American engineers have developed a method of 3D printing with one polymer, which allows to “program” the reaction of the printed subject matter on heating. The method is based on the compression dependence of printed polymer layers, the direction of passage of the extruder during printing. The structures used thus, can be used to quickly change their shape when heated, say the authors of the articlepresented at the conference CHI 2019.
Usually 3D printing means after printing and curing of the object properties remain unchanged throughout a cycle of use. But there are production methods that allow you to specify the future behaviour of the created object. For example, it is possible to use an alloy with shape memory. In addition, there is another approach that allows you to apply many materials. It is based on the combination of two materials with different reactions to external stimuli. For example, this can be a expanding from increased humidity or temperature.
Linin Yao (Yao Lining) and her colleagues from the University Carnegie Mellon in their work chose a similar approach and showed that it is possible to use a single material, which in this case is a polylactide. As the material of 3D printing it exhibits interesting properties. During application of the strip polylactide through an extruder, a new layer of material is stretched, bound with the previous layer and solidifies as such. If you then heat the printed object above the glass transition temperature (for used in the work of polylactide she is 61 degrees Celsius), there will be stress relaxation and the stretched layer will be compressed along the direction of printing.