Page 281 - IJB-9-4

International Journal of Bioprinting 3D printing of continuous fiber reinforced PLA/PGA composites

like polyether ether ketone (PEEK) [9,10] due to their (CCF-PLA), and SCF/CCF-PLA specimens using FDM.
excellent mechanical properties and biocompatibility. The tensile and flexural properties of specimens were
However, metal materials have mismatching elastic experimentally investigated, and the results showed that
modulus with human bone, and PEEK material shows CCF-PLA had the highest tensile and flexural strength
inherent bioinert property and hydrophobicity . More of 245.40 MPa and 168.88 MPa, respectively, and the
[11]
importantly, these materials are non-biodegradable, specimen’s strength increased by 460% (tensile strength)
which limits their clinical application in degradable load- and 103% (flexural strength) compared to pure PLA.
bearing implant applications . Polylactic acid (PLA), a Due to the line-by-line bonding and layer-by-layer
[12]
biodegradable polymer, has been used to form non-load- stacking fabrication principle of the FDM process, the
bearing orthopedic implants (such as degradable bone mechanical properties of CCF-PLLA parts show obvious
plates and screws) and tissue engineering scaffolds due anisotropy, with the strength along the fiber direction far
to their admirable attributes in terms of biocompatibility, larger than those along the transverse direction and layer
biodegradability, and biosafety [13-15] . However, the direction [34,35] .
applications of PLA in load-bearing implant have
been restricted due to its poor mechanical properties. For biodegradable load-bearing bone implant
application, both the matrix and the reinforcement should
Adding the particle, short fiber, and continuous fiber
into the PLA matrix to prepare composite parts through be degradable materials. Conventional carbon fiber, glass
fiber, and kevlar fiber are non-degradable materials, which
the fused deposition modeling (FDM), 3D printing process cannot be used in biodegradable implants. Polyglycolic
is an effective way to improve the mechanical properties acid (PGA) suture is a kind of biodegradable continuous
of pure PLA parts [16-18] . Bioactive particles such as fiber, which can be used as an ideal reinforcement for
hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) biodegradable composite parts . Takayama et al.
[36]
[37]
have been added to the PLA to enhance the mechanical fabricated short PGA fiber-reinforced PLA composites
properties and bioactivity of the printed parts [19,20] . specimen by melt-mixing process, and a three-point
Aihemaiti et al. fabricated HA-PLA composite bone bending test was used to estimate flexural strength and
[21]
plates and investigated the effect of printing parameters modulus. Ko et al. introduced PGA fibers and HA
[38]
on the mechanical properties. Zhang et al. and Wang as fillers to PLA composite by using the manual fiber
[22]
et al. prepared polylactic acid/nano hydroxyapatite alignment and solution mixture solidification method.
[23]
(PLA/nHA) composite scaffolds with different loading These studies suggest that the PGA fiber greatly improved
of nHA by FDM, and the effect of the nHA ratio on the the mechanical properties of neat PLA, but the fabrication
mechanical properties of the scaffolds were studied. process was complex. Hedayati et al. used biodegradable
[39]
However, these study results showed that the addition of PGA suture as a continuous reinforcing fiber to enhance
HA particles has a limited effect on the improvement of the mechanical properties of the poly (ε-caprolactone)
mechanical properties. Even more, the high content of HA (PCL) by an in situ impregnation FDM method. The tensile
particles decreased the part’s strength because the particles strength and elastic modulus of printed parts remarkably
could easily aggregate and bubbles were introduced in increased. But the effect of printing parameters on the
the filaments. Therefore, the particle-reinforced PLA scaffold’s mechanical properties has not been studied.
composite parts cannot meet the mechanical property For the FDM process of continuous fiber-reinforced
requirement of the load-bearing implant. In addition, composites, many process parameters affect the mechanical
using short or continuous carbon fibers [24,25] , glass properties of the printed parts [40,41] .
fibers [26,27] , flax fibers [28,29] , and kevlar fibers to reinforce
[30]
PLA parts through the FDM process has been developed Our long-term research goal is to fabricate
as an efficient way of enhancing mechanical properties biodegradable load-bearing bone implants with tunable
of parts. Among them, the mechanical properties of mechanical properties through the FDM process. In this
the FDM-printed short fiber-reinforced PLA parts were study, PLA/PGA composite parts were fabricated by the
highly dependent on the fiber length and fiber content. FDM process with PGA suture as reinforcement phase
However, large fiber length and high fiber content may and PLA wire as matrix material. The process parameters
cause nozzle clogging ; in this manner, the enhancement including layer thickness, printing space, printing speed,
[16]
of mechanical properties of short fiber-reinforced parts is and filament feeding speed were investigated to analyze
limited. Continuous fiber reinforcement was an effective their impact on the mechanical properties of the printed
way to increase the strength of parts [31,32] . Maqsood et al. specimens. The results showed that the tunable mechanical
[33]
fabricated pure PLA, short carbon fiber-reinforced PLA properties range was obtained by altering the printing
(SCF-PLA), continuous carbon fiber-reinforced PLA parameters.

Volume 9 Issue 4 (2023) 273 https://doi.org/10.18063/ijb.734