Resin transfer molding with powder‐coated preforms

Abstract Incomplete fiber wetting in a resin transfer molded composite may result in poor surface finish, high void content, and reduced mechanical properties. This work studied the use of tows that are precoated with a powdered version of the liquid molding resin (towpregs). The goal is to see if such preforms improve the final part properties because of better fiber wetting. Hercules 12K AS‐4 fibers and PR500 (liquid) and PS500 (Powder) resins (3M) were used to make fabrics from towpregs containing 50 wt% total resin (liquid and powder combined). The powder fractions were 0, 13, 21, 50 wt%. Samples were resin transfer molded from preforms made from the towpreg fabrics. Results showed that samples molded with powder‐coated preforms had improved surface finishes and reduced void contents (1.4 vs. 5%), but that the mechanical properties were not improved (transverse moduli of ∼ 7.8 Gpa and axial moduli of ∼ 100 Gpa), probably because of defects inherent in the hand‐woven towpreg fabric that was used.