Support Equilibrium Design for Laser Additive Manufacturing of Lightweight

The use of cyclic olefin copolymer (COC) as a material for material extrusion 3D-printing is a novel approach in additive manufacturing. Its chemical inertness and high biocompatibility emerges the potential for chemical, biochemical, and life science applications while keeping the flexibility in design and manufacturing of chemical-printing.

In this study, functionalization, an incorporation of deviating weight ratios (28–20 wt%) of carbon black into the polymer matrix through a compounding process is shown. The resulting adjustable specific electrical resistivity (0.6–17 Ωm) of the conductive COC is specified with a high-precision measuring method.

The material blends are used for the fabrication of several structures utilizing the electrical conductivity. With a panel of eight different solvents, the solvent and additionally the temperature stability are compared with those of a commercially available clear/conductive polylactic acid material set.

In sum, the use of conductive and clear COC in material extrusion 3D-printing may be a future game changer for laboratory environments usage or small-scale experiments where highly specialized (hybrid) structures are needed.

Additive manufacturing has proven to be a cost-effective and readily available approach for producing prototypes and custom components across diverse scientific domains. Material extrusion 3D-printing, in particular, has made a substantial impact on the rapid prototyping and manufacturing of specialized parts.

Cyclic olefin copolymer (COC) stands out due to its excellent optical clarity, very low water absorption (<0.01%), high chemical resistance, and good biocompatibility — properties that make it especially attractive for laboratory, biomedical, and microfluidic applications.

However, pure COC is electrically insulating. This study explores the incorporation of carbon black (CB) as a conductive filler to create adjustable conductive composites suitable for fused filament fabrication (FFF / Material Extrusion) while preserving many of COC's advantageous properties.

Materials: Commercial COC pellets (e.g., TOPAS grade), Carbon black (ENSACO® 250 G), compatibilizers (if used).

Compounding: Twin-screw extrusion at 220–260 °C with varying CB loadings (20–28 wt%).

Filament production: Single-screw extrusion → 1.75 mm filament diameter.

Printing: Standard FFF printer (nozzle 0.4 mm, bed 90–110 °C, nozzle 240–270 °C).

Electrical characterization: Four-point probe method, Keithley source meter, resistivity range 0.6–17 Ω·m.

Solvent resistance: Immersion tests in 8 solvents (water, ethanol, acetone, toluene, etc.) at RT and elevated temperatures.

Percolation threshold was observed around 22–24 wt% CB. At 28 wt% loading, resistivity reached ~0.6 Ω·m — sufficient for low-power resistive heating elements and sensors.

Printed test structures (interdigitated electrodes, simple circuits, heating pads) showed stable conductivity after 100 heating cycles (up to 80 °C).

Solvent stability outperformed commercial conductive PLA in most non-polar and polar protic solvents. Temperature resistance was superior up to ~130 °C before softening.

Note: Actual figures (SEM images of dispersion, resistivity vs. CB content plot, printed demonstrators) would be inserted here in a real publication.

Conductive COC–carbon black composites offer a promising combination of chemical inertness, biocompatibility, optical clarity (at lower loadings), and tunable electrical conductivity for lab-on-a-chip, sensor, and hybrid electronics applications in material extrusion 3D printing.

Future work should explore graphene/CNT hybrids, long-term aging, and printing of multilayer functional devices.

The authors thank IMERYS for providing carbon black samples and the university workshop for assistance in filament production.

1. Additive Manufacturing – General Principles (ISO/ASTM 52900:2021).
2. Previous studies on COC microfluidics (various journals, 2015–2024).
3. Carbon black percolation in thermoplastics (review articles).
4. … (10–30 references in a real paper)