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An electrostatic spraying technique was used to synthesize 3D graphene foam (GrF)‐reinforced polyurethane (PU) composites. Glass transition temperature (Tg) of PU increased from 120 to 148°C after 3.3 vol% GrF addition. Strong interfacial bonding accounts for the improvement in Tg of PU‐GrF composites. Energy dissipation behavior is probed at multiple load scales to examine the intrinsic and structural damping characteristic. Micro‐scale damping at 1 mN and 1,000 Hz exhibited loss tangent value (tan δ), which is 200% higher and 3 times faster than PU. Nano dynamic mechanical analysis of PU‐3.3 vol% GrF composite demonstrated up to 383% tan δ improvement than of PU at 5 μN dynamic load. Physical mechanisms including rippling effect and weak van der Waals forces in graphene account for the high energy dissipation of PU‐GrF composite. This study suggests that PU‐GrF nanocomposites have the potential to serve as a good damping material in vibrating systems. POLYM. COMPOS., 40:E1862–E1870, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) and graphene reinforced polylactic acid (PLA‐graphene) composites have been fabricated by three‐dimensional (3D) fused deposition modeling (FDM) printing. Indentation creep resistance was analyzed in terms of the strain‐rate sensitivity index of PLA (0.11) and PLA‐graphene (0.21). Enhanced creep resistance in PLA‐graphene is attributed to the restriction of the polymeric chains by graphene, caused by low strain rates identified during secondary creep. The tribological properties of PLA and PLA‐graphene composites were evaluated by ball‐on‐disk wear tests. Wear resistance was increased by a 14% in PLA‐graphene as compared to PLA. A two‐stage coefficient of friction (COF) behavior has been observed for PLA‐graphene. Initially, PLA‐graphene exhibits a 65% decrease in COF as compared to PLA. During the second stage, PLA‐graphene approached similar COF behavior and value of PLA (∼0.58). PLA‐graphene composites have shown significant improvement in creep and wear resistance demonstrating 3D printing to be a novel manufacturing route. POLYM. COMPOS., 39:3877–3888, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]