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Materials Science in Additive Manufacturing Natural composite filaments for 3D-Print

Clogging was commonly observed during the FDM process 4.2. Matrix for biodegradable NFRCFs
due to the presence of large-sized particles in the natural As reported in the foregoing literature review, the binding
fiber composite mix. Blockage in the extrusion process matrix material plays an important role in NFRCFs
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was reported to occur in filament material consisting of a fabrication as well as in the AM process. First, it is an
weight percentage of fibers from 20% and above. In line indispensable component used to consolidate filament
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with the above, the presence of a higher amount of fibers in strength by solidifying the latter into a homogenous
the filament material due to a non-homogeneous mixture mix, which incorporates key filament elements such as
was reported to lead to other printing issues besides reinforcement components and plasticizers. Second, to
blockage at the nozzle section. For instance, an increase ensure high-quality prints, the binding matrix material
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in the fiber content in the composite mix of the filaments provides numerous benefits that could affect the essential
would lead to an increase in their melt viscosity, thereby printing parameters in the FDM process, namely layer
raising their power requirement for extrusion. Moreover, adhesion, surface finish, shape stability, and smooth
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another barrier associated with the excessive increase in extrusion, among other factors. 49
the fiber content and a corresponding reduction in the
binding matrix material was reported to accentuate the PLA, which is widely recognized for its biodegradability,
brittleness nature of the produced filaments. Figure 8 is the most commonly used polymeric matrix material in
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displays the schematic outline of the filament extrusion the production of NFRCFs. 49,86 PLA was also found to be
process based on varying fiber content and varying fiber the principal choice for binding matrix material, as was the
specifications. 94 case observed in hybrid composites composed of purely
The full potential of natural fibers in filament material, natural fibers. 73,98 Besides being biodegradable, PLA was
namely their renowned tensile strength along their found to display notable tensile strength despite exhibiting
length, has not been fully exploited due to manufacturing poor heat resistance. It is to be noted that the mechanical
restrictions. In one study involving composite-based and heat resistance performances of PLA materials have
biofilaments, a trial was made by integrating continuous been reported to depend on the crystallization temperature.
flax fibers into a PLA matrix. The prefabricated At higher crystallization temperatures, imperfections
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continuous flax yarns, which had a linear density of 68 in the form of irregular crystal formation were found
Tex, yielded enhanced mechanical performance in terms to contribute to a deterioration in the mechanical
of increased tensile modulus and strength values. On performance of the PLA material.
the downside, however, the transverse strength of the In recent years, more attempts have been made to
developed filament material was found to be inferior realize fully biodegradable composite-based biofilaments.
in comparison to similar flax-PLA thermocompressed Both the natural fiber reinforcement and biodegradable
composites. Part of the weaknesses observed in the matrix components are combined to produce sturdy
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mechanical behavior of such filament material was filament wires for 3D printing. Table 4 summarizes some
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attributed to poor dispersion and imperfect impregnation of the notable progress made in the development of fully
of flax yarns within the PLA matrix as a result of the fiber biodegradable composite-based biofilaments for the FDM
bundle organization. 95 process. The table includes the specification, composition,

Besides fiber-related factors such as fiber treatment, characteristics, and applications of the various researched
composite preparation, and inclusion of compatibilizer biofilaments composed of natural fibers integrated into a
agents, which can exert diverse influence on the FDM- biodegradable matrix.
based 3D printing process, the quality of the final 3D 4.3. Fiber-matrix interaction and their
print largely depends on the printing parameters. Some corresponding properties
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of the main printing parameters which are associated
with the quality of natural fiber-reinforced polymer The reported physical and mechanical properties of
composites in FDM-based 3D printing are the printing FDM filaments are diverse, and these variations have
temperature, layer height, and infill percentage, among been linked to the material source involving the fiber and
others. Besides the quality aspect, the mechanical matrix components. One notable factor that normally
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properties of 3D-printed products in general have been contributes to the inferior performance of natural
reported to be affected by the layering technique, which fibers when integrated with NFRCFs is their poor fiber-
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also tends to result in a highly anisotropic material matrix adhesion. As reported in past literature studies,
behavior, 96,97 as shown in Figure 9. In addition, layer- mechanical test evaluations were conducted to shed light
by-layer printing often leads to void formation that also on the mechanical performance of NFRCFs. Given the
affects the structural soundness. 73 extensive use of PLA in NFRCFs, most of the reported

Volume 4 Issue 1 (2025) 10 doi: 10.36922/msam.8533