fraction on thermal conductivity. Despite this limitation, the thermal conductivity values provided can be used to engineer thermal conductivity into 3-D printed parts with these PLA-based composites. Finally, several high-value applications of such 3-D printed materials that look metallic, but have low thermal conductivity are reviewed.

Cycloaliphatic epoxies (CEs) are commonly used for structural applications requiring improved resistance to elevated temperatures, UV radiation, and moisture relative to other epoxy materials. Accurate and efficient computational models can greatly facilitate the development of CE‐based composite materials for applications such as Aluminum Conductor Composite Core high‐voltage power lines. In this study, a new multiscale modeling method is developed for CE resins and composite materials to efficiently predict thermal properties (glass‐transition temperature, thermal expansion coefficient, and thermal conductivity). The predictions are compared to experimental data, and the results indicate that the multiscale modeling method can accurately predict thermal properties for CE‐based materials. For 85% crosslink densities, the predicted glass‐transition temperature, thermal expansion coefficient, and thermal conductivity are 279 °C, 109 ppm °C−1, 0.24 W m−1 K−1, respectively. Thus, this multiscale modeling method can be used for the future development of improved CE composite materials for thermal applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46371.

Cycloaliphatic epoxy (CE) resin systems are of primary interest in applications that require improved resistance to harsh conditions relative to other epoxy systems.Because other epoxy systems have demonstrated improved resistance to hydrothermal aging with the addition of carbon-based nanoparticle reinforcement, it is expected that the hydrothermal resistance of CE resins will likewise be improved with incorporation of nanoparticles. Therefore, the objective of this study is to determine the influence of graphene nanoparticles (GNP) on the hydrothermal aging resistance of CE resins. CE specimens are fabricated with varying levels of GNP and exposed to elevated temperatures and moisture levels for varying amounts of time up to 400 hours. The results from flexure and dynamical-mechanical testing indicate that the addition of GNP provides modest improvements in the stiffness and glass transition temperature for all aging levels, while the strength is improved for aging times below 400 hours.

Polyetheretherketone (PEEK)‐based composites are used in aerospace applications due to their high mechanical strengths at temperatures >250°C, excellent chemical resistance properties, and outstanding dimensional stability. In this work, varying amounts of three different carbon fillers (carbon black [CB], graphene nanoplatelets [GNP], and carbon fiber [CF]) were added to PEEK to produce conductive composites for aerospace applications. Researchers extruded, injection molded, and performed electrical and thermal conductivity (TC) and tensile tests on GNP/PEEK, CB/PEEK, CF/PEEK, and CB/CF/PEEK composites. Five formulations could be used for electrostatic dissipative applications: 15 wt% GNP/PEEK, 20 wt% CF/PEEK, 2.5 wt% CB/10 wt% CF/PEEK, and 2.5 wt% CB/20 wt% CF/PEEK. Seven formulations could be used for electrically conductive applications: 30 wt% CF/PEEK, 5 wt% CB/PEEK, 7.5 wt% CB/PEEK, 10 wt% CB/PEEK, 2.5 wt% CB/30 wt% CF/PEEK, 5 wt% CB/30 wt% CF/PEEK, and 7.5 wt% CB/30 wt% CF/PEEK. The most conductive composite produced was 7.5 wt% CB/30 wt% CF/PEEK, which had an electrical resisitivity (1/electrical conductivity) of 0.56 Ω cm, a TC twice that of the neat PEEK, a tensile strength of 145 MPa, and a tensile modulus of 18.4 GPa. Per the authors' knowledge, properties on these GNP/PEEK, CB/PEEK, and CB/CF/PEEK composites have not been previously reported in the open literature. POLYM. COMPOS., 39:E807–E816, 2018. © 2016 Society of Plastics Engineers

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