3D printing or additive manufacturing is receiving growing interest due to factors such as the design flexibility it allows, fast prototyping, and the potential for broader application of bioplastics. 3D printing generally refers to a class of manufacturing techniques whereby an object is produced by printing materials in layers that are joined to achieve the final desired object.
Producing objects with 3D printing requires relatively lower investment costs for varied designs. Compared to injection molding, where specific molds need to be created for each object. The molds are usually expensive and intended for mass production. Whereas in 3D printing molds are not required.
An inventor can conceive a product today, have it modeled in CAD, send the design to a 3D printer, and have the prototype ready within a day. If that prototype is made using a biodegradable bioplastics like the VEOfiber Premium 3D, it does not become an environmental problem at the end of its use. It can simply be recycled or used for compost.
Bioplastics have been used in a wider range of 3D printing methods in different research studies to explore diverse ways of processing bioplastics. However, the properties of most bioplastics currently limit the 3D printing of bioplastics to certain methods.
The 3D printing methods that are frequently used for bioplastics are material extrusion methods, inkjet 3D printing, and 3D spinning. Material extrusion methods are diverse and the most widely used. Examples are fused filament fabrication(FFF), fused deposition modeling (FDM), direct ink writing (DIW), and micro-extrusion 3D bioprinting. Table 1 summarizes these three categories of 3D printing methods.
Table 1. 3D printing methods most frequently used for bioplastics
Material Extrusion Method
Inkjet 3D Printing
– An extrudable material is dispensed through a nozzle and deposited layer by layer.
Example: FDM (fused deposition modeling), SLA (Stereolithography), and DIW (direct ink writing)
|– Micron-sized liquid droplets expelled by acoustic or thermal forces are deposited onto a user-defined location on a substrate.
Example: Binder jetting process
|– The polymer solution is spun into stacked filaments from a needle.
Example: wet 3D spinning and 3D electrospinning
Thus far, FDM material extrusion method has been most widely used because it allows the bioplastic to be mixed with other materials more effectively. Since it is also compatible with 3D printing of other nonbiodegradable plastics such as ABS and PET, it is more economical to purchase an FDM 3D printer for wider options. Some examples of bioplastics formulations and the 3D printing technique they have been used in are listed in Table 2.
One of the limitations of 3D printing with bioplastics is the difficulty in producing the thin filaments required for the material extrusion method commonly used for 3D printing with bioplastics. The filaments need to be produced using the conventional extrusion method and this is associated with the problem of die swell. A defect that results from extrusion of viscous material through the extruder nozzle which has a small diameter.
Other defects such as part warpage, low agglomeration between layers, and poor mechanical properties of the 3D printed parts result when bioplastics are not well formulated for 3D printing. The challenge is therefore to engineer the bioplastic formulations such that they are optimized specifically for 3D printing. This reduces the chance of defects occurring. Blends and composite formulations are optimized for specific processing techniques and applications.
Some methods such as 3D wet spinning require the bioplastics to be dissolved in solvents. This in most cases requires the use of environmentally hazardous solvents, such as chloroform and tetrahydrofuran. More eco-friendly solvents should be explored when using such 3D printing methods.
Major improvement in 3D printing in recent years has been the advancement of the process to allow for a wider array of materials to be 3D printed. The range of design achievable using the 3D printing technique has also broadened in recent years. From miniature-sized objects to buildings to space rockets, 3D printing has been used to produce almost everything.
Improved directionality in the process, improved mechanical properties, and less warping has been achieved thanks to development in different aspects as discussed in the following sections.
Biocomposites and blends can have superior properties such as breathability, superior strength, improved optical strength, and overall improved performance compared to neat bioplastics. Some biocomposite formulations are listed in Table 2.
Table 2. Some bioplastic formulations, 3D printing techniques, and potential applications
|Bioplastic composite/ blends
||3D Printing method
|PLA/ wood flour||FFF/FDM||Applications requiring load-bearing or other functional use|
|PLA/ cotton cellulose||FDM||Automotive|
|PHBHHx / PCL||Computer-aided wet spinning||Biomedical scaffolds|
|P4HB / PHOH||SLA||Heart Valve – subclavian artery|
|PHBV / calcium phosphate nanoparticles/gelatin||SLS||3D scaffold with an extra-cellular matrix structure|
|PHBV / wood flour||FDM||Filaments|
|PCL / Cocoa shell waste||FDM||Biomedical application and household use|
Biocomposites are made by formulating bioplastics with fibers and minerals to form a material with properties that are different from that of the individual component materials. In biocomposite, one material serves as the continuous phase, the matrix, while another material served as the dispersed phase, the fiber or mineral. An example of a composite formulation is PHA with eggshell powder.
Blends refer to a formulation that is achieved by combining two bioplastics both serving as continuous phases. For example a blend of PLA and PBAT or a blend of PVA and PLA. These blends and composites are aimed at achieving processibility, performance, and/or biodegradability that is not achievable by the bioplastic in its neat form.
Since there are several types of 3D printing processes, bioplastic resins specially formulated for specific 3D printing methods have been developed. Examples include the development of curable PHB resin that allows biopolymers to be applied in 3D printing methods that require photocuring.
Since 3D printing methods like SLA requires the plastic to be hardened by exposure to light, this limits this particular 3D printing method to photocurable plastics. Therefore some researchers have explored developing photocurable bioplastics like photocrosslinkable PLLA.
VEnvirotech’s VEOfiber premium 3D bioplastic range is optimized for 3D prininting using the FDM/FFF 3D printing method. FDM/FF method does not require use of solvent of photocuring, rather on the thermal and mechanical properties of the material.
Nanocellulose in particular has been promising in 3D printing of bioplastics. Biocomposites made using nanocellulose show significant improvements in thermal and mechanical properties which make them better suited for 3D printing. Nanocellulose is particularly attractive because cellulose is relatively abundant in nature.
Other nanoparticles include hydroxyapatite nanoparticles, graphene nanoparticles, and carbon nanotubes amongst others. At the nanoscale, these materials present different effects on the biocomposite compared to biocomposites prepared with larger particles. This often results in materials with exceptional properties.
Stimuli-responsive materials have been developed using biocompatible bioplastic composites. These achieve 4-dimensional printing by first 3D printing the objects. The printed object is then remodeled and matured in the 4D printing process.
This achieves a complex tissue that better mimics real tissues by changing shape and features in response to stimuli. The stimuli can be chemical, physical, or biological. This has promising applications in tissue repair, replacement, and enhanced growth.
With the biotechnological advancement that allows for better control over the chemical structure and hence mechanical properties of bioplastics, it becomes more possible to better tune bioplastics to improve their compatibility with 3D printing.
Bioplastics are already being applied for biomedical applications such as the production of bone tissue scaffolds. We expect to see this advance toward 3D and 4D printing of more complex tissue which better replicates real tissues. Biocompatibility and biodegradability of bioplastics play a significant role in such applications. PLA, PHA, and PCL are some of the bioplastics that are used.
In food, 3D printing has been applied to 3D printing of tissue-cultured meat and other foods. This is presented as part of the effort to find alternative ways to make food available to people in a cost-effective, hygienic, and environmentally friendly way. When it comes to food, such ideas are more likely to be acceptable to consumers when the raw materials used are naturally sourced.
This is bioplastic grade optimized for FDM/FFF 3D printing method. Its unique formulation comprises 30% natural fibers recovered from organic waste from food processing, brewery, and other industries. The VEOfiber premium 3D has 3D printability superior to that of PLA. This innovative material combines sustainability and superior performance.
Contact us today for information on the VEOfiber Premium 3D and other products and services offered by VEnvirotech.