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

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.