Strengthening of plasma treated 3D printed ABS through epoxy infiltration

3D printed fused deposition modeling (FDM) material parts have distinct anisotropic mechanical properties based upon their as-built print orientation. The strength of material printed perpendicular to the deposition layers can be as low as 50% of values for injection molded parts due to less than optimum interlayer fusion, limiting their use for critical applications. The focus of this work is to present a novel way of utilizing design freedoms available in FDM to improve strength in weak orientations. Vertically processed FDM ABS parts were manufactured with cavities printed perpendicular to the interlayer direction and were subsequently plasma surface treated, filled with an epoxy resin, and mechanically tested. Plasma treatment was shown to beneficially modify the surface chemistry, which resulted in a 50% improvement in shear strength over untreated specimens. Samples that underwent plasma treatment and epoxy infiltration demonstrated a 130% increase in flexural strength over that of as-printed FDM material. The failure strain was also shown to increase by two-fold. The addition of milled carbon fiber (MCF) filler within the epoxy infiltrate was also evaluated and was shown to increase the flexural modulus by as much as 76% at 10 wt% loading levels, though negligible increases in strength were observed.