DLP-printable fully biobased soybean oil composites

Composites reinforced with micro-particles are widely used in engineering fields. Unfortunately, the traditional manufacturing processes do not allow customization and shape complexity achievable with additive manufacturing technologies. In particular, VAT polymerization enables the highest printing resolution. Here, we demonstrate the fabrication of fully-biobased composites consisting of a matrix of acrylated soybean oil (ASO) and a lignocellulose waste derived from the macadamia nut industry (macadamia nut-shell, MAC) as reinforcing agent. Different formulations were prepared by varying the content of MAC, and their reactivity was evaluated by means of Fourier transform infrared spectroscopy and photorheology. The suitability of the formulated novel biobased inks for digital light processing (DLP) 3D-printing was illustrated by successful printing of complex 3D-structures with a high resolution. The thermo-mechanical and mechanical properties of the 3D-printed composites were tested by DSC, DMTA and tensile tests, which revealed that. increasing MAC contents reflected into higher glass transition temperatures, ranging from 25 to 46 °C, and higher Young's modulus, ranging from 15 to 100 MPa. The morphology of the samples and the dispersion of the MAC in the ASO network was investigated by field emission scanning electron microscopy, while the surface roughness of the printed composites was analysed with profilometry. Cytotoxicity, cell adhesion and cell proliferation tests with human fibroblast cells were carried out in view of the fabrication of scaffolds for bioengineering and the results envisage good potential for these fully bio-based composites in the biomedical field.