FLOWABILITY OF DISCONTINUOUS CARBON FIBER REINFORCED THERMOPLASTICS

Carbon fiber reinforced thermoplastics (CFRTP) is an important engineering material which has much lower weight than metallic materials with the same strength and toughness, thus the energy consumption can be reduced significantly by using CFRTP as a structural material for transportation. Compared with continuous CFRTP, discontinuous CFRTP requires much lower molding pressure and has higher capacity to form parts with smaller-size or more complex shape, which benefits the reduction of cost and improvement of production efficiency, so it has much more potential to be used for mass production in industrial application. During the fabrication of CFRTP, the flowability of fillers in CFRTP composite is a quite important factor since it decides the mechanical properties of CFRTP materials and molding pressure during manufacture, hence product's reliability and initial investment. In this paper, the flowability of ultra-thin chopped carbon fiber tape reinforced thermoplastics (UT-CTT), a kind of discontinuous CFRTP, was investigated. The influence of molding pressure and holding time on the flowability of UT-CTT was investigated first by using mold with ribs. Then the cross section of ribs was observed by microscope in order to characterize the flow behavior of fibers during molding process. The results show that the flowability of UT-CTT changes drastically with different pressure and holding time. Under the conducted pressure, fiber tapes successfully flew into the ribs as U-shape without break and formed a laminate structure as flat part.