Low latency, electrically conductive path for low-power electronics, obtained by laser sintering of carbon-enhanced polypropylene composites

This study investigated the laser-induced fabrication of conductive pathways in a technical-grade polypropylene (PP) masterbatch containing glass fibers, hollow glass microspheres, and carbon black at 10, 20, and 0.4–0.5 wt%, respectively. Graphene nanoplatelets (GNPs) and graphene oxide (GO) nanosheets were synthesised and added to the masterbatch composition, as individual or combined fillers. GNP loadings in the resulting compounds were tuned to improve mechanical properties, but not to impart significant electrical conductivity in the resulting composite materials. The different loadings (2.5 wt% GNPs, 2.5 wt% GO or 2.5 wt% GO with 1.5 wt% GNPs, respectively) were confirmed in composition by thermogravimetric analysis (TGA). A beneficial effect of GNP and GO on the mechanical properties of the composite was confirmed using elongation and three-point flexural tests. Among the series of formulations, the PP composite loaded with 2.5 wt% GNPs exhibited the best mechanical properties and was selected for laser processing experiments. Laser scribing parameters, such as optical power (W) and scribing speed (mm/s), were found to significantly influence the morphology, composition, and electrical properties of laser-scribed paths. Lowest sheet resistance (0.3 Ohm/sq) values were achieved with high laser power and low writing speeds. Morphological, compositional, and structural analyses of the scribed paths were conducted using field-emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), and micro-Raman spectroscopy. These analyses revealed that the scribed tracks were not homogeneous in composition, containing isolated graphene sheets and an accumulation layer of carbon black (CB) covering the entire irradiated path. Interestingly, the glass fibers and hollow glass microspheres provided a good support for the accumulation of carbon black along the laser irradiated paths. More interestingly, this accumulation layer of agglomerated CB was found to provide a continuous conductive network for effective electron transport. We also explored the capabilities of these laser-scribed tracks to transmit electrical signals, assessing their performance in comparison to standard USB cables. Our findings indicate that the laser-scribed tracks achieved comparable latency and data transfer rates to traditional USB cables. Moreover, no errors were observed during data transfer, and the phase correlation necessary for serial communication was preserved. These results demonstrate that laser-scribed tracks can reliably support data transfer operations, offering a simple route of embedding components through CO2 laser irradiation processing. By laser-treating a rectangular area, we also fabricated a polymer-based electric heater with high thermal homogeneity and a linear voltage-temperature dependence.