Performance Evaluation of CNT Reinforcement on Electroless Plating on Solid Free-Form-Fabricated PETG Specimens for Prosthetic Limb Application

The utility of polymers in the present decade is consistently increasing, giving scope to many applications from automobiles to prosthetics. Polymers used for solid free-form fabrication (SFFF), also known as 3D printing, comprise a quick fabrication process adopted by many industries to increase productivity and decrease the run time to cope with the market demands. In this research work, pure polyethylene terephthalate glycol (PETG) and multi-walled carbon nanotube (MWCNT)-PETG with an electroless metal layer coating and without a coating are discussed. The effect of the electroless metal layer coating on the reinforced PETG-MWCNT results in improved mechanical, tribological, and other surface properties. Pure PETG was incorporated with MWCNT nanofillers at 0.3 wt.% and extruded as a filament through a twin screw extruder with a 1.75 mm diameter and printed on ASTM standards. Tensile testing was performed on all four types of un-coated pure PETG, PETG-MWCNT, and metal-layer-coated PETG and PETG-MWCNT with a coating thickness of 26, 32, 54, and 88 μm. Dynamic mechanical analysis (DMA) showed that the coated PETG-MWCNT had the highest storage and loss modulus. The heat deflection temperature was improved to 88 °C for the coated PETG-MWCNT. The wear volume against the sliding distance at a load of 40, 50, and 60 N showed that the coefficient of friction decreased with an increase in the load. The scratch test results revealed the lowest penetration depth and lowest friction coefficient for the coated PETG-MWCNT sample. The water contact angle test showed that a greater coating thickness makes the sample surface more hydrophobic, and the microhardness test indicated that the indentation hardness value for the PETG-MWCNT was 92 HV. The study revealed that the metal-layer-coated PETG-MWCNT had better performance compared to the other specimens due to a good metal layer bonding on the PETG substrate. It was concluded that adding MWCNTs to a metal layer electroless coating improved the surface and mechanical properties of the PETG, and this may be suitable for many applications.