Preparation and Mechanical Properties Study of High‐Performance <scp>T700</scp> / <scp>PMMA</scp> Composites Based on In Situ Polymerization and Hot‐Pressing Comolding Process

ABSTRACT To address the issues of uncontrollable fiber volume content and insufficient mechanical properties in vacuum infusion molding for preparing polymethyl methacrylate (PMMA) composites, this study proposes the use of an in situ polymerization combined with hot‐pressing cocuring process to fabricate high‐performance T700/PMMA composites. By adding PMMA particles to MMA monomers to regulate the viscosity and polymerization activity of the resin system, the optimal mass ratio was determined to be 100:8, with suitable resin viscosity (100–300 mPa s) and the highest polymerization rate. Subsequently, the pultrusion process parameters for prepreg were systematically optimized. Under the conditions of a pulling speed of 0.2 m/min, temperature of 80°C, and tension of 7 N, high‐quality prepreg was obtained with a resin content of 34.8%, width of approximately 9 mm, and tensile strength reaching 2778 MPa. Finally, the hot‐pressing process for laminates was optimized. By maintaining a temperature of 220°C and pressure of 2 MPa for 20 min, the resulting unidirectional laminate achieved a tensile strength of 1149 MPa and an interlaminar shear strength of 54.72 MPa. This study achieved the controllable preparation of T700/PMMA composite structural properties through comprehensive process optimization, including resin formulation design, prepreg forming, and laminate curing. It provides a complete process solution and experimental basis for the development of high‐performance thermoplastic composites.