Numerous plastic products are made of polyurethanes. Fraunhofer researchers have developed a manufacturing method for polyurethanes that avoids the use of toxic isocyanates while using carbon dioxide as a starting material. Polyurethanes of reproducible standard are developed in collaboration with partners from the industry. The research results can be seen from 15 to 18 November at MEDICA 2021 in Düsseldorf (hall 3, stand E74).
Polyurethane is a multifunctional material. This type of plastic is used as foam for mattresses, as a packaging material, as an elastic material for sporting goods and as a sealing material, paint, adhesive, building foam and much more. The material is even used in medical applications – for example in the form of tubes for intravenous catheters. Researchers from the Fraunhofer Institutes for Applied Polymer Research IAP, for Chemical Technology ICT, for Manufacturing Technology and Advanced Materials IFAM and for Environmental, Safety and Energy Technology UMSICHT are now exploring new ways to produce this type of plastic sustainably and without the use of toxic materials.
Non-toxic: no isocyanates
Generally, a modular system consisting of three building blocks is used for the production of polyurethanes: isocyanates, chain extenders and polyols. The properties of the product can be controlled very precisely using recipe and process parameters. As the isocyanates are very reactive, the products can be formed in a few minutes. But there is a downside. Isocyanates are toxic and sensitizing substances that can cause allergic reactions and asthmatic symptoms. The European Chemicals Agency EChA has therefore decided to introduce a restriction: From 2023, only specially trained staff will be allowed to work with formulations containing more than 0.1 percent isocyanate.
“With our new synthesis, we avoid toxic isocyanates and thereby enable safer production processes. The polyurethane we produce in this way can also be certified as biocompatible,” explains Dr. Christoph Herfurth, a scientist at the Fraunhofer Institute for Applied Polymer Research IAP and coordinator of the project. To achieve this, the researchers replaced the isocyanates with dicarbamate. They aim to make the process efficient and industrially feasible. The research teams are now also working on more sustainable means of foaming the polyurethanes.
Sustainable: the use of carbon dioxide
“Instead of using fossil fuels, such as crude oil or natural gas, as a carbon source for the polyurethanes, we use carbon dioxide and polyurethane recycled products,” explains Herfurth. “In this way, we can recycle the carbon and ensure that a lower amount of harmful CO2 released into the atmosphere. “This process is already underway; pressures and elevated temperatures are required for this. Researchers at the Fraunhofer institutes are currently working on ways to optimize the processes.
Innovative: different protesters
Initially, the project team will focus on developing the building blocks for polyurethane production. The researchers will also investigate the relationship between the process parameters and structural properties: How do you achieve the properties that make conventional polyurethanes so versatile? Three different demonstrators will illustrate the different uses of this new form of polyurethane: The first will be sustainable tubes for medical applications. Only relatively small amounts of polyurethanes are needed here. It makes it easier to launch a new product. In another application, adhesives at Fraunhofer IFAM are being developed optimized for the new polyurethanes so that needles can be glued to medical tubing, for example to catheters. The third demonstrator on the agenda is foam and thus processing technologies for mass-produced products.
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Provided by Fraunhofer-Gesellschaft
Citation: From Medical Applications to Sporting Goods: Biocompatible and Sustainable Plastics (2021, November 2) Retrieved November 2, 2021 from https://phys.org/news/2021-11-medical-applications-sporting-goods-biocompatible.html
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