Engineering Focus Researchers from UNSW have discovered a process to create a self-healing 3D printed plastic.
Self-healing 3D printed plastic components A team of University of New South Wales researchers, led by Professor Cyrille Boyer from the School of Chemical Engineering, discusses a novel treatment used in 3D printing that allows the material to repair itself with Manufacturers’ Monthly.
A
S additive manufacturing becomes an increasingly widespread process for various applications, what happens if a 3D printed component is damaged? How much would it cost to fix or replace, and how much downtime would it require? How much waste would it incur? According to a Macromolecules article, “Living Free-Radical Polymerization by Reversible Addition−Fragmentation Chain Transfer: The RAFT Process,” reversible addition fragmentation chain transfer (RAFT) – a form of living radical polymerisation – was discovered by the CSIRO in 1998. The CSIRO had studied linear growing systems and how to make polymer chains that incorporated a “living” group on the end. “It’s a very versatile technique that they developed, and I think it’s used in a lot of industrial applications as well, just because you can make very well controlled polymer chains
20 APRIL 2022 Manufacturers’ Monthly
and you can have very different chemical compositions and polymer chain topology,” UNSW School of Chemical Engineering researcher, Dr Nathaniel Corrigan said. Since then, several RAFT agents have been found. One class of them are known as trithiocarbonates. In a recent study led by a team at the UNSW School of Chemical Engineering, Professor Cyrille Boyer and his associates including Corrigan and PhD student Michael Zhang, found that trithiocarbonate can be used as a special additive in the liquid resin used as a material for additive manufacturing. By using this particular additive, the nanoscopic network of elements can be rearranged within 3D printed plastic that has become damaged. This fuses the broken pieces together, in response to light. “The material can grow again, as it responds to light,” Boyer said. “We decided to exploit this ability to repair the 3D printed object.”
Grow and repair With trithiocarbonate as a living group, it allowed the polymer chains to grow, according to Corrigan. “We’ve implemented trithiocarbonate because the chains are living, and when the material is broken you can regrow the
The UNSW team’s research was the first instance where a RAFT agent was used in 3D printed components. The initial aim was to reduce plastic waste for the long term in industrial applications, as broken plastic parts would not need to be discarded or recycled; they
We’ve implemented trithiocarbonate because the chains are living, and when the material is broken you can regrow the chains,” he said. “That regrowth of the chains and the regrowth of the polymer network enables the two 3D-printed fragments to re-heal together. chains,” he said. “That regrowth of the chains and the regrowth of the polymer network enables the two 3D printed fragments to re-heal together.”
could simply be repaired. “If a component fails, you can repair the material without having to throw it away,” Corrigan said. “There is an obvious environmental manmonthly.com.au
