PREPREG PROCESS ANALYSIS

A description of the hot-melt prepreg process was developed by couplin g resin matrix flow at the coating and impregnation zones with heat tr ansfer considerations. Both bismaleimide (BMI) and epoxy resin systems were used as matrices, with continuous carbon fiber reinforcement. Fo r the laboratory scale prepregger utilized in this study, the thicknes s of the resin film produced in a doctor blade was approximately 63% o f the blade distance, showing good agreement with experimental data. I n addition, the measured heat transfer coefficient between prepreg and atmosphere indicated that surface convective resistance is large comp ared to the internal conductive resistance and thus the chill plate in the prepregging operation plays an important role in determining prep reg quality. By formulating an analytical methodology in terms of the ''Prepreg Flow Number'' (PFN) that combined important operating parame ters (e.g., temperature, pressure, and production rate), a temperature -pressure-velocity superposition was confirmed for the prepregging pro cess. In addition, the model could easily be extended to different sca les and types of prepregging processes with the aid of dimensionless p arameters that are quite descriptive of the operating conditions emplo yed in prepreg manufacturing.