MACRO-IMPREGNATION AND MICRO-IMPREGNATION PHENOMENA IN CONTINUOUS MANUFACTURING OF FABRIC REINFORCED THERMOPLASTIC COMPOSITES

Macro- and micro-impregnation of molten thermoplastic polyamide 6.6 in to glass and carbon fabrics during continuous manufacturing using a do uble belt press was investigated. Following the analytical approaches on transverse permeability of fiber bundles, a comprehensive experimen tal set-up has been derived to verify the effects of temperature bound ary conditions, resident time, consolidation pressure and fiber bundle permeability on the degree of impregnation. Samples with reinforcemen ts of glass and carbon fabrics were produced at distinct processing co nditions and the degree of impregnation was investigated by microscopi c observation and mirrored by measuring the flexural stiffness in a th ree-point bending test. Hence, contribution of particular processing p roperties on impregnation was discussed in detail and the results are to be applied to guide the manufacturing process concerning selection of appropriate raw materials and optimized processing conditions. It c ould be concluded, that the continuous manufacturing process using a d ouble belt press might basically be simulated by applying the current analytical approaches on the impregnation of fibers with thermoplastic polymers, but exhibits its own characteristics with respect to intra- bundle mechanism such as microscopic adhesion and void entrapment. (C) 1998 Elsevier Science Ltd. All rights reserved.