The effects of material type and temperature factors on the adhesive bonding strength of 3D printed multi-material plastic structures

In this study, various test samples were produced using PLA based two filament materials with different fillers (2% calcium carbonate containing polylactic acid / PLA Plus and 15% carbon fiber-reinforced polylactic acid / PLA CF) and two different infill ratios (50% and 100%), in both single-material and multi-material forms. Adhesive joints of single-material and multi-material samples were formed under two different environmental conditions (room temperature and -25 degrees C). The effects of temperature changes on the adhesive bonding strength were investigated. For this purpose, mechanical tests were conducted on single lap joints conditioned at room temperature (unconditioned) and at -25 degrees C for 5 days (exposed at -25 degrees C for 120 h). The reaction of the strength values of single-material parts to temperature varies depending on the material type and infill ratio. On the other hand, for multi-materials, regardless of the infill ratio, the strength values obtained at room temperature are 11%-36% higher than those of specimens conditioned at cold temperatures. In both infill ratios and temperature conditions, it was observed that creating adhesive joints from CF-CF surfaces of multi-materials provided the highest strength. This study examines the mechanical properties (tensile strength and hardness) of multi-materials, the adhesive bonding of multi materials, and the performance of these joints. The highest bonding strength of 4.14 MPa was found in CF-CF with 100% infill ratio at room temperature and the lowest bonding strength of 2.05 MPa was found in PP-PP with 50% infill ratio at -25 degrees C.