Abstract
For the purpose of fabricating electrically conductive composites via the fused filament fabrication (FFF) technique whose properties were compared with injection-moulded properties, poly(lactic acid) (PLA) and polycaprolactone (PCL) were mixed with different contents of graphene nanoplatelets (GNP). The wettability, morphological, rheological, thermal, mechanical, and electrical properties of the 3D-printed samples were investigated. The microstructural images showed the selective localization of the GNPs in the PCL nodules that are dispersed in the PLA phase. The electrical resistivity results using the four-probes method revealed that the injection-moulded samples are insulators, whereas the 3D-printed samples featuring the same graphene content are semiconductors. Varying the printing raster angles also exerted an influence on the electrical conductivity results. The electrical percolation threshold was found to be lower than 15 wt.%, whereas the rheological percolation threshold was found to be lower than 10 wt.%. Furthermore, the 20 wt.% and 25 wt.% GNP composites were able to connect an electrical circuit. An increase in the Young’s modulus was shown with the percentage of graphene. As a result, this work exhibited the potential of the FFF technique to fabricate biodegradable electrically conductive PLA-PCL-GNP composites that can be applicable in the electronic domain.
Highlights
The use of plastics is significantly increasing in all applications [1]
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The length of the plateau extended to higher frequencies with the increase in the percentage of graphene; this emphasizes the formation of filler networks and the entrapment of the increased number of filler–filler interactions, as well as the reduction in the chain mobility of the polymers located near the graphene particles
Summary
Biopolymers have recently become of great interest due to the high demand for sustainable materials possessing eco-friendly characteristics. Poly(lactic acid) or polylactide (PLA) is an aliphatic thermoplastic polyester that is biobased, biodegradable, biocompatible, and compostable. It is characterized by important mechanical properties, such as Young’s modulus in the 3–4 GPa range and tensile strength in the 60–70 MPa range [3]. PCL is a semi-crystalline aliphatic polyester that is biodegradable and biocompatible but oil-derived. Due to the different mechanical and thermal properties of both polymers, their mixture can be a material with well-balanced properties [4]
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