Effects of Direct Fiber Feeding Injection Molding on the Structure and Properties of Fiber Reinforced Polypropylene Composites

繊維強化ポリプロピレン複合材料の構造と性質に及ぼす直接繊維投入射出成形の影響

2018-09-25

2018-09-25

For a further extending the application of short fiber reinforced polymer composites, pultrusion and direct in-line long fiber thermoplastic compounding technology are used in industry. However, those methods have some limitations such as low efficiency, high investment cost, and unstable quality. In this thesis, the main purpose is to obtain a higher performance fiber reinforced polypropylene composite by using a new method known as direct fiber feeding injection molding (DFFIM) to avoid the limitations mentioned above. First, the effect of process parameters including the number of fiber bundles, the number of fibers altogether feeding and pellets feeding speed on the mechanical properties of glass fiber reinforced polypropylene composites fabricated by DFFIM are discussed. The fracture surfaces were observed by scanning electron microscopy. Then, the tensile properties of glass fiber/carbon fiber reinforced polypropylene hybrid composites fabricated by DFFIM were predicted by considering fiber length and orientation using the modified Tsai-Hill criterion. The accuracy of the modified Tsai-Hill criterion was compared with other methods and then the most suitable approach to predict modulus and strength was determined. Moreover, the structure and interfacial shear strength were evaluated based on the skin-core-skin structure and modified Kelly-Tyson equation. The fiber dispersion status and interfacial shear strength (IFSS) of DFFIM hybrid composites in different layers were examined according to the skin-core-skin structure. The fiber dispersion status was evaluated qualitatively by scanning electron microscopy and quantitatively by the fiber distribution index (FDI). The IFSS between fibers and polypropylene of different composites in the skin layers and the core layer are discussed by considering fiber length and orientation distributions. Lastly, two types of vented injection molding machines with a different check ring and mold were used for manufacturing specimens. The fiber lengths were analyzed to identify the most suitable check ring and mold for the DFFIM process. Polyamide 6 and maleic anhydride-grafted polypropylene were incorporated as the auxiliaries to improve the interfacial bonding between the fibers and matrix and to enhance the stress transfer in the DFFIM composites.

博士（工学）

京都工芸繊維大学

14303甲第904号

http://hdl.handle.net/10212/2501

eng

ETD

18

Thesis or Dissertation

Thesis