Biodegradable Poly(Lactic Acid) Nanocomposites for Fused Deposition Modeling 3D Printing

Abstract

3D printing by fused deposition modelling (FDM) enables rapid prototyping and fabrication of parts with complex geometries. Unfortunately, most materials suitable for FDM 3D printing are non-degradable, petroleum-based polymers. The current ecological crisis caused by plastic waste has produced great interest in biodegradable materials for many applications, including 3D printing. Poly(lactic acid) (PLA), in particular, has been extensively investigated for FDM applications. However, most biodegradable polymers, including PLA, have insufficient mechanical properties for many applications. One approach to overcoming this challenge is to introduce additives that enhance the mechanical properties of PLA while maintaining FDM 3D printability. This review focuses on PLA-based nanocomposites with cellulose, metal-based nanoparticles, continuous fibers, carbon-based nanoparticles, or other additives. These additives impact both the physical properties and printability of the resulting nanocomposites. We also detail the optimal conditions for using these materials in FDM 3D printing. These approaches demonstrate the promise of developing nanocomposites that are both biodegradable and mechanically robust.

Keywords: 3D printing; additive manufacturing (AM); carbon nanoparticles; cellulose; fused deposition modeling (FDM); poly(lactic acid) (PLA).

Figure 1

Poly(lactic acid) conformers.

Figure 2

(a) Flat, on-edge, and up right printing orientation of tensile bars. (b) Processing parameters of tensile bars. Reproduced with permission from [27], Elseveir, 2017.

Figure 3

Cellulose chemical structure.

Figure 4

Depiction of rotation and crosshatched 3D printing pattern utilized to increase mechanical properties of 3D-printed materials. Reproduced with permission from [44], Wiley, 2020.

Figure 5

Poly(lactic acid) (PLA)/copper fiber surfaces (A,B) before laser treatment showing gaps, voids, and uneven surface morphology and (C) after 5 W laser treatment with a 175 µm beam. Reproduced with permission from [49], Wiley, 2020.

Figure 6

Compatibilized magnesium nanoparticle PLA filaments. (A) Fused deposition modelling (FDM) 3D-printed scaffold, (B) layer structure of scaffold, (C) cross section of individual layer showing magnesium dispersion. Reproduced with permission from [53], Elsevier, 2020.

Figure 7

FDM 3D printing apparatus with continuous fibers. Reproduced with permission from [63], Elsevier, 2016.

Figure 8

Depiction of fibers in FDM 3D-printed material and the different defects that occur with stress including fiber pull-out, filament delamination, debonding, and fiber breakage. Reproduced with permission from [49], Wiley, 2020.

Figure 9

Integration of graphene nanoparticles into FDM 3D-printed PLA. (a) Neat PLA after FDM 3D printing. (b) PLA/graphene nanocomposite after FDM 3D printing. (c) PLA and (d) PLA/graphene fractured cross-sectional microstructure. Reproduced with permission from [82], Wiley, 2018.