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Materials and Filaments

PLA is known to be a good all-arounder with great qualities and ease of printing. However, even with PLA, fillers and pigments can change the material properties and can even affect what it does the hardware such as the PTFE tubing, heat block, nozzle, print bed, etc. Exotic materials such as ABS, PETG, Nylon, Carbon Fiber, etc have even more considerations to keep in mind.

It would be beneficial to start with a primer on material science for the 3 most popular materials: PLA, ABS, and PETG. It is highly encouraged to learn the same for any materials not listed here.

Guides

  • Prusa has an EXCELLENT materials guide here
    • I urge EVERYONE to get familiar with this table, specially when trying new filaments, new processes, or when having issues
    • You can use the tags on the tap to further filter/refine results
  • If working with a Bambu printer and/or filament, they too have wiki entry here that also provides guidance for enclosed printers such as the X1, and whether or not the glass top should or should not be installed, which nozzles to use, and much more.
  • Bambu Filament Guide PDF: a comprehensive comparison of properties, application, and printing requirements for Bambu filaments, aiming to help users select the best-suited material for needs.
  • Bambu Filament/Printer Compatibility Guide: Guide to know what compatibility is with materials and AMS, nozzle, etc.

Material Science

Why? Because having foundational knowledge will allow one to better comprehend advanced subjects and make better decisions when choosing a model, slicing, and printing.

PLA

Polylactic Acid (PLA) is one of the most popular materials used in 3D printing, especially for Fused Deposition Modeling (FDM) or Fused Filament Fabrication (FFF) techniques. Derived primarily from renewable resources like corn starch or sugarcane, PLA is a biodegradable thermoplastic and an eco-friendly alternative to petroleum-based plastics. PLA's biodegradability combined with its ease of use has made it a favorite in the 3D printing community, particularly for hobbyists and those new to 3D printing. As with any material, understanding its properties and limitations is key to achieving the best results in 3D prints.

Molecular Structure

PLA is a polyester, and its chemical structure is made up of repeating lactic acid units. The lactic acid monomer has a chiral center, meaning it can have two different configurations, referred to as L- and D- enantiomers. The ratio of these configurations and the way they are arranged (i.e., their tacticity) can influence the properties of the resulting PLA.

Properties

  1. Physical Properties:
    • Appearance: Typically, PLA is translucent with a slightly glossy finish, though its appearance can be modified with additives.
    • Density: PLA has a density of about 1.24 g/cm³, which is relatively low compared to other plastics.
  2. Mechanical Properties:
    • Strength and Stiffness: PLA has a good tensile strength, comparable to that of polystyrene. Its stiffness is also relatively high, making it rigid.
    • Brittleness: While PLA has good strength and stiffness, it tends to be brittle, especially at lower temperatures.
  3. Thermal Properties:
    • Melting Temperature: PLA has a melting temperature in the range of 173-178°C (343-352°F), making it suitable for extrusion-based 3D printing.
    • Glass Transition Temperature: This is the temperature at which PLA changes from a hard, glassy state to a softer, rubbery state. For PLA, this is typically around 60-65°C (140-149°F).
  4. Chemical Resistance:
    • PLA is sensitive to some solvents but resistant to others. For example, it resists water and oils but can degrade in the presence of chlorinated solvents.
  5. Advantages in 3D Printing:
    • Ease of Printing: PLA's low warping characteristic and the absence of a need for a heated bed make it one of the easiest materials to print with.
    • Odor: Unlike some other plastics, PLA doesn't produce a strong or harmful odor when heated.
    • Biodegradability: As an eco-friendly material, PLA can be composted at industrial composting facilities.
  6. Challenges in 3D Printing:
    • Thermal Resistance: Due to its low glass transition temperature, PLA parts can deform if left in a hot car or exposed to similar temperatures.
    • Moisture Absorption: PLA can absorb moisture from the air, which can lead to degradation or print quality issues. Therefore, it's essential to store PLA filament in a dry environment.
  7. Modifications and Variants:
    • PLA+ or Advanced PLA: Modified versions of PLA, which claim to offer improved toughness and reduced brittleness, often by the incorporation of additives or plasticizers.
    • Filler-Modified PLA: There are PLA filaments available with various fillers, such as wood, metal powders, carbon fiber, or even glow-in-the-dark pigments, to achieve desired aesthetics or functionalities.

ABS

Acrylonitrile Butadiene Styrene (ABS) is another prevalent material in the 3D printing landscape, known for its strength, durability, and versatility. It's been widely used in various industries, from toy manufacturing (think LEGO bricks) to automotive components.

