Polyurethane is a polymer formed by the reaction of isocyanate and polyol. These polymers have a wide range of hardness, hardness and density, and are usually used to manufacture high-resilience foam seats, rigid foam insulation boards, foam seats and gaskets, elastic wheels and tires, high-performance adhesives and surface coatings. And sealant.
In terms of quantity, polyurethane foam is the most important as a soft or rigid foam, and the furniture market is the most important area. The global annual demand for furniture cushions, carpet cushions and mattresses exceeds 5 million tons.
In addition, due to the increasing use of lightweight and insulating materials in other fields such as construction, electronics, automotive and packaging materials, the global demand for polyurethane materials has continued to grow in recent years.
Key polyurethane waste
Because many harmful chemicals such as isocyanate, hydrocyanic acid and dioxins are released when these substances are incinerated, the disposal of polyurethane waste has become a problem. Polyurethane products deposited in landfills can also decompose into harmful substances that are harmful to the environment. In addition, since most polyurethanes are thermosetting polymers and will not melt when heated, it is currently difficult to recycle polyurethane.
More and more people are focusing on more sustainable production methods, so people have been researching on research strategies, such as mechanically recycling polymers (that is, turning old mattress foam into insulating materials) or chemical recycling to achieve polyurethane Of recycling.
With this in mind, the University of Illinois team led by Professor Steven Zimmerman developed a method to decompose polyurethane waste and convert it into other useful products.
Change the structure of polyols
Graduate student Ephraim Morado hopes to use chemical methods to reuse polymers to solve the problem of polyurethane waste. Unfortunately, polyurethane has extremely high stability and is made of two components that are difficult to decompose: isocyanate and polyol. Its extremely high stability makes it widely used in commerce.
Polyols are the key to the problem because they are extracted from petroleum and are not easily degraded. To avoid this difficulty, the research team adopted a chemical unit acetal that is more easily degradable and water-soluble.
The degradation products formed by dissolving the polymer with trichloroacetic acid and methylene chloride at room temperature can be used to produce new materials. As a proof of concept, Morado was able to convert elastomers widely used in packaging and automotive parts into adhesives.
The researchers will report their findings at the American Chemical Society National Conference and Exposition.
Professor Zimmerman commented that the biggest drawback of this new recycling method is the cost and toxicity of the raw materials used for the reaction. Therefore, researchers are currently trying to find a better and cheaper method to use mild solvents (such as vinegar) for degradation to achieve the same process.
Although there is still a long way to go, this is an important first step in solving the growing environmental problems.
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