JD Lincoln (Costa Mesa, Calif.) has launched L-316/11, a new epoxy surface improvement film developed specifically for use with composite parts molded by low-pressure vacuum bag processing. The film is said to be particularly useful in the production of one-shot honeycomb-cored sandwich structures where telegraphing of the honeycomb structure is a risk factor. The film, formulated to cocure with most epoxy systems, requires a 250°F/121°C cure cycle, but reportedly can tolerate cycling at 350°F/177°C and is compatible with out-of-autoclave prepreg systems. It can be applied as a surface layer to fiberglass, aramid or carbon fiber-based laminates where it reportedly provides a tough, readily sandable, paint-ready finish. The film is flame retardant and is capable of meeting the requirements of Federal Aviation Requirement (FAR) Part 25.853 (vertical burn). It comes standard on a polyester veil with a total areal weight of 0.035 lb/ft² (171 g/m²), but it also can be supplied in an unsupported format.
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