Effect of Carbon Fiber Orientation on the Physical Properties and Crystallization Behavior of Nylon 66/Carbon Filler Composites

In this study, we investigated the crystallization behavior and the relationship between the fiber orientation and physical properties as a function of specimen molding method such as compression and injection molding when nickel coated carbon fiber (Ni-CF) was applied to nylon66/carbon filler composite. Carbon black (CB) and multi-walled carbon nanotubes (MWCNT) were used as the carbon fillers, and the nylon66/CB/CNT/Ni-CF composites were extruded at a die temperature of 280 degrees C and a screw speed of 150 rpm in a twin screw extruder. Compared with pure nylon 66, the crystallization temperature of the composite increased and the crystal size decreased. The results can be interpreted as a result of the carbon filler acting as a heterogeneous nucleating agent, resulting in the formation of many small crystals compared to nylon 66. In the case of injection molded specimens, the fibers were oriented in the direction of injection, which is advantageous to the shielding of the reflection, and the electromagnetic shielding performance and mechanical properties were increased. However, the surface resistance value was rather increased and the electrical characteristic was decreased because the electrical networking in the vertical direction of the flow is decreased.