Conveyor fused deposition modelling (CFDM) 3D printing of graphene (GR)/polylactic acid (PLA) composite filament offers a unique capability to manufacture tailorable honeycomb structures which can be designed and optimized for specific applications. Among the various filaments that can be used for 3D printing, PLA, carbon black (CB)/PLA, and GR/PLA filaments were collected and then examined by differential scanning calorimetry (DSC), thermal gravity analysis (TGA), and Raman spectra. A stereolithography (STL) file with a 3D honeycomb structure model was prepared and transformed into a G-code file using a G-code generator. The extrusion conditions for CFDM 3D printing were controlled by infill and print speed. PLA, CB/PLA, and GR/PLA composite honeycomb samples were manufactured by 3D printing based on FDM using PLA, CB/PLA, and GR/PLA filaments. CFDM 3D printed honeycomb samples prepared by PLA, CB/PLA and GR/PLA filament were analyzed for morphology, surface resistance, electrical heating properties. For the 3D printed honeycomb structure sample using CB/PLA and GR/PLA, the optimum condition was set up 230 °C and 220 °C respectively of the printer temperature, 50 °C of bed temperature, and 30 mm/s of printer speed. Surface resistivity of honeycomb structure sample using CB/PLA and GR/PLA is about 299.0 Ω/sq and 118.0 Ω/sq. The maximum surface temperature of honeycomb structure sample using CB/PLA and GR/PLA is ca. 78.7 °C and 143.0 °C applied to 25 V.

An electro-conductive para-aramid knit was manufactured by a dip-coating in a graphene/waterborne polyurethane(WPU) composite for confirming to use as a fabric heating element applicable to a protective clothing requiring durability. The para-aramid knit was dipped in 8 wt% graphene/WPU composite solution up to five-coat cycles. As a result of electro-conductive textile by number of dip-coating cycles, the electrical, and specifically electrical heating performances were increased number of cycles from one to five. The sample with the best electrical and electrical heating performance was the five-coat sample, and to improve those properties it was hot-pressed at 100 °C, 120 °C, 140 °C and 160 °C. After hot pressing, the entire surface of the sample was filled with graphene/WPU composite and indicated smoothly surface, thus the electrical and electrical heating performance was improved than the five-coat sample. The best performance of was indicated hot-pressed at 140 °C, with a surface resistivity and capacitance of 7.5 × 10⁴ Ω/sq and 89.4 pF, respectively. When a voltage of 50 V was applied, the surface temperature reached 54.8 °C. The five-coat sample with hot-pressed at 140 °C could be applied to a heat-resistant para-aramid knit glove with the touch screen of a mobile phone and electric heating performance.

In this study, a series of bio-based thermoplastic polyurethane (TPU) was synthesized via the solvent-free one-shot method using 100% bio-based polyether polyol, prepared from fermented corn, and 1,4-butanediol (BDO) as a chain extender. The average molecular weight, degree of phase separation, thermal and mechanical properties of the TPU-based aromatic (4,4-methylene diphenyl diisocyanate: MDI), and aliphatic (bis(4-isocyanatocyclohexyl) methane: H₁₂MDI) isocyanates were investigated by gel permeation chromatography, Fourier transform infrared spectroscopy, atomic force microscopy, X-ray Diffraction, differential scanning calorimetry, dynamic mechanical thermal analysis, and thermogravimetric analysis. Four types of micro-phase separation forms of a hard segment (HS) and soft segment (SS) were suggested according to the [NCO]/[OH] molar ratio and isocyanate type. The results showed (a) phase-mixed disassociated structure between HS and SS, (b) hydrogen-bonded structure of phase-separated between HS and SS forming one-sided hard domains, (c) hydrogen-bonded structure of phase-mixed between HS, and SS and (d) hydrogen-bonded structure of phase-separated between HS and SS forming dispersed hard domains. These phase micro-structure models could be matched with each bio-based TPU sample. Accordingly, H-BDO-2.0, M-BDO-2.0, H-BDO-2.5, and M-BDO-3.0 could be related to the (a)—form, (b)—form, (c)—form, and (d)—form, respectively.