Shape memory effect of three-dimensional printed products based on polypropylene/nylon 6 alloy

Based on the rapid development of three-dimensional (3D) printing, the fabrication of the 3D printed products which can change their shapes over time has been termed as four-dimensional (4D) printing. Since the functionality is generally limited by available materials, especially for fused deposition modeling (FDM, a trendy technology of 3D printing), it has aroused widespread requirements to develop a novel filament with excellent properties and functionalities. In this study, polypropylene/nylon 6 (PP/PA6) alloy was fabricated as a candidate for FDM and maleic anhydride-grafted poly(ethylene-octene) (POE-g-MAH) was used as a modifying agent as well as a compatibilizer. The results showed that the PP/PA6 alloy with 30wt% of PA6 on the basis of the certain mass ratio of PP and POE-g-MAH (1.5:1) exhibited a high dimensional stability and appropriate mechanical properties in FDM. In addition, the possibility of PP/PA6 alloy as a shape memory polymer blend and the mechanism of shape memory effect (SME) were investigated. The 3D printed product with 30wt% of PA6 fabricated by the infill orientation of 45 degrees/-45 degrees and 100% infill density exhibited a great SME with the deformation temperature (T-d) of 175 degrees C. This simple method for preparation of a novel filament with shape memory performance based on PP/PA6 alloy has a vast potential for the development of 4D printing technology.