Cellulose is, by all means, the basis of printing world, it is the main ingredient of paper and thus holds the backbone of printing. However, as the world is changing at a rapid rate, demands for better substitutes is also coming in view. This rising demand was recently met by a team of researchers at MIT when they came up with a renewable and biodegradable substitute for polymers that are presently being used in 3D printing. As the paper was authored by an MIT researcher, Sebastian Pattinson and an MIT associate professor, A. John Hart, they were able to explain the ins and outs of this new research in a detailed manner.
As Pattison likes to explain, “Cellulose is the most important component in giving wood its mechanical properties. And because it’s so inexpensive, it’s bio-renewable, biodegradable and also very chemically versatile; it’s used in a lot of products. Cellulose and its derivatives are used in pharmaceuticals, medical devices, as food additives, building materials, clothing—all sorts of different areas. And a lot of these kinds of products would benefit from the kind of customization that additive manufacturing enables.”
Usage of cellulose as an additive manufacturing substance is not a new concept, there were many who attempted to do this but fell flat face to dead end. One of the major reasons is that when cellulose is heated, it decomposes thermally before turning into a flowy substance, partially because of the hydrogen bonds that are present between the cellulose molecules. The intermolecular bonding is also used in making of high-concentration cellulose solutions that are very viscous and can be extruded with great ease. Despite that, the MIT researchers team decided to go with cellulose acetate – an easily formed material from cellulose and is available in abundance anywhere anytime.
The number of hydrogen bonds in this substance are brought down by acetate groups. Cellulose acetate is easily soluble in acetone and can be extruded through nozzles simply. As acetone evaporates within moments, the cellulose acetate solidifies then and there. Further processing replaces the acetate groups and enhances the strength of printed parts. Pattison further explains, “After we 3D print, we restore the hydrogen bonding network through a sodium hydroxide treatment. We find that the strength and toughness of the parts we get … are greater than many commonly used materials.” The materials included polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS).
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