A novel method to incorporate particles into endless fiber-reinforced polymers with process evaluation and analysis of the filler distribution

To functionalize and adjust certain material properties the addition of micro- or nanoparticles to composite materials is a well-known method. Various filler materials and particle sizes can be used and added to different matrix materials to improve for instance mechanical, thermal, electrical or electromagnetic properties. Filler incorporation in resin systems is the state of the art for endless fiber reinforced polymers. However, this procedure shows disadvantages, such as filtration effects of the fibers at certain particle sizes and relative low particle volume content. To address these issues, this study introduces and evaluates a new methodology for adding particles to endless fiber reinforced plastics. In contrast to adding particles to a matrix, the presented process attaches fillers to fibers via a wet-infiltration method. The procedure is evaluated in terms of process stability and reproducibility. The investigation is carried out comparing the infiltration quality throughout a whole process sequence. For this, the process quality is measured by analyzing different samples with incorporated particles of iron alloys, varying in particle size and shape. Also, different filler volume contents in the roving ranging from 10 vol.% to 85 vol.% are reached and correlated to the process parameters. Another focus point in this study, is the filler distribution. The samples are evaluated and compared in terms of filler distribution, both macroscopically and microscopically.