Explorative research for new biobased binders in 3d printing

Abstract

Currently, there is a shift toward using more biobased materials in 3D printing, which presents an eco-friendly alternative to traditional plastics due to their potential for benefits such as waste reduction, biodegradability, and reduced toxicity. However, challenges such as mechanical strength, structural integrity, and water resistance still pose hurdles to their widespread adoption. Therefore, this study aimed to develop methods to find and optimize novel natural binder formulations that enhance the structural integrity, water resistance, and durability of biobased 3D-printed objects. The focus of this research was to use natural binders and combine them with fillers derived from biobased waste streams. Initial research identified Latex, Linseed Oil, Pine Resin, Lignin, and Casein glue as promising binders. Tests resulted in casein glue, a milk protein derived from cows, mixed with calcium carbonate (CaCO3) from oyster seashells as the bestperforming combination. Further exploration revealed that adding cork as an additional filler significantly improved the viscosity, workability, and performance of the paste. From there, two successful formulations emerged: a cork-dominant paste and a CaCO3-dominant paste. Water absorption tests were conducted and resulted in the CaCO3-dominant paste being more waterresistant and structurally sound, despite absorbing more water, compared to the cork-dominant paste, which exhibits increased rigidity at the cost of being prone to cracking and deformation when drying. In collaboration with BESE and Biobased Creations, prototypes were developed that demonstrated their potential application in the biobased building sector. Through a set of experiments, this study highlights the impact of external factors such as environmental conditions, printer settings, and lab equipment on the performance of the paste. Future research should focus on optimizing cork and calcium carbonate ratios, experimenting with the casein glue mixture, testing other fillers, conducting mechanical and biodegradability tests, and exploring crosslinking and biobased waterproofing coatings to enhance material properties. These findings aim to set a framework for investigating new potential binders and creating binder formulations for biobased 3D printing.