Integration of graphene in poly(lactic) acid by 3D printing to develop creep and wear-resistant hierarchical nanocomposites

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 (approximate to 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. (c) 2017 Society of Plastics Engineers