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Optimizing FDM Bronze PLA Composites Prints

Researchers from Iran and the UK are taking on central topics in digital fabrication, delving deeper into parameters, properties, and composites, with their findings outlined in the recently published ‘The Synergic Effects of FDM 3D Printing Parameters on Mechanical Behaviors of Bronze Poly Lactic Acid Composites.’

The authors use optimization in this study to find out more about the effects of printing on a bronze PLA composite. Popular due to its plant-based origins and biodegradable and biocompatible properties, PLA is a thermoplastic aliphatic polyester often made from corn starch. Fused deposition modeling is a popular method of 3D printing used with PLA and a variety of composites today—from bioinspired materials to graphene oxide, silver nano-wire photopolymers, and more. In this study, the authors investigate the use of bronze polylactic acid (Br‐PLA).

Schematic of 3D printing by the fused deposition modeling

The researchers worked to refine the mechanical properties of FDM-printed parts not only through experimenting with different input parameters but also by employing the design of experiment (DOE) method. Ultimately, the goal was to:

Print tough Br‐PLA samples
Reduce part thickness
Shorten build time

The following parameters were studied:

Layer thickness
Infill percentage
Extruder temperature
Maximum failure load
Thickness
Build time of parts

Levels of independent variables.

Design matrix and experiments results

Samples were designed using Simplify3D, and fabricated using Br‐PLA filament with a Sizan 3D printer. On testing the samples, the researchers noted that 80 percent of the results within the ‘design matrix’ displayed brittle fracture—and not surprisingly, as PLA is known to take on brittle properties during tensile loading.

“The fracture of brittle samples occurred at the elastic limit, while tough specimens showed the ability to undergo a low degree of plastic deformation before fracture,” said the researchers. “Therefore, samples with higher maximum failure load and elongation at the break had a tough fracture. However, a sudden brittle fracture is usually observed in samples at the elastic limit and in a lower failure load.”

(a) Brittle fracture of the specimen (sample #12 Br‐PLA), (b) Brittle fracture of the optimum PLA specimen, (c) fracture of #1 to #6 samples.

Extension‐force diagrams of (a) sample #2 and (b) sample #4

Using the DOE method to better the quality of their experiments and cut down on testing, the team measured 20 of the samples for maximum failure load, thickness, and build time.

Analysis of variance (ANOVA).

3D surface plot of the build time with (a) infill percentage and layer thickness; (b) extruder temperature and layer thickness; (c) infill percentage and extruder temperature.

Overall, the researchers noted that their optimization technique was successful. ‘Predicted optimum results and experimental validation’ varied little, with few errors. In comparing PLA and Br‐PLA 3D printed samples, PLA clearly showed higher tensile strength. This was attributed to use of greater infill percentage—as well as the fact that PLA is intrinsically stronger because it is a single material—in comparison to the composite made up of two materials.

Overlay plot of 3D printing optimization with (a) infill percentage and extruder
temperature; (b) extruder temperature and layer thickness.

Extension‐force diagram of the specimen for solution 3

The optimized Br‐PLA samples successfully resisted over 1000 N, with the following parameters:

Layer thickness of 0.25 mm
Infill percentage of 15.20
Extruder temperature of 222.82 °C

“For producing a suitable sample with good mechanical and economical features, middle extruder temperatures and low infill percentages must be considered. Because in the Br‐PLA 3D samples, the heavy and rough samples might not be used very much, and the heavier samples are costly,” concluded the researchers.

“In the PLA 3D printing samples, the maximum failure load was reported more than Br‐PLA samples, and that is because the composite structure has the more particle’s space, and in Br‐PLA, the metal component takes up more space than PLA structure.”

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[Source / Images: ‘The Synergic Effects of FDM 3D Printing Parameters on Mechanical Behaviors of Bronze Poly Lactic Acid Composites’]

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Thailand: Comparing Suitable Fillers for Making PLA Composites

Researchers from King Mongkut’s University of Technology Thonburi in Bangkok, Thailand continue to study the science of materials in 3D printing—a topic that has continued to expand throughout recent years especially as the technology has infiltrated the mainstream and been widely embraced not only just in labs but also a wide range of industries, educational systems, and both offices and homes too on the individual level. Their current research is outlined in the recently published ‘Comparison of Filler Types in Polyactic Acid Composites for 3D Printing Applications.’

Through customization of materials, users today can look forward to greater freedom to innovate in their own work, whether designing prototypes, parts, medical devices, DIY projects in the home, and more. PLA is widely used (along with other standards like ABS) due to its accessibility, affordability, and biodegradable nature as a plant-based material. In this study, the researchers examined a variety of fillers suitable for PLA, assessing which additives would be best for preventing brittleness in parts.

