DEVELOPMENT OF A THEORETICAL-MODEL FOR A SOLVENT-TYPE PREPREG MANUFACTURING PROCESS

This paper presents a theoretical study of the impregnation of continu ous fiber or cloth with thermosetting resin matrix materials. A model is developed to describe the resin, the volatile content and the coate d resin thickness as functions of impregnation velocity for a solvent- type, vertical impregnating process. A power law is employed to accoun t for the effect of shear rate on the resin velocity in the model. Res ults are obtained methodically through the separation of variables. A dimensionless number, called the impregnation number, is derived which expresses the relative importance among the viscous, inertial and gra vity forces in the impregnation process. It is found that the dimensio nless number is important in characterizing the maximum possible resin content for a given condition, and that an increase in the resin visc osity is much more effective than an increase in the impregnation velo city in achieving higher resin content. The volatile content is contro lled by a combination of the impregnation velocity and the oven length . The predicted volatile contents agree well with the experimental res ults for a 177-degrees-C prepreg. The model is valid for predicting vo latile content in the practical impregnation process.