Seeing as how many 3D printing thermoplastics are reliant on oil, they present a series of problems. Some of these issues are environmental and others relate to a lack of renewability due to fossil fuel depletion. Materials research initiatives are looking to remedy these shortcomings and it appears they may have found a worthy contender. Kaunas University of Technology and Vilnius University in Lithuania invented a process for creating photopolymer resins made from soybean oil- and lignin-based materials, presenting a renewable and sustainable source of plastics.
As another earlier paper from Kaunus University states:
Natural oils are one of the most extensively used renewable feedstocks, because of their availability, relatively low cost, chemical functionality, and easy processing. Vegetable oil-based polymers are considered as potentially biocompatible materials because the incorporation of vegetable oil moiety can enhance biodegradation of the materials. Soybean oil is the most common vegetable oil source in America, comprising around 57% of all vegetable oil resources.
This paper had a similar rationale in their choice of soy resin materials. Another reason they turned to this particular strain of ingredients is due to the possibility of polymerizing double bonds. Thus they chose acrylated epoxidized soybean oil (AESO), a material curable via ultraviolet light or electron beams. They also explored mixtures of AESO with vanillin dimethacrylate (VDM) or vanillin diacrylate (VDA), consisting of lignin. Although, the researchers found that the pure AESO had a higher rate of photocross-linking.
Sustainable Printing
The team tested the materials using direct laser writing 3D lithography, developing various microscale objects. They were able to 3D print microscale bridge objects using ultra-fast laser pulses. The researchers achieved a resolutiong of 1 micron with a speed of 6900 voxels/second. They also tested out various iterations of the soy resins and found that certain additions like VDM altered the glass transition temperature unfavourably but adding that it could serve as a plasticizer for AESO.
One of the advantages of the new method is that it avoids the use of toxic photoinitiators. This makes prints far more useful in medicine and biotech as it increases the integrity of biodegradable cell-growth scaffolds and reduces the auto-fluorescence while performing microscopy. They have far more optical resilience and don’t suffer from signal losses. The use of plant-derived materials also benefits from low toxicity, high biodegradability and better recycling options.
Featured image courtesy of the researchers. Full paper available here.
