Sub‐Melt Consolidation of Aerospace‐Grade Thermoplastic Composites for High‐Rate Processing

Abstract

Abstract The processing of thermoplastic composites is often limited by high energy demands and slow cycle times. Out‐of‐autoclave amorphous/crystalline thermoplastic materials for energy‐efficient aerospace‐grade laminates (OATMEAL) addresses these challenges through a unique prepreg architecture. OATMEAL consists of slow‐cooled carbon fiber‐reinforced semicrystalline polyetheretherketone (PEEK) tape sheathed in thin amorphous polyetherimide (PEI) layers. The PEI sheaths are miscible with PEEK and enable interfacial healing below the melting point of PEEK—preserving pre‐existing crystallinity and reducing processing temperatures by 80 °C. The sheaths are thinned via high‐frequency laser ablation down to the PEEK–PEI blending regions, thereby reducing residual stresses and promoting chemical resistance. Fast‐cooled vacuum‐bag‐only oven processing of OATMEAL laminates yields aerospace‐quality parts while enabling processing speeds more than five times faster and reducing energy use by roughly 75% compared with conventional methods. These results represent a significant advancement and a step toward truly high‐rate, large‐scale aerostructure manufacturing.