抄録
This paper discusses the effect of fiber orientation upon weld strength of short-fiber-reinforecd polymer composites. The fiber orientations of an injection-molded parent and weld were studied by microscorpic methods. The appearence of fiber orientation in the mold was named either a flowerlike pattern in a wide area or a volcanolike pattern in a narrow area. In addition, whether the matrix or the orientation of glass fiber at weld regions has the greater effect on weld strength was discussed. The tensile strength of the parent and weld is greatly affected by fiber orientation within the angle of 45o, but over 45O the effect of matrix properties on strength is greater than that of fiber orientation. The polymer composite material used in this experiment is a polycarbonate with amorphous structure, such as general engineering plastics, including 30% short glass fibers. The specimen used is the dumbbell-type tensile and three-point bending specimen with a weld line, made by means of double-gate injection molding. The microtoming technique was used for slicing ultrathin sections from molded polymer parts. Microstructural analysis of fiber orientation at the injection weld was carried using a light-transmission microscope and an image analyzer.
