Sustainable 3D Printing Filaments: an In-Depth Comparison

Introduction

3D Printing is an additive manufacturing technique that is used for precise prototyping and production of small-scale products. There are many types of 3D printing techniques, but the most common are material jetting, material extrusion, and powder bed/vat fusion [1]. Material jetting is a type of additive manufacturing that sprays material through a nozzle onto a bed plate in microscopic droplets that fuse together to form a uniform object. This process can generate highly detailed and precise models, but is quite expensive and is not generally available to the public. Powder bed/vat fusion is another additive manufacturing technique that is not generally available to the public. It works by directing a high energy laser light at a bed made of powder or a vat of special liquid resin to heat the material quickly and precisely. The powder/liquid solidifies under the laser light, layer by layer, to create a uniform object. Although these techniques are interesting and complex, they are not widely used among the general public. The most common 3D printing technique is material extrusion [1].

Material extrusion is when thermoplastic material, called filament, is pushed through a heated nozzle and deposited onto a heated bed in layers to create a 3D object. Thermoplastic filaments are malleable when heated to high temperatures and can be used to form objects that solidify when cooled. Different types of filaments have different mechanical properties, melting points, and shrinkage rates. Depending on the application, different filaments can be used to achieve the desired aesthetic and mechanical qualities for the product.

3D printing is a quickly emerging technology with many applications in medical sciences, manufacturing, and art, but it comes with challenges. Many thermoplastics are not recyclable and are unsustainably sourced, affecting climate change, waste solutions, and aiding in the advancement of environmental decline. Almost every type of 3D printing filament is classified as Type 7, or “Other”, which cannot be processed by municipal recycling facilities under the ASTM International Resin Identifier Codes [2]. However, increased research into bio-plastics and alternative sustainable thermoplastic solutions proves that similar, more sustainable filaments, can be created with the same mechanical properties, sustainable material sourcing, and increased recycling abilities, thus aligning with the UN Sustainable Development Goals of “Responsible consumption and production” and “Industry, innovation, and infrastructure” [3]. By utilizing more sustainable filaments, manufacturers can reduce carbon emissions and support a circular economy. This research paper focuses on the sustainability, printability, and durability of various commercially available material extrusion filaments.

Research

Evaluating filaments based on sustainability was achieved through completing a low-level life cycle analysis—a standardized methodology used to evaluate the environmental impacts of a product, process, or service, across its life cycle. By observing the effects of the filament production, use, and disposal using the triple bottom line evaluation metrics (people, planet, profit), the sustainability of the filaments is compared. The table below compares a variety of commercially available filaments based on the triple bottom line.

Table 1: Triple Bottom Line

Filament Type	People	Planet	Profit	kg CO2 eq.
ABS (Acrylonitrile Butadiene Styrene)	– Emits toxic gases while printing   – Cannot be recycled in household recycling bins: consumers must make an effort to recycle [4]  – Chemical exposure during manufacturing can pose health hazards [4]	– High durability results in less remanufacturing and replacement of parts [4]  – 3D printing technologies for ABS are becoming more efficient [4]  – Production relies heavily on petrochemicals, derived from fossil fuels [4] – Not biodegradable [4]	– High manufacturing efficiency [4]  – Expensive due to high energy consumption and materials [4]   – Seeing an increased use in renewable energy applications [4]	3.1 kg CO2 eq. [10]
PLA (Polylactic Acid)	– Most common filament type: easy to use and cheap [1] – Cannot be used for food packaging due to potential PFAS cross contamination [5] – Decreased land use for food crops	– Biodegradable: made from renewable resources (corn syrup/glycerine) [6] -Bio-degradability depends heavily on specific environmental conditions [5]   – Composting process	– Cheap and widely available  – Can be recycled: requires special processes and facilities  – 3D printing results in reduced waste product	3.3-3.7 kg CO2 eq. (depending on end-of-life) [5]
rPLA (Recycled Polylactic Acid)	– Cannot be recycled in household recycling – Increased land use for food crops	– Utilizing recycled plastic: reduces cost and embodied energy by 90% [7] – Reduced environmental effects of growing crops for virgin PLA [7]	– Shift to recycled filaments affects stakeholder decisions [7]  – Use of recycled/waste materials supports circular economy  manufacturers reduce overall waste	2.55 kg CO2 eq. [11]
Algae-Based PLA	– Not home-compostable [8]	– Increased harvesting of invasive algae species leads to increased well-being of surrounding ecosystems [8]  – Algae grown has high CO2 absorption capacity and non-competing with food resources [8] – Algae has good PLA adhesion, increasing biodegradability [1]	– Currently being researched for biomedical applications [1]  – Currently being used for sustainable 3D printing applications [1]	Research on a full LCA is currently in development. [8]

Although evaluating the triple bottom line can be useful in observing the effects of the life-cycles of these filaments on the environment, it is also important to consider material sourcing, production, and end-of-life when considering the entire sustainability of these filaments.

