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

in advanced engineering applications. The harvesting 3. NFRCF fabrication
and processing of natural fibers is notably less intensive
than other conventional materials such as concrete and Unlike other materials, natural fibers that are derived from
metals. The energy requirement to process the material organic sources tend to exhibit significant variability as a
is subsequently lower, which translates into a relatively result of maturity, environment, and harvest period, among
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lower processing cost for natural fibers. As a result, the other factors. Thus, specific considerations are needed
when processing and when transforming natural fibers into
use of natural fibers in the development of biodegradable alternative forms to ensure consistency during production.
composites in the production phase was advanced to In their raw and unmodified state, natural fibers have a
lead to reduced embedded energy in the developed tendency to absorb moisture content while displaying overall
products. 54
lower mechanical and durability attributes. 50,60,61 Besides
Besides their mechanical and physical attributes, some their limited physical and mechanical characteristics,
of the outstanding features of natural fibers that render natural fibers have a relatively low thermal stability which is
them attractive for AM are their sustainability attributes. below 200°C. Therefore, specific treatment modifications
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Given the potential of AM in numerous engineering are normally required in the pre-processing stage to prepare
applications, it is imperative to optimize the process for natural fibers, while care must be taken to ensure that the
improved efficiency and attainment of sustainability effects of thermal treatment do not lead to permanent
attributes. One approach is to consider alternative input alteration to their structure. Moreover, the lack of relevant
materials from greener or recycled sources at the expense standards regarding the fabrication and validation of
of conventional ones. Besides, the use of greener or 3D-printed materials and structures, respectively, adds to
recycled input materials will address the growing ecological the list of challenges observed in the emerging field of AM. 62
concerns as the promotion of renewable resources has The fabrication of filament materials from natural
a minimized environmental impact. In addition, such fibers for use in the FDM technique has been successfully
resources will possess a notably lower carbon footprint realized as reported in previous studies. 63,64 In one study,
given their reduced embodied energy, hence addressing NFRC components were successfully produced via the
the issue of climate change. 50
FDM technique by considering two types of natural
Product developers and manufacturers are looking at fibers involving hemp and New Zealand flax, which were
the entire lifecycle of products, including their disposal and impregnated in a polymeric matrix composed of lignin.
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recyclability, to address the growing issue of waste disposal Before the filament fabrication stage, the natural fibers
around the world. The disposability of modern developed were subjected to an alkali treatment consisting of NaOH
materials, which can have a reduced impact on the solution followed by a digestion cycle of around 30 min at
environment, is therefore regarded as a key requirement to 160°C. Finally, the fibers were thoroughly washed with tap
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attain sustainability. The conventional composite filaments water, subjected to drying in an oven for 48 h above 100°C,
used in the present-day AM process, which are mainly and mixed in an intensive mixer consisting of two rotating
composed of non-biodegradable components, add to the shafts and a heated chamber set at 185°C. A polylactic
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challenge of recycling. The consideration of natural fibers acid (PLA) binder in the form of power was used in the
for NFRCF development can address some of the foregoing mixing stage. The mixed composite material was then
issues encountered in the use of conventional filaments in subjected to a granulation stage followed by an extrusion
the AM process. process, which would produce continuous filament wire. 63
The shift toward greener materials such as NFRCFs One of the key parameters to control filament production
also aims to address the significant surge in the usage of is the cross-section of the filament wire. To achieve a
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non-biodegradable composites such as synthetic plastics. filament cross-section of acceptable tolerance, the electric
Their extensive usage has resulted in the accumulation spooling machine could be utilized to precisely control the
of non-degradable material in delicate environments extrusion and rotational speed of the filament spooling
such as in the ocean, thereby greatly affecting the Earth’s machine. The detailed outline of the filament fabrication
ecosystem. 55-59 Further research involving natural fiber- process is given in Figure 6. The filament extrusion stage,
based composites aims to look at alternative measures that which precedes the spooling stage, as displayed in Figure 6,
can enhance the degradability of conventional composites, is another decisive stage in the process of achieving
thereby minimizing the impact of waste disposal on the a filament end-product with consistent mechanical
environment. The use of natural fibers in NFRCF, which, properties and diameter. Even though both twin-screw
however, poses numerous challenges from fabrication to the extruders and single-screw extruder are widely considered
end of the lifecycle stage, is further examined in this review. for the filament extrusion process, the former was found

Volume 4 Issue 1 (2025) 6 doi: 10.36922/msam.8533