3D Printing for Adhesive-Free Wood and Polymer Bonding

What if you could glue plastic to wood without adhesives or chemicals? That’s the goal of a team of researchers from Graz University of Technology in Austria. They used additive manufacturing to deposit different materials on wood, layer by layer, and called their technique “AddJoining.” These materials actually penetrated the wood, creating these extremely strong bonds. Several materials were tested, including polyamide and carbon-fiber-reinforced polyphenylene sulphide, on both oak and beech. Thanks to this technique, the team hopes to reduce the environmental impact of industrial glues and adhesives.

The glues used in industry are often synthetic, obtained from hydrocarbon derivatives and the chemical industry. As a result, they do not degrade and make recycling of certain products extremely difficult. Although so-called natural glues are becoming more and more widespread, with even initiatives around so-called biodegradable solutions, efforts are not sufficient and the reality is less green than we’d like. To combat this problem, a team of researchers in Austria has come up with the AddJoining technique.

From left to right: Awais Awan, Sergio Amancio and Gean Marcatto from the Institute of Materials Science, Joining and Forming at TU Graz (photo credits: Wolf – TU Graz).

In concrete terms, this involves depositing the material on untreated wood instead of a conventional printing plate to create joints between the two materials. You can imagine the constraints involved, but the initial results are encouraging. Gean Marcatto, one of the researchers, explains: “After the joint fractured, we were able to find polymer in the wood pores and broken wood fibers in the polymer, which suggests that the fracture occurred in the wood and polymer, but not at the joint.”