Life-Cycle of ABS:

ABS is made from thermoplastics that are derived from petroleum-based resources, making it a non-renewable material. It is also flammable and emits a toxic gas when it is heated or melted, so precautions must be taken when printing and storing material [4]. ABS is manufactured by polymerizing styrene and acrylonitrile in the presence of polybutadiene [4]. This process results in high carbon emissions from production facilities as well as air and water pollutants from washing and drying the filament. Recent technological developments are increasing the efficiency of this process; however, it is still considered a fairly high emission stage of the life cycle of ABS. The manufacture of ABS can pose health hazards for workers due to exposure to harsh chemicals. ABS cannot be recycled in typical household recycling municipalities and requires specialized recycling techniques that not all municipalities offer, increasing the energy consumption and emissions at the end-of-life. ABS is also not biodegradable, making it difficult for users to dispose of the plastic safely and sustainably [4].

Life-Cycle of PLA:

Virgin PLA is made from materials derived from corn and sugarcane [6]. It is produced by fermentation of crops with high sugar content such as corn, potato, sugarcane, and beet which produce lactic acid, then lactide, and finally polylactic acid [1]. Although raw materials are considered renewable, it is not sustainable because growing crops for the production of PLA uses land that would otherwise be used for growing food crops. The increase in virgin PLA production can contribute to the increased food insecurity across the globe. PLA is more easily and widely recycled than ABS, and can be remanufactured to create rPLA (recycled PLA) or incorporated into other recycled products. PLA is also considered biodegradable; however, it requires very specific environmental conditions for the chemical bonds to break down. PLA cannot biodegrade in a landfill setting, let alone a backyard compost bin, making it difficult for consumers to dispose of smartly.

Life-Cycle of rPLA:

Recycled PLA is made from recycled filament, manufacturer waste, or other recycled plastic products. The use of recycled materials decreases the reliance on crop growth for virgin material, and decreases the burden on landfills and other disposal municipalities. Recycled PLA can decrease manufacturing energy and costs by minimizing energy-intensive processes involved in production of virgin PLA, and it requires only half of the energy consumed to produce new feedstock from virgin materials [7]. rPLA can be recycled and remanufactured many times. It is considered biodegradable, but like virgin PLA, it has a low degradation rate with a lifetime of 3-5 years [7].

Life-Cycle of Algae-Based PLA:

The types of algae and seaweeds being used for research and development of this PLA originate from Scandinavian countries, where they are considered an invasive species. Thai specific species turns into coral when they die, which greatly impacts marine life. By harvesting these plants, the health of the local ecosystem improves greatly, and the plants can be used to develop new technologies for 3D printing [8]. Unlike traditional PLA, the utilization of algae does not pose a threat to food supply because it does not require farm-land to harvest materials like other bioplastics made from starches or food crops [1]. Commercially available algae-based PLA is made from 50% post industrial recycled (PIR) PLA content recovered from controlled manufacturing waste streams and blends premium PLA with 5-10% algae bio-filler [8]. The inclusion of algae in the filament makes it more biodegradable due to increased adhesion to PLA polymer mix, and algae’s high nitrogen content.

Test Plan: Durability & Printing Performance of Various 3D Printing Filaments

Purpose:

Evaluating mechanical properties of filaments can reveal a lot about the durability of unconventional materials and can help an engineer choose which material type would best suit their product design. Typical virgin plastic filaments have consistent mechanical properties, but recycled filaments and infused filaments typically have slightly different mechanical properties due to extra processes endured during production. The purpose of this experiment is to compare mechanical properties and printing performance of virgin plastic 3D printing filaments and other sustainable alternatives.

These filaments were evaluated based on their printability and durability. The printability of a filament was determined through qualitative data collection based on ease of use, printing performance, and the quality of the finished print. To maintain consistency, all test prints were printed using the same 3D printer.

