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Polyurethane foam (PU) is commonly used in construction for a variety of purposes, but with the push toward zero emissions, environmentally friendly materials are receiving increasing attention. Improving their green reputation is critical.
Polyurethane foam is a polymer consisting of organic monomer units linked by urethane. Polyurethane is a lightweight material with a high air content and an open-cell structure. Polyurethane is produced by the reaction of a diisocyanate or triisocyanate and polyols and can be modified by the inclusion of other materials.
Polystyrene foam can be made from polyurethane of varying hardness, and other materials can also be used in its production. Thermoset polyurethane foam is the most common type, but some thermoplastic polymers also exist. The main benefits of thermoset foam are its fire resistance, versatility and durability.
Polyurethane foam is widely used in the construction industry due to its fire-resistant, lightweight structural and insulating properties. It is used to make strong but lightweight building elements and can improve the aesthetic properties of buildings.
Many types of furniture and carpeting contain polyurethane due to its versatility, cost-effectiveness and durability. EPA regulations require the material to be fully cured to stop the initial reaction and avoid toxicity problems. In addition, polyurethane foam can improve the fire resistance of bedding and furniture.
Spray polyurethane foam (SPF) is a