The world produces about 734 million tons of wheat straw every year. This is a large amount of waste and is cheap. Until now, there is no clear use. Recently, the RNM-271 chemical engineering and FQM-383 NANOVAL organic chemistry research groups of the University of Cordoba have been able to give this agricultural surplus material new uses and use it as the basis for the manufacture of polyurethane foam.
This plastic material, also known as foam rubber, is usually made from petroleum by-products. It has a wide range of uses in industry and has multiple uses in the construction and automotive fields. It can be used as a sealant and heat and sound insulation materials.
This new paper, published on the cover of "Polymers" with the participation of the Chile Advanced Polymer Research Center (CIPA), has found new uses for this wheat waste. After the waste is liquefied, polyols are obtained. These polyols are one of the key compounds that play a role in the chemical reaction of making polyurethane foam.
So far, castor oil has been one of the main candidates for obtaining sustainable polyurethane foam that does not require petroleum. As one of the main authors of the paper, Esther Rincón, explained, the problem is that this vegetable oil “will not provide complete hardness and dryness once exposed to the air”, which is one of the keys to the correct formation of rubber foam.
For this reason, the new research recommends replacing wheat straw with 50% castor oil. The result is very similar to the characteristics produced by the traditional manufacturing process using non-renewable compounds: "We are able to obtain very ideal parameters in the foam manufacturing process. 96% of the wheat is converted with almost the highest performance", Esther Rincón explains. In addition, as the researchers pointed out, they have achieved a higher level of biodegradability compared to products currently on the market, which means that the decomposition time of this material is shorter.
Although these new polyurethane foams can have unlimited applications and can even be made from other types of biomass, the research team will use them in plant nurseries to help plants grow in the second phase of the research. “Instead of watering the plants, but to solve the drought problem and prevent overwatering, we inject water into the foam so that the plants can consume it as needed,” the researchers explained.
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Copyright © 2021 American Association for the Advancement of Science (AAAS)
Copyright © 2021 American Association for the Advancement of Science (AAAS)