Durability was evaluated using the Young’s Modulus of Elasticity for each filament type. The Young’s Modulus is a measure of material stiffness, defined as the ratio of tensile or compressive stress to the corresponding strain in the elastic region. Tensile testing gave information on the stress and strain each filament type endured, and the Young’s modulus was calculated using those values. A higher modulus relates to a higher tensile strength and vice versa.

Equipment Used:

• Tensile tester
• 3D Printer: Creality Ender-5 Max – Filament
• Generic ABS
• Generic PLA
• Protopasta – Recycled PLA

• Filamentive – Algae-Based PLA

Experimental Setup:

For this procedure, filaments were tested on a tensile tester to gather information about longitudinal, or tensile, stress and strain. The test strips were dogbone shaped to ensure breakage did not occur at the gripping ends, and the thickness of the test strips were 4.8mm due to the limitations of the tensile tester. Figure 1 shows the CAD drawing of the test part created in Onshape.

Figure 1: CAD render of dogbone test print

The dogbone shape was printed both vertically and horizontally, with 100% infill for all four filament types resulting in eight total test pieces. Printing horizontally resulted in layer lines that ran parallel to the length of the dogbone, while printing vertically resulted in layer lines that ran perpendicular to the length of the dogbone. Each orientation expected different stress and strain results due to layer adhesion—the strength of the bond between successive layers in a 3D printed part. Figure 2 shows the difference in layer orientation between the horizontal and vertical prints.

Figure 2: Different layer orientations

For tensile testing, each test print was placed vertically in the tensile test machine and stretched  at a rate of 10mm/min. Figure 3 shows an example of the experimental setup for the tensile tester.

Figure 3: Generic PLA in tensile tester  Results:

All filaments were printed on the same printer, using different temperature settings, and each filament performed very differently.

The Generic ABS required extensive test prints to get the temperature settings correct. One of the main issues was getting the filament to stick to the printbed and keeping ventilation on the area to avoid chemical offgas. The final printed part was not very clean, and the support structures caused some inconsistencies in the surface of the print. The ABS dogbone shapes were noticeably lighter in weight compared to all other filaments.

The Generic PLA was the easiest to work with. Printing temperatures provided by the manufacturer worked well, and it printed very smoothly. The surface finish was the smoothest of all other printed filaments.

The recycled PLA was also very easy to work with. Printing temperatures provided on the Protopasta website worked well, and it printed very smoothly. The surface finish was relatively smooth, and the filament itself contained some specks of glitter, making the final print a bit sparkly.

The Algae-reinforced PLA was the worst filament to work with. There were no recommended temperature settings posted on the Filamentive website for this filament, so many test prints were made to figure out which worked the best. Because the filament is made from many different materials, it contained inconsistencies and inclusions that often clogged the nozzle of the printer. Due to consistent clogging, the filament was printed using a 0.6mm nozzle rather than the typical 0.4mm nozzle. The texture of the filament was also very different from generic PLA. It was more matte in finish and it had a rougher texture. The finish of the printed part was smooth but a little stringy.

Table 2 shows the printing temperatures that were used to successfully print each part with the two temperatures for the algae-PLA corresponding to the vertical and horizontal printing orientations.

Table 2: Test Print Settings

Filament Type	Bed Temp. (°C)	Nozzle Temp. (°C)
Generic ABS	110	240
Generic PLA	85	220
Protopasta rPLA	55	220
Filamentive Algae-PLA	55 / 80	217 / 195

Figure 4 shows the printing process of the Algae-PLA on the Creality Ender 5-Max.

Figure 4: Algae-PLA printing process

Once all eight dogbone shapes were successfully printed, tensile testing was performed. The width and thickness (in mm) were input into the testing software which measured the tensile stress, strain, percent elongation at the break, the Young’s Modulus, and the peak load applied to the sample. The raw experimental data outputted by the testing software can be found in Appendix 1. Table 3 is a summary of the collected data for the dogbone shapes with layers parallel to the length of the dogbone.

Table 3: Tensile Test Data Collection and Calculated Values Parallel Layers

Filament Type	Cross-sect ion width (mm)	Cross-secti on length (mm)	Peak Load (N)	Peak Stress (MPa)	Young’s Modulus (MPa)	Strain at Break (%)
2. ABS	4.60	30.08	2648.043	19.1	883.991	3.255
4. PLA	5.15	30.17	4934.934	32.3	1093.462	4.063
3. rPLA	4.90	30.09	4704.278	31.9	1125.224	3.644
1. Algae-PLA	4.51	30.04	4919.970	36.3	1376.696	3.985

Figure 5 shows the broken Algae-PLA dogbone part with parallel layer lines after it was stretched on the tensile tester.

