The Relationship between Quantitative Evaluation of Filamentization and Mechanical Properties in the LFRTP Molding

The long fiber reinforced thermoplastic (LFRTP) pellet has better mechanical properties than short fiber reinforced pellet and better moldability than stampable sheet. At present, injection molding method is mainly used for molding LFRTP pellets because of its high productivity. However, the long fiber of LFRTP pellet, whose length is same as pellet length, is degraded during processing if conventional injection molding machines are used, and as the result, the mechanical properties are not improved as expected in many cases. Therefore, a new molding process is required to make good use of LFRTP pellets. Recently, a new molding process has been developed appropriate for LFRTP pellets. It is possible for this new molding machine to make fiber length longer in the molding than universal injection molding one. However, the deterioration of the filamentization becomes the disturbance of the improvement of the mechanical property. Then, the quantification of the filamentization was tried in this study. In addition to it, the experimental strength was compared with the theory strength that considers fiber length, fiber concentration and fiber orientation.As the result, we were able to prove the effectiveness of quantification technique of the filamentization. Then, it was possible to grasp the relationship between tensile strength and filamentization, and the importance of filamentization was confirmed.