| TECHNOLOGY |
The Japanese research team "chose coffee grounds and molasses as raw materials because of their compatibility with the environment and their large production amounts. WORLD OUTPUT of coffee grounds is approximately 6 million tons per year and that of molasses is about 30 million tons per year—plenty to satisfy world demand. Coffee grounds are by-products of the production of instant coffee and coffee drinks. Molasses is a by-product of the sugar industry. Some molasses is used in the production of alcohol, animal feed, and fertilizers, but some is disposed of in the ocean, he said. To make polyurethane composites, the Japanese researchers first prepare a molasses-polyol from molasses and polyethylene glycol. Alternatively, they can make a lignin-polyol from kraft lignin (a by-product of pulp production to make paper) and polyethylene glycol. Coffee grounds are then added to either of the two polyols at a concentration of up to 90%. The mixture is reacted with diphenylmethane diisocyanate and a catalytic amount of dibutyltin. To make flexible polyurethane foams, the researchers blend molasses with polyethylene glycol. This combination is then mixed with a polyol such as polypropylene glycol, a graft polyol, or a polyester polyol. The mixture is reacted with an isocyanate such as toluene diisocyanate, hexamethylene diisocyanate, or lysine diisocyanate in the presence of small amounts of silicone surfactant, catalysts, and water. Inorganic fillers such as barium sulfate can be added to increase rigidity. By these methods, it is possible to synthesize biodegradable polyurethanes and foams, "Biodegradation starts easily from the saccharide part in the polyurethane molecular chain." The saccharides are derived from the sucrose, glucose, and fructose units that are the major components of molasses. In addition, the pyranose and furanose structures in the saccharides in the molasses give rigidity and toughness to the polyurethane component of the composite. "By changing the amount of saccharides in the polyurethane, it is possible to control thermal and mechanical properties," THE COFFEE GROUNDS improve the composites' mechanical properties such as strength and elasticity. "The grounds' regular particle size is crucial to produce composites with uniform quality." He noted that polyurethane foams and composites incorporating these biowastes are competitively priced. Flexible polyurethane kitchen sponges made from molasses are already being marketed in Japan. |
| UPDATE | 01.01 |
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