Figure 5: Algae-PLA parallel layer lines after tensile test

Table 4 summarizes the results of the collected data for the dogbone samples with layer lines perpendicular to the length of the dogbone.

Table 4: Tensile Test Data Collection and Calculated Values Perpendicular Layers

Filament Type	Cross-sect ion width (mm)	Cross-secti on length (mm)	Peak Load (N)	Peak Stress (MPa)	Young’s Modulus (MPa)	Strain at Break (%)
5. ABS	4.81	30.14	1231.990	9.6	834.940	1.410
6. PLA	4.88	30.17	1164.847	7.9	834.940	1.410
7. rPLA	4.97	30.21	2523.967	16.9	1099.636	2.100
8. Algae-PLA	4.72	29.92	556.454	3.9	594.100	2.135

Figure 6 shows the generic PLA sample with perpendicular layer lines after it was stretched on the tensile tester.

Figure 6: Generic PLA after tensile test

The samples that had parallel layer lines had inconsistent fracture points that were rugged and seemingly random. Figure 7 shows the broken parts for all samples with parallel layer lines.

Figure 7: Parallel layer lines broken samples; left to right: PLA, rPLA, ABS, Algae-PLA

Most of the sample with perpendicular layer lines broke along one of the layers in a straight, clean line. The recycled PLA did not break cleanly across one layer, but instead, broke across two layer lines which can be attributed to the high layer adhesion strength. Figure 8 shows the broken parts for all samples with perpendicular layer lines.

Figure 8: perpendicular layer lines broken samples; left to right: Algae-PLA, rPLA, PLA, ABS  The testing software used for the tensile tester continuously collects data throughout the test and generates a graph of stress (ksi) and percent strain (%) for each sample. Figure 9 shows these graphs superimposed together. A key is included below to indicate the testing order of the samples.

Figure 9: Graphical tensile testing data  Parallel Layer Lines: 1. Algae-PLA

2. Generic ABS
3. Recycled PLA
4. Generica PLA

Perpendicular Layer Lines:

5. Generic ABS
6. Generic PLA
7. Recycled PLA
8. Algae-PLA

Date test conducted: 10/03/2025

Conclusion:

Upon evaluation of the tensile testing results, it can be concluded that the tensile strength of the Algae-PLA was greater than other tests for parallel layers with a value of 1376.696 MPa. This means that it would be the strongest in applications where stress would be applied longitudinal to the layer lines. However, the layer adhesion for the Algae-PLA was the lowest compared to other filaments with a value of 594.100 MPa. This can be determined from the horizontal layer tensile test.

The 100% recycled PLA had the best layer adhesion seen by the very large Young’s Modulus result for the perpendicular layer tensile test with a value of 1099.636 MPa. It can be seen in Figure 8 that the recycled PLA fractured across multiple different layer lines while the other filaments fractured cleanly across only one layer line. The recycled PLA also performed very well during the parallel layer lines tensile test ranking second in strength with a Young’s Modulus value of 1125.224 MPa.

The generic ABS and generic PLA performed as expected, and the results were comparable to values posted online by various manufacturers. Based on the tensile test results, the prior research, and the printing process, the recycled PLA is the best commercially available filament to use for small-scale projects. It was simple to use, had predictable temperature settings, printed very easily, and was relatively strong in both parallel and perpendicular directions. In addition, the recycled PLA promotes a circular economy through remanufacturing both post-consumer recycled material and postindustrial recycled material. It was also one of the easiest materials to obtain. The generic ABS, generic PLA, and recycled PLA are simple to order and are predictable in terms of price and quality. However, the Algae-PLA was extremely expensive due to the high tariffs the US imposes on international goods. The algae-PLA was manufactured and shipped from Jamaica for ~ $105.00 USD, and the print quality was poor compared to the other filaments.

In the future, additive manufacturing companies must consider the environmental effects of manufacturing virgin filaments and alter their practices to include more recycled content as well as searching deeper into bio-materials. Currently, there is research being done on other bio-materials for higher-level applications such as 3D printing reactive materials for medical applications and looking into bio-composites such as bamboo and other algae plants to reinforce typical PLA.