The powdered additive the UNSW team use is a trithiocarbonate, known as a reversible addition fragmentation chain transfer (RAFT) agent which was originally developed by CSIRO. The RAFT agent enables rearrangement of the nanoscopic network of elements that make up the material and allows the broken pieces to be fused. This occurs within approximately 30 minutes when UV LED lights are shone directly onto the broken plastic, with full healing taking place after roughly one hour.
Experiments, including on a 3D printed violin, show that the self-repaired plastic’s strength is fully recovered compared to its original unbroken state. The team said commercialisation of the process is possible given the simplification and speed of their system compared to existing ways of repairing broken 3D printed materials. "There are other processes that do this, but they rely on thermal chemistry to repair the material and typically it takes around 24 hours and multiple heating cycles to achieve the same type of result," Dr Corrigan said. "Another restriction to that is that you need an oven which is heated to high temperature and you obviously cannot repair the plastic material in situ – you would need to disassemble it from the component first which adds a level of complexity and delay. With our system, you can leave the broken plastic in place and shine the light on the entire component. Only the additives at the surface of the material are affected, so it’s easier and also speeds up the entire process."
Professor Boyer says the new technology could potentially be used in a range of applications where advanced 3D printed materials are currently used in high-tech specialised components. These include wearable electronics, sensors, and even some shoe manufacturing.