Filler types evaluated in this study included:

Wood flour (WF)
Talc (TC)
Calcium carbonate (CaCO3)
Microballoon (MB)
Silicon dioxide (SiO2)

Samples were designed in SolidWorks 2014, and then files were imported into Cura 2.6.2. The researchers used FDM 3D printing to manufacture objects for tensile testing.

Settings in Cura 2.6.2

Sample of 3D Printed Tensile Specimen

Dumb-bell shaped samples were tested for Young’s modulus, tensile strength, and elongation at break.

“It was found that the 3D printed parts were completely fabricated and stable in shape during fabrication,” stated the authors in their research paper. “The 3D printed composites were a difference in color and texture which were dependent on the color and physical of fillers. The PLA/TC, PLA/CaCO3, PLA/MB and PLA/SiO2 composites were a whitish, and smooth surface while the PLA/WF composites were brown and rougher surface.”

Tensile Properties of 3DPrinted Composites

The 3Dprinted parts of PLA composites:(a) neat PLA,(b) PLA/WF, (c) PLA/TC, (d) PLA/CaCO3, (e) PLA/MB, and (f) PLA/SiO2

Through adding TC and MB, the researchers were able to decrease brittleness. With the PLA/TC composites, greater elongation and flexural strength were displayed in contrast to neat PLA and other composites.

“The 3D printed PLA/TC composites had greater elongation and flexural strength compared to neat PLA and PLA composites because of the plated of talc that would be terminated the cracks and then it supported the further force. The PLA filled with glass microballoons gave the best impact strength, the reasons being associated with the highest melt flow rate that led to a great fusion and bonding between layers. Moreover, the TC-filled and MBfilled PLA composites were stable in shape during fabrication that was satisfied both in the manufacturing and the tough properties,” concluded the researchers.

“For the thermal properties, the PLA slightly deteriorated Vicat softening point when adding the fillers, except for PLA/MB. Next, we focused on the investigate the properties of PLA filled with glass microballoons for 3D printing application in the tooling holder for CNC machine. Next, we focused on investigating the friction and wear properties of 3D printed parts of PLA filled with glass microballoons for making the tool holder in the milling CNC machine.”

If you are a 3D printing user today you have access to an overwhelming number of different types of software, hardware, and materials. Composites are being studied widely, from silver-nanowire photopolymers to PLA antioxidants, to wood composites, and more.

What do you think of this news? Let us know your thoughts; join the discussion of this and other 3D printing topics at 3DPrintBoard.com.

SEM Micrographs of the Fractured Surface of Filament Composites: (a) neat PLA,(b) PLA/WF, (c) PLA/TC, (d) PLA/CaCO3, (e) PLA/MB, and (f) PLA/SiO2

[Source / Images: ‘Comparison of Filler Types in Polyactic Acid Composites for 3D Printing Applications’]

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Belfast: 3D Printing with Antioxidant PLA Composites Shows Potential in Medical Applications

In the recently published ‘Antioxidant PLA Composites Containing Lignin for 3D Printing Applications: A Potential Material for Healthcare Applications,’ Belfast researchers experiment with new 3D printing materials. Due to its strength as a biopolymer and an antioxidant, the research team combined lignin with poly(lactic acid) in FDM 3D printing.

Scheme of the different meshes produced using FFF.

Coating PLA pellets with LIG powder and castor oil, which is biocompatible, they extruded the material at 200 °C. The researchers reported LIG loadings that ranged from 0% to 3% (w/w). With the goal of providing additional, beneficial features to PLA, the research team tried varied strategies, to include incorporating molecules with antioxidant properties to PLA.

“The unrestrained production of free radicals and reactive oxygen species is linked with the onset of diseases such as rheumatoid arthritis, atherosclerosis or cancer,” stated the researchers. “Accordingly, the development of antioxidant compounds/materials can contribute to reduce the concentration of these compounds. Moreover, it has been shown that the excess of reactive oxygen species prevents wound healing. Accordingly, antioxidants have been proposed to control oxidative stress in wounds to accelerate their healing.

Photographs of: PLA and PLA coated pellets (A); LIG and TC containing PLA filaments (B); LIG and TC containing 1 cm × 1 cm squares prepared using 3D printing (C); and different shapes printed using the filament containing 2% (w/w) LIG (D).

Previously, SLA 3D printing was used to fabricate antioxidant vascular stents with bioresorbable abilities, while SLS 3D printing was used to create materials with antioxidants to promote cell growth. While the actual compound was not disclosed, the researchers reported that they used UV-stable polyamide 12 material with antioxidant properties. LIG is known to possess both antioxidants and antimicrobes and incidentally, is also the second most abundant polymer on our planet—with researchers still having plenty of studying to do—especially for biomedical applications.

