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This study demonstrated a freeform fabrication of porous hydrophobic polyethylene parts by three-dimensional printing technique, using water-based binder. This involved initially making a green structure by printing a binder onto the mixture of polyethylene and water soluble adhesive powder bed. The green structure was thermal treated to melt polyethylene fraction to achieve a well-connected structure within the part. Adhesive components were then leached out in water, leaving only porous structure of polyethylene. Specimens with ratios of polyethylene to adhesive from 80:20 to 20:80 were fabricated and characterized. It was found that increasing polyethylene content increased density, modulus, and strength while decreased porosity. Preliminary in vitro toxicity test of porous parts using L929 cells showed that the cells that were in contact with samples were healthy. No inhibition zone was observed.

Over the past few years due to increased environmental awareness, there has been great interest in improving ceramic processing to reduce the use of organic solvent and synthetic binders. This work is focused on a gel-casting process using a biopolymer that is environmentally friendly, easy to burn out and inexpensive. Starch was employed as a binder and kaolin clay was used as the starting material. To fabricate kaolin spheres, aqueous kaolin slurry was mixed with a starch solution. A small volume of the kaolin-starch solution was added to a vegetable oil at high temperature. The starch then formed a strong, cross-linked gel and immobilized the clay powders into the desired spherical shape. The kaolin spheres were then dried and sintered at different temperatures for 1 h. The phases present in the spheres was identified by X-ray diffraction (XRD) analysis. The microstructure and dimensions of the kaolin spheres were examined using a field emission scanning electron microscope (FE-SEM) in conjunction with energy dispersive spectrometry (EDS). An image analysis technique was used to identify the pore volume of the spheres.

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