Polypropylene composites with natural fibers and wood – General mechanical property profiles

Natural Fiber Composites (NFCs) and Wood Polymer Composites (WPCs) based on polypropylene (PP) have gained increasing interest over the past two decades, both in the scientific community and in industry. Meanwhile, a large number of publications is available, but yet the actual market penetration of such materials is rather limited. To close the existing gap between scientific and technical knowledge, on the one hand, and actual market applications, on the other, it is the purpose of this paper to analyze the current state of knowledge on mechanical performance profiles of injection molded NFCs and WPCs. As the composite properties are a result of the constituent properties and their interactions, special attention is also given to mechanical fiber/filler properties. Moreover, considering that NFCs and WPCs for a variety of potential applications compete with mineral reinforced (mr; represented in this study by talc), short glass fiber (sgf), long glass fiber (lgf) and short carbon fiber (scf) reinforced PP, property profiles of the latter materials are included in the analysis. To visualize the performance characteristics of the various materials in a comparative manner, the data were compiled and illustrated in so-called Ashby plots. Based on these comparisons, an assessment of the substitution potential of NFCs and WPCs is finally performed, along with a discussion of still open issues, which may help in guiding future material development and market application efforts.