Additive manufacturing or 3D printing is the process of depositing material layer-by-layer to create 3-dimensional products. When creating 3D-printed products from two or more materials, multi-material additive manufacturing processes are used which eliminate the need for assembly operations. Fused filament fabrication multi-material additive manufacturing permits the production of a single printed item employing multiple materials in fused filament fabrication. This work studied the factors affecting fused filament fabrication multi-material additive manufacturing, by reviewing existing works, designing part(s), conducting design of experiments, and carrying out parts’ performance test. An E3D multi-material filament 3D printer was utilised throughout this study. The chosen polymer combination was polycarbonate (PC) and poly(methyl methacrylate) (PMMA), whilst the design and testing of the multi-material parts was limited to lap-shear testing. Results showed that the interface bonding of the PMMA/PC (PMMA printed first and followed by PC) specimens was stronger than the one of the PC/PMMA specimens. Furthermore, to investigate the effect of the contact or overlapping area on the interface bonding strength, PMMA/PC specimens with varying dimensions were designed, printed, and tested. When the contact area was reduced, a strong interface bonding between the PMMA and PC layers was still maintained.

This study investigates the physical and mechanical properties of biodegradable composites based on PLA/PHBV blends modified with different content of nanocrystalline cellulose (NCC) of 5, 10, and 15 wt.%. Density measurements reveal that the density of the composite increases with increasing NCC content. Water absorption tests demonstrate a gradual increase in the composite water content with increasing incubation time, reaching stabilization after approximately 30 days. Mechanical testing was also carried out on both on conditioned samples after the process of hydrolytic degradation and accelerated thermal aging. The conditioned composites show an increase in the stiffness of the materials with increasing content of nanocrystalline cellulose. The ability to deform and the ability to absorb energy when the sample is dynamically loaded decrease. The repeated strength tests, after the process of incubation of samples in water and after the process of accelerated thermal aging, show the degradation of composite materials; however, it is noticed that the introduction of cellulose addition reduces the impact of the applied artificial environment in aging tests. The findings of this study indicate promising applications for these types of materials, characterized by high strength and biodegradability under appropriate conditions. Household items such as various containers or reusable packaging represent potential applications of these composites.