Study on the fiber orientation during compression molding of reinforced thermoplastic composites

In this study, effect of fiber morphology on orientation is evaluated. Therefore, intersection angle for chopped strand, fiber length, and structure of fiber mat is changed to make the corresponding specimens and the relationship between compression ratio and fiber orientation is derived. Factors for controlling flow of glass fiber are glass fiber and matrix. 3 types of specimens, they are heated in oven as blank. Secondary hot press is applied. During compression molding, flow of test specimen is restricted to longitudinal direction. Measurement area for fiber orientation is 50 mm × 50 mm area in length of molded part, and the image is processed to confirm fiber orientation function. Fiber orientation function value, which is an indicator for directionality of fiber, is increased along with longer fiber length and higher compression ratio. Higher needle punching number induces tangling of fibers, and less fiber orientation function can be achieved. Fewer needles punching number results the less interference between fibers and fiber orientation function is increased accordingly. Fiber orientation angle, an indicator for fiber directionality in composite, can be empirically estimated according to compression ratio and fiber morphology using the derived equations.