부산대학교 도서관

There are a limited number of thermoplastics with intrinsic shape memory effect (SME) that are four-dimensional (4D) printable. Development of other shape memory polymers (SMPs) entails synthesis with a complicated chemical experimental lab effort. In this paper, for the first time, a novel layered multi-material structure is developed based on a deep comprehension of SMEs’ macromolecular requisites. The fused deposition modeling (FDM) method is used for the four-dimensional printing of layered structures whose base materials show no SME. Commercial acrylonitrile butadiene styrene (ABS), toughened ABS-thermoplastic polyurethane (TPU) blend, and TPU, all with no SME, are used to fabricate bi-layers of ABSTPU blends and TPU with different volumetric proportions. Different thermo-mechanical tests, including dynamic mechanical thermal analysis (DMTA), and constrained and free shape recovery, are conducted. Also, the interfacial properties of the layered 4D printed structure are assessed by the mean of shear testing and scanning electron microscopy (SEM). Experimental results reveal that the 4D printed bi-layer composites possess a high level of programmability, SME (90–96%), and perfect interfaces without any porosity and detachment between layers. The results of this research can potentially eliminate the desperate need for SMPs for 4D printing and broaden the opportunity to have smart parts using commercial thermoplastics.