As the researchers combined LIG with PLA here, the intent was to develop a composite for healthcare as the materials were combined through extrusion, characterized, and then actually used in FDM 3D printing. It is expected that these composites can be used for wound dressings due to the potential for localized antibacterial qualities. Here, the researchers used tetracycline (TC) as the antibacterial agent.

Used in wound dressings, the composite made up of LIG and PLA would allow for customization of size and shape—and not only that, PLA offers a biodegradable form.

“The present work showed that PLA and LIG can be combined easily by coating PLA pellets with LIG. Other alternatives to prepare PLA/LIG composites have been explored but they require organic solvents or more complex equipment such as twin screws extruders,” concluded the researchers.

“Antioxidant packaging can be used to improve the condition and increase the shelf-life of packaged food. Due to the enhanced cell proliferation on antioxidant materials, these materials can be used for tissue culture applications or even for regenerative medicine. Due to the versatility of FFF, complex geometries can be prepared such as scaffolds. However, before this type of material can be implanted into humans, the safety of lignin-based materials should be evaluated. It has been reported before that LIG-based materials are biocompatible, but more studies should be performed.”

Experimental setup used to measure drug diffusion trough the 3D printed meshes (A); photographs of the 3D printed meshes made of PLA and 2% (w/w) LIG (B); and CUR release through 1.5 mm (C) and 1 mm (D) 3D printed meshes (n = 3).

As the range of 3D printing materials continues to expand, so does research and development of composites, from thermoset composites for aerospace to glass composites, nanocomposites, and more.

What do you think of this news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com.

[Source / Images: ‘Antioxidant PLA Composites Containing Lignin for 3D Printing Applications: A Potential Material for Healthcare Applications’]

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Improved FDM 3D Printing with Lignin Biocomposites

In the recently published ‘Lignin: A Biopolymer from Forestry Biomass for Biocomposites and 3D Printing,’ international researchers Mihaela Tanase-Opedal, Eduardo Espinosa, Alejandro Rodríguez, and Gary Chinga-Carrasco explore a very specific area of materials related to biopolymers.

As composites are used more often these days to improve existing materials—especially in 3D printing—alternative materials like wood are being experimented with also. Fiber-based biocomposites and lignin can be better options than petrochemical-based products. For this study, the authors gleaned lignin from spruce trees being reduced to pulp. They used the material to create composite filaments, printing sample dogbones to test mechanical properties.

Natural-fiber biocomposites offer the following:

Affordability
Good mechanical properties
No emission of toxins
Light weight

PLA is a popular polymer used in 3D printing, and as the authors remind us, it is actually a biopolymer—featuring good mechanical properties, biodegradability, easy melt-processability, and much more; however, it is also not always cost-effective or suitable for every project. As a composite, however, PLA becomes more versatile.

“Each year, over 50 million tons of lignin are produced worldwide as a side product from biorefineries, of which 98% are burned to generate energy. Only 2% of the lignin has been used for other purposes, mainly in applications such as dispersants, adhesives, and fillers,” state the researchers.

“Without modification, lignin can be directly incorporated into a polymeric matrix, such as UV-light stabilizer, antioxidant, flame retardant, plasticizer, and flow enhancer to reduce production cost, reduce plastic, and potentially improve material properties.”

As 3D printing brings so many advantages forth to industrial users, with the ability to create affordable and complex structures, as well as leaving behind less waste and energy usage, materials like lignin are attractive for use when mixed with other polymers. For this study, the researchers focused on PLA/soda lignin biocomposite filament for 3D printing.

“A motivation for selecting soda lignin is that it is sulphur-free. Soda lignin was thus expected to reduce the typical smell that is experienced when melt-processing biocompounds containing kraft lignin or lignosulfonates,” stated the researchers.

Samples were assessed for:

Mechanical (tensile testing)
Thermal (TGA, DSC analysis)
Morphological (SEM)
X-ray diffraction
Antioxidant properties

An original Prusa i3 MK3S was used in FDM 3D printing of the dogbone samples, with a length of 63mm and width of 3mm. Three sets were printed, as well as a phone case. The biocomposite demonstrated an increase in mechanical properties when temperatures were increased, with elastic modulus decreasing by 25% to 32%. Lignin offered an improvement in ductility, but a decrease in plasticity.

Mechanical properties of PLA and PLA/Lignin biocomposites.

Stress−strain curves for the different biocomposites

Antioxidant properties were also confirmed, showing that 3D printed samples with lignin had even more antioxidant capability than PLA, meaning there is the potential for use for other applications such as food packaging.

“The suitability of the PLA/lignin biocomposite filament for 3D printing was also tested, by printing a smartphone protective case,” stated the researchers. “The printing process revealed a good performance of the lignin-containing filament, and a functional protective case was effectively 3D printed. PLA/Lignin filaments are a plausible option for lignin utilization with potential in, e.g., rapid prototyping and consumer products. It is worth to mention that the typical smell from some lignins was not detected during the extrusion of the filaments or during the printing process, which is an additional advantage of using soda lignin in PLA biomaterials.

“Biocomposites exhibited good extrudability and flowability with no observable agglomeration of the lignin. This suggests that lignin-containing biocomposites are plausible alternatives for 3D printing applications.”

3D printing of a smartphone protective case with PLA/lignin biocomposite filament

The use of composites today is a growing trend due to the ability to improve prototypes and parts, from glass composites to copper metal to particle reinforced nanocomposites. What do you think of this news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com.

[Source / Images – ‘Lignin: A Biopolymer from Forestry Biomass for Biocomposites and 3D Printing’]

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US Researchers Create 3D Printing Filament from Recycled Cellulose Polypropylene

In this recently published study, ‘Recycled Cellulose Polypropylene Composite Feedstocks for Material Extrusion Additive Manufacturing,’ researchers from the US explain their findings in using not only composites but those made out of recycled material. Here, the focus is on using polypropylene reinforced with cellulose waste to create 3D printing filament for material extrusion additive manufacturing (MEAM).

With cellulose being more commonly used to strengthen thermoplastics, today, such composites can be helpful in applications such as decking, paneling, furniture, household goods, and more. Not only are they plentiful, but also affordable to use—and best of all, renewable. Such materials also offer strength, low-bulk density—along with less abrasion, meaning that products last longer. To date, many studies have centered around ABS and PLA composites; in fact, some have even included using materials like ground-up macadamia shells with ABS.

For this study, materials like wastepaper, cardboard, and wood flour were used for additives, with powders melted into filament and then printed into samples for testing, considering that mechanical properties could be affected due to filler, along with wettability.

“Strong particle–matrix interfacial adhesion can improve toughness due to efficient stress transfer between phases,” stated the researchers. “On the other hand, poor wetting can lead to debonding, plastic void growth, and shear banding mechanisms, which absorb energy and can improve toughness.”

The composites were created through pulverization, minimizing particles for better results in fabricating samples. The ingredients used for the composite were rather interesting too, in the form of Wegmans and Great Value yogurt containers, along with office printer paper, corrugated cardboard, and wood flour.

“Recycled polypropylene from yogurt containers was cleaned by rinsing with water, ethanol and drying in the air at room temperature. The labels were removed before cutting into pieces that could be fed into the paper shredder (Compucessory model CCS60075). Wastepaper and cardboard were fed through an identical cross-paper shredder,” explained the researchers.

Recycled PP and cellulose starting materials, powder, and filament generated from SSSP. (A) Waste paper, (B) rPP/WP SSSP powder, (C) rPP/WP filament, (D) rPP shreds, (E) rPP/CB SSSP powder, (F) rPP/CB filament, (G) wood flour, (H) rPP/WF SSSP powder, (I) rPP/WF filament. WP = waste paper, CB = cardboard, WF = wood flour.

While all the samples were 3D printed as planned, the researchers pointed out that clogging was an issue for some pieces when using the typical 0.5 mm nozzle. The team theorized that cellulose was responsible for the clogging due to some particles not ground finely enough. Cardboard and paper did not always remain sufficiently mixed either. 3D printing was performed on a Lulzbot Taz 6 3D printer, with a 100 °C bed temperature and a 220 °C nozzle temperature used.

“Sections along the length of a filament spool were examined by scanning electron microscope and thermogravimetric,” concluded the researchers. “The rPP/CB composites have a greater loading of cellulose compared to the commercial PP (cPP)/CB composites, but loading does not change significantly along the ca. 30 ft. examined. Further, weight percent remaining by TGA does not show significant differences in char along each respective filament.”

Ultimate tensile strength (hatched bars) and modulus (solid bars) of printed PP with 10 wt % cellulose. *, **, # significantly different from the respective control. WP = waste paper, CB = cardboard, WF = wood flour.

While 3D printing today offers a host of different materials to choose from as a whole, many are better when reinforced, meaning that composites are becoming increasingly more popular from copper metal to continuous wire polymers or continuous carbon, and more—even to include alternatives like wood and cork.

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[Source / Images: [‘Recycled Cellulose Polypropylene Composite Feedstocks for Material Extrusion Additive Manufacturing’]

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