Material and surface roughness effects on adhesion of thermoplastic-elastomeric interfaces for dissimilar material 3D printing

Dissimilar material 3D printing (DMP) can combine polymers with dissimilar properties into functional parts. However, DMP requires an understanding of adhesion at the interface to ensure performance. To quantify the adhesion between polymers with dissimilar mechanical properties, a modified double cantilever beam (DCB) test was performed between 3D printed thermoplastic layers and a cast layer of hydroxyl-terminated polybutadiene (HTPB). The effect of surface roughness on the fracture toughness was determined with polyvinylidene fluoride (PVDF) samples using one machined and three printed surfaces. There were no significant differences in surface roughness or fracture toughness between the print surfaces, but the failure type changed. The 5 and 10 wt.% polycaprolactone (PCL)/PVDF blends and the stiffness matched polylactic acid (PLA) interfaces rarely failed in mode I, indicating improved adhesion. This work provides a framework to assess the factors driving the adhesion of thermoplastic-elastomeric interfaces produced via polymer DMP, which is underexplored in literature.