Application of thermotropic liquid crystalline polymer reinforced acrylonitrile butadiene styrene in fused filament fabrication

Abstract

In this work, acrylonitrile butadiene styrene (ABS) was reinforced with a thermotropic liquid crystalline polymer (TLCP) for use in Fused Filament Fabrication (FFF). As ABS and the selected TLCP do not exhibit overlapping processing temperatures, the composite filaments were generated using a dual extrusion technology which allows processing of such matrix-TLCP combinations. The 40.0 wt.% TLCP/ABS filaments exhibited a tensile strength and modulus of 169.2 ± 4.0 MPa and 39.9 ± 3.7 GPa, respectively, due to a nearly continuous reinforcement of the filament. The postprocessing of the filaments in FFF was carried out below the melting temperature of the TLCP, which allowed the printer to take sharp turns despite having nearly continuous reinforcement. On the contrary, the use of commercially available continuous carbon fiber/nylon 6 was found to avoid printing regions which required sharp turns. On printing with the 40.0 wt.% TLCP/ABS filaments, the tensile strength and modulus in the print direction were 74.9 ± 2.4 MPa and 16.5 ± 0.8 GPa, respectively. The compression molded specimens exhibited a tensile strength and modulus of 79.6 ± 4.4 MPa and 12.3 ± 1.2 GPa, respectively, whereas the injection molded specimens exhibited 51.3 ± 3.0 MPa and 4.5 ± 0.1 GPa, respectively.