Highly oriented carbon fiber-polymer composites via additive manufacturing

Additive manufacturing is distinguished from traditional manufacturing techniques such as casting and machining by its ability to handle complex shapes with great design flexibility and without the typical waste. Although this technique has been mainly used for rapid prototyping, interest is growing in direct manufacture of actual parts. For wide spread application of 3D additive manufacturing, both techniques and feedstock materials require improvements to meet the mechanical requirements of load-bearing components. Here, we investigated short fiber (0.2-0.4. mm) reinforced acrylonitrile-butadiene-styrene composites as a feedstock for 3D-printing in terms of their processibility, microstructure and mechanical performance. The additive components are also compared with traditional compression molded composites. The tensile strength and modulus of 3D-printed samples increased ~115% and ~700%, respectively. 3D-printing yielded samples with very high fiber orientation in the printing direction (up to 91.5%), whereas, compression molding process yielded samples with significantly lower fiber orientation. Microstructure-mechanical property relationships revealed that although a relatively high porosity is observed in 3D-printed composites as compared to those produced by the conventional compression molding technique, they both exhibited comparable tensile strength and modulus. This phenomenon is explained based on the changes in fiber orientation, dispersion and void formation.