with an epoxy, you may be able to make a lighter part with less material than a polyester,” he says. “So although the material cost is higher, you are using less and that can offset some of the cost differential.”
Like most other areas in the composites industries, the key to epoxies is educating customers and end users. “People often have pre-conceived notions of what an epoxy does and doesn’t do. We have to explain to potential partners that everything hinges on the particular resin, the particular curing agent and how they are combined,” says Mishra. “So re-educating people about epoxy resin systems is so important. Epoxies are a much broader class of resins than most people realize.”
Want to help grow the market for epoxies and other high-performance materials? Join ACMA’s High Performance Council (HPC). The council works to promote the benefits of high-performance composites in demanding applications to Congress, federal agencies, engineering students and end users. Members of the HPC also promote awareness and use of composites at conferences for various industries. For more information about joining, fill out an interest form at https://tinyurl.com/y88vbuoj.