Molecular Structure

ABS is a terpolymer made up of three monomers:

  • Acrylonitrile: Provides chemical resistance and rigidity.
  • Butadiene: Imparts toughness and impact resistance.
  • Styrene: Contributes to processability and a glossy finish.

Properties

  1. Physical Properties:
    • Appearance: ABS is typically opaque with a shiny surface.
    • Density: The density of ABS is about 1.05 g/cm³.
  2. Mechanical Properties:
    • Strength: ABS boasts a good balance of strength and flexibility.
    • Durability: Known for its resistance to physical impacts and wear.
  3. Thermal Properties:
    • Melting Temperature: ABS melts at approximately 210-240°C (410-464°F).
    • Glass Transition Temperature: Around 105°C (221°F), this temperature indicates when ABS changes from a hard, glassy material to a rubbery state.
  4. Chemical Resistance:
    • ABS is resistant to many acids and bases but can be degraded by some organic solvents.
  5. Advantages in 3D Printing:
    • Durable Prints: ABS parts are durable and can withstand higher physical stresses compared to materials like PLA.
    • Post-Processing: ABS can be sanded and smoothed. A popular method for surface finishing is acetone vapor smoothing.
    • Heat Resistance: ABS parts are less likely to deform under heat compared to PLA.
  6. Challenges in 3D Printing:
    • Warping: ABS has a tendency to warp during cooling, so a heated bed is often necessary. Enclosed print chambers can also help reduce warping.
    • Odor: ABS produces a strong smell when heated, which some users find unpleasant.
    • Health Concerns: The fumes from ABS printing contain styrene, which can be harmful in high concentrations. Good ventilation is recommended.
  7. Modifications and Variants:
    • ABS+: Modified versions that claim to have reduced warping and improved adhesion between layers.
    • Flame Retardant ABS: Contains additives to increase resistance to combustion.
    • ABS/PC blends: Combine the properties of ABS and Polycarbonate (PC) to achieve improved strength and temperature resistance.

In a nutshell, while ABS presents some challenges in 3D printing, its durability and post-processing capabilities make it a preferred choice for many applications. As with all materials, mastering its unique properties and behavior is essential for optimized 3D printing results.

PETG

Polyethylene Terephthalate Glycol-modified (PETG) is a widely-used 3D printing material known for combining the ease of use seen in materials like PLA with the strength and durability closer to ABS. It's a variant of the common PET plastic, modified with glycol for enhanced properties suitable for 3D printing.

Molecular Structure

PETG is a copolyester where the basic PET structure is modified with glycol. This modification prevents crystallization, leading to a clear and amorphous structure.

Properties

  1. Physical Properties:
    • Appearance: PETG is naturally transparent, but various colors and transparencies can be achieved with additives.
    • Density: Roughly 1.27 g/cm³, it's denser than both PLA and ABS.
  2. Mechanical Properties:
    • Strength: PETG offers high strength and durability.
    • Flexibility: More flexible than PLA, making it less brittle.
    • Adhesion: Exhibits excellent layer adhesion, reducing the risk of prints splitting or layer separation.
  3. Thermal Properties:
    • Melting Temperature: Approximate range of 220-250°C (428-482°F).
    • Glass Transition Temperature: Around 80°C (176°F).
  4. Chemical Resistance:
    • PETG boasts resistance against many chemicals, including water and many organic solvents, making it suitable for various functional applications.
  5. Advantages in 3D Printing:
    • Balance of Properties: Combines ease of printing, strength, and durability.
    • Low Warping: Less prone to warping compared to ABS.
    • Transparency: The natural transparency of PETG allows for clear prints, which can be beneficial for certain applications. -Hydrophobic: Resistant to water absorption, making it preferable in humid environments.
  6. Challenges in 3D Printing:
    • Stringing/Oozing: PETG is notorious for stringing, so retraction settings in the slicer software might need fine-tuning.
    • Adhesion: While PETG sticks well to print beds, it can stick too well to certain surfaces, like PEI, and may cause damage during removal.
  7. Modifications and Variants:
    • PET: Without the glycol modification, PET is also used in 3D printing but is less common than PETG due to being more brittle.
    • Copolyesters: Variants like nGen or T-glase are related to PETG, offering specific sets of properties for diverse applications.

In conclusion, PETG is a versatile and robust 3D printing material that bridges the gap between PLA and ABS, offering a combination of ease of printing and functional strength. As always, mastering the unique print settings for PETG is crucial to achieve optimal results.