A preliminary study of conductive coating on printable poly(lactic acid) and poly(ethylene terephthalate glycol) polymers with graphite by laser beam

This work aims to create a composite material based on a polymeric substrate with a conductive graphite surface by additive manufacturing to create mechanical elements that can be used to construct electrical sensors. The components are fabricated with poly(lactic acid) (PLA) and poly(ethylene terephthalate)-glycol (PET-G), a sustainable and conventional polymer, which are polymers widely used in fused deposition material. Powdered graphite was deposited on the surface using a laser scan that melts the part's surface. Mechanical and electrical characterization were performed through tensile tests and electrical resistivity measurements. The mechanical tests showed a slight decrease in Young's modulus of PLA vs. coated-PLA from 0.63 to 0.59 GPa, whereas no significant mechanical difference was found for PET-G vs coated PET-G. The Gauge factors for coated-PLA and coated-PET-G are 0.17 and 0.08, respectively; coated-PLA is more sensitive than the coated-PET-G strain gauge. This coating provides an electrical behavior that can be proposed for constructing strain gauges, which can be used to measure the strain in metallic mechanical elements.