Variation of the structure and permeability of tense fiber layers during impregnation with thermoplastic polymer melt

摘要

The influence of the displacements of tense fibers on the impregnation of fibrous layers with polymer melt and on the final composite structure is studied. Using computer simulation it is shown that, during impregnation, the structure of tense fibrous layers considerably changes depending on the initial arrangement and tension of the fibers. Consolidated regions formed under the melt front move inside the impregnated layer with advancing melt front. The displacement of the tense fibers as well as the formation of "washouts" favour impregnation of internal layers, but cause significant inhomogeneity of the polymer structure. The surface (on the side of melt flow) regions are more saturated by the polymer than the internal regions. A difference in the melt percolation models at various impregnation regimes is revealed. The effective permeability coefficients of a tense fiber layer are not constant, they depend on the conditions and regimes of impregnation.