Study on mechanical characteristics of glass fiber-reinforced polycarbonate LFT-D for codico structures

Long fiber thermoplastic (LFT) materials can be compounded in an effective LFT direct (LFT-D) process. Polycarbonate (PC) is used in various applications for example in and around battery enclosures for electro mobility. Reinforced with glass fibers (GF), PC exhibits solid mechanical properties and is a promising and novel addition to the material portfolio of the LFT-D process considering current industry demands. Combining continuous (Co) and discontinuous (DiCo) fiber reinforced polymers (FRP) according to their respective strengths enables unique design freedom to this class of materials. LFT-D materials can be used as the DiCo phase. The semi-finished material of the LFT-D process, called plastificate, is placed in the charge area and will fill the mold during compression molding forming the flow area. These areas are very distinct in their microstructure.
In this work, PC GF LFT-D is produced at various process parameter sets and molded into plates. Screw speed and fiber roving amount is varied. Plates were characterized for their fiber mass fraction, fiber length and tensile properties. Fiber mass fraction as well as fiber length are very homogenous over charge and flow area. Tensile properties are characterized in the flow area in eight adjacent positions. A strong influence of sample position on modulus and strength, resulting in deviations of up to twenty-five percent from highest to lowest value, is present. Running the extruder at increasing screw speeds improves Young’s modulus as well as tensile strength.