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Mechanical Characterizations of 3D-printed PLLA/Steel Particle Composites

Department of Mechanical & Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
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Materials 2019, 12(1), 1; https://doi.org/10.3390/ma12010001
Received: 29 October 2018 / Revised: 1 December 2018 / Accepted: 6 December 2018 / Published: 20 December 2018
(This article belongs to the Special Issue Polymer Composites and Interfaces)
The objective of this study is to characterize the micromechanical properties of poly-l-lactic acid (PLLA) composites reinforced by grade 420 stainless steel (SS) particles with a specific focus on the interphase properties. The specimens were manufactured using 3D printing techniques due to its many benefits, including high accuracy, cost effectiveness and customized geometry. The adopted fused filament fabrication resulted in a thin interphase layer with an average thickness of 3 µm. The mechanical properties of each phase, as well as the interphase, were characterized by nanoindentation tests. The effect of matrix degradation, i.e., imperfect bonding, on the elastic modulus of the composite was further examined by a representative volume element (RVE) model. The results showed that the interphase layer provided a smooth transition of elastic modulus from steel particles to the polymeric matrix. A 10% volume fraction of steel particles could enhance the elastic modulus of PLLA polymer by 31%. In addition, steel particles took 37% to 59% of the applied load with respect to the particle volume fraction. We found that degradation of the interphase reduced the elastic modulus of the composite by 70% and 7% under tensile and compressive loads, respectively. The shear modulus of the composite with 10% particles decreased by 36%, i.e., lower than pure PLLA, when debonding occurred. View Full-Text
Keywords: particle composite; 3D printing; fused filament fabrication; finite element method; micromechanics; poly-l-lactic acid (PLLA); nanoindentation; mechanical properties particle composite; 3D printing; fused filament fabrication; finite element method; micromechanics; poly-l-lactic acid (PLLA); nanoindentation; mechanical properties
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MDPI and ACS Style

Mozafari, H.; Dong, P.; Hadidi, H.; Sealy, M.P.; Gu, L. Mechanical Characterizations of 3D-printed PLLA/Steel Particle Composites. Materials 2019, 12, 1.

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