In the fall of 2010, as part of my Mechanics of Solids course, I undertook a project examining the mechanical properties of baking soda-superglue composites. I’d first heard of using baking soda and superglue together through an interview with Adam Savage (of MythBusters fame) published in MAKE: Magazine. Savage listed it as one of his favorite maker “tricks” – simply layering superglue and baking soda to make a versatile material that could be used to attach, fill gaps, pot or rebuild. I have subsequently used this technique in a wide variety of situations, from eyeglass repair to prototyping.
My goals in this project were to: a) determine the optimal production method for this material, b) determine what mechanical properties of the material would be of greatest interest given the material’s uses, and c) rigorously determine those mechanical properties. It became clear early on in the project that the optimal method of production – a “layering” process in which alternate layers of superglue and baking soda are built up – would make anisotropy in the material a significant concern. Consequently, basic tensile tests (following ASTM D638) were conducted with tension applied both normal to the layer plane and parallel to the layer plane.
Results indicated an average modulus of elasticity of 27.5 kPsi for the tension-parallel samples (17.1 kPsi for tension-normal samples), and an average ultimate strength of 2.49 kPsi (1.04 kPsi). Although the strength of the material normal to the layer plane is significantly lower than that parallel to the layer plane, it is still unclear whether anisotropy is a concern, primarily because of inconsistencies in the tension-normal samples.
This project was made possible by the generosity of Permabond Engineering Adhesives, which donated 2 lbs. of Permabond 268 superglue for use in this project.