Method to incorporate particles into continuous 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. Incorporation of fillers in resin systems is the state of the art for continuous fiber-reinforced polymers. However, this procedure shows disadvantages, such as the filtration effects of the fibers at certain particle sizes and relatively low-particle volume content. To address these issues, this study introduces and evaluates a new methodology to add 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 by comparing the infiltration quality throughout the whole process sequence. For this, the quality of the process is measured by analyzing different samples with incorporated particles of iron alloys that vary in size and shape. In addition, different filler volume contents in the roving are reached ranging from 10 to 85 vol.% and are correlated with 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.