Interfacial Shear Strength of Glass Fiber Reinforced Polymer Composites by the Modified Rule of Mixture and Kelly-Tyson Model

Four types of commercial grade glass fiber reinforced thermoplastics (GFRP) were used in this study. Polymer matrices included polycarbonate (PC), polyoxymethylene (POM), polypropylene (PP) and polyamide 6 (PA6). The contents of GF were 10%, 20% and 40%. The GFRP were fabricated to dumbbell specimens by injection molding machine. Tensile strength of the GFRP composites was carried out by tensile testing. Theoritical caluculation of interfacial shear strenght was analyzed using a modified rule of hybrid maixture (MRoHM) strength equation according to the orientation and direction of glass fiber reinforcing. The fiber orientation was characterized from the fractured surface observation by scanning electron microscope and optical microscope. The tensile strength of GFRP composites increased with incresing glass fiber contents. However, the declination of tensile strength from the prediction was attributed to the reduction of glass fibers length and fiber orientation in GFRP composites. It is interesting to report that the interfacial shear strength of GFRP composites was calulated according to the MroHM and the Kelly-Tyson model, which the interfacial shear strength of the composites increased with incresing glass fiber contents.