FDM – type 3D printing has greatly increased in recent years but there is still a demand for stronger and stiffer materials. The objective of this work is to extrude and test various types of thermoplastic composite filament to be used for 3D printing. ABS thermoplastics was combined with various lengths of fiberglass. Using these thermoplastic composites several specimens were prepared per ASTM D638 by compression molding and tested. The fiberglass was introduced to increase mechanical strength and stiffness of the thermoplastic filament. Three types of fiber sizing were evaluated, the original epoxy-based sizing, an alkoxysilane Gelest sizing, and a water-based Michelman sizing. One hundred specimens were fabricated from composite material. Specimens varied by sizing, by fiberglass lengths, and by fiberglass volume fraction. Out of all the specimens tested, those with Michelman sizing produced the most consistent and overall best bonding. The Gelest sizing produced the highest and lowest values. Epoxy sizing produced almost as good results, and no sizing was worst. FDM thermoplastic filament of 1.75 mm diameter was extruded, and was used on a ROBO 3D FDM printer to 3D print objects. Mechanical strength and stiffness were not improved as expected because fiber lengths were much shorter than advertised. Other possible reasons include incomplete mixing of materials, processing errors, voids in specimens, and improper treatment of fibers with sizing.
