This page collates the material investigations that I have undertaken for this project. In initial phases of this, the focus was primarily on producing a product that would be compatible with Fused Deposition Modeling (FDM) printers. These are the most common form of 3D printers, which melt thermoplastics and lay down layers to create forms.
As such, the bulk of the investigation was focused on comparing standard FDM plastic compositions for performance analysis. However, as the project was underway, goals shifted into deeper explorations of the gyroid form itself, non-standard FDM materials were selected for later analysis, availability permitting.
The conditions of the project - needing the material to act both as structural support as well as a growing medium, makes material selection critical. It must be be water and UV resistant and provide long term structural stability while under load. This must be balanced against the difficulty and cost of using the material, especially in large scale applications.
While scale prototypes were printed using PLA, for large scale testing ASA will be used. It provides the proper environmental resistances and structural properties, while still being able to be printed on standard FDM printers.
FDM Materials
ASA (Acrylonitrile Styrene Acrylate)
Pros:
- UV resistant
- Weather resistant
- Good mechanical properties
- Not prone to stress cracking
- Less prone to warping than ABS
- UV resistant
- Weather resistant
- Good mechanical properties
- Not prone to stress cracking
- Less prone to warping than ABS
Cons:
- Requires higher printing temperatures
- Can produce strong odors during printing
- Needs heated bed and potentially an enclosure (debatable)
- More expensive than ABS
- Requires higher printing temperatures
- Can produce strong odors during printing
- Needs heated bed and potentially an enclosure (debatable)
- More expensive than ABS
ABS (Acrylonitrile Butadiene Styrene
Pros:
- High strength and impact resistance
- Good heat resistance
- Easily post-processed
- Suitable for functional parts
- Good heat resistance
- Easily post-processed
- Suitable for functional parts
Cons:
- High shrinkage and warping
- Requires heated bed and enclosure
- Strong odor and fumes
- Not biodegradable
- Requires heated bed and enclosure
- Strong odor and fumes
- Not biodegradable
Nylon
Pros:
- High strength and durability
- Excellent layer adhesion
- Good chemical resistance
- Abrasion resistant
- Excellent layer adhesion
- Good chemical resistance
- Abrasion resistant
Cons:
- Highly hygroscopic
- Warping and shrinkage issues
- Requires high printing temperatures
- Can be difficult to adhere to the print bed
- Warping and shrinkage issues
- Requires high printing temperatures
- Can be difficult to adhere to the print bed
PC (Polycarbonate)
Pros:
- Extremely strong and durable
- High heat resistance
- Good electrical insulation
- Transparent variants available
- High heat resistance
- Good electrical insulation
- Transparent variants available
Cons:
- Difficult to print (high temperatures, prone to warping)
- Moisture sensitive
- Requires enclosed printing environment
- Limited flexibility
- Moisture sensitive
- Requires enclosed printing environment
- Limited flexibility
PP (Polypropylene)
Pros:
- Lightweight
- Good chemical resistance
- Fatigue resistant
- Semi-flexible
- Good chemical resistance
- Fatigue resistant
- Semi-flexible
Cons:
- Poor bed adhesion
- High shrinkage rate
- Warping issues
- Limited strength in printed parts
- High shrinkage rate
- Warping issues
- Limited strength in printed parts
PLA (Polylactic Acid)
Pros:
- Biodegradable, eco-friendly
- Easy to print, low warping
- Low odor
- Good detail resolution
- lots of formulations
- Easy to print, low warping
- Low odor
- Good detail resolution
- lots of formulations
Cons:
- Low heat resistance
- Brittle
- Poor UV resistance
- Limited functional use
- prone to stress fracturing
- low glass phase temperature
- Brittle
- Poor UV resistance
- Limited functional use
- prone to stress fracturing
- low glass phase temperature
TPU/TPE (Thermoplastic Polyurethane/Elastomer)
Pros:
- Flexible and elastic
- Abrasion resistant
- Chemical resistant
- Good layer adhesion
- Abrasion resistant
- Chemical resistant
- Good layer adhesion
Cons:
- Difficult to print (slow speeds required)
- Moisture sensitive
- Can be stringy
- Limited overhang performance
- Moisture sensitive
- Can be stringy
- Limited overhang performance
PETG (Polyethylene Terephthalate Glycol)
Pros:
- Good strength and durability
- Chemical resistance
- Food safe (when pure)
- Low shrinkage
- Chemical resistance
- Food safe (when pure)
- Low shrinkage
Cons:
- Can be stringy
- Moisture sensitive
- Less rigid than ABS
- Slightly harder to print than PLA
- Moisture sensitive
- Less rigid than ABS
- Slightly harder to print than PLA
Pros:
- Good impact resistance
- Lightweight
- Dissolvable in limonene (useful as support material)
- Similar printing characteristics to ABS
- Lightweight
- Dissolvable in limonene (useful as support material)
- Similar printing characteristics to ABS
Cons:
- Limited strength
- Prone to warping
- Requires heated bed and enclosure
- Not UV resistant
- Prone to warping
- Requires heated bed and enclosure
- Not UV resistant
Non-Standard / Non-FDM Materials
FreeFoam Expanding Printed Foam
This is a proprietary material formulated by ETEC. It is a photopolymer resin with heat activated foaming agents. Once printed, lattice structures can be heated, at which point they will expand equally providing a 30%-50% increase in size. This also creates pores in the foam, allowing it to be doped with other materials.
This is interesting for the investigation of the gyroid as a non-structural internal lattice that can be shipped more efficently and then expanded on site. I am interested in this for its possible use for carrying and holding water, acting as a sponge and a growing form for plantings.
Concrete / Ceramic Printing
As the gyroid form came more to the forefront of the project, I began to investigate using it as the primary expression of the wall system, instead of just an internal structure. This provided an opportunity to look at non 3D printed and non-plastic based materials. Printing the gyroid in concrete or ceramic would provide exceptional structural properties, and the porous nature of the cement and ceramic would allow for the gyroid to diffuse water, instead of merely carrying it as a plastic-based solution does.PBAT-Based PLA with Fertilizer Release
Silva, et al “Development of Biodegradable PLA/PBAT-Based Filaments for Fertilizer Release for Agricultural Applications.” Materials 15, no. 19 (September 29, 2022): 6764. https://doi.org/10.3390/ma15196764.
This material is based off of this academic paper, which looked at the possible integration of micro-encapsulated fertilizer with PLA printing plastics. Their study tracked the expression rate of the fertilizer in water as the PLA. As the PLA began to get microscopic cracks, the fertilizer compounds were released into the water. This would provide not only a structural medium for plant growth but also continually provide them with fertilizers to promote more rapid growth.
Loss Casting Brick Form
The current programming of the parametric gyroid allows for the creation of a 3D printable positive and negative version. It would be interesting to experiment with using these as formwork for fired bricks. These would have similar benefits to the concrete/ceramic approach while still allowing for broad spread use with common FDM printers. The use as a lost casting would also remove the need for more expensive ASA over PLA. There is also the possibility to integrate the gyroid bricks into standard brick walls, leading to interesting forms and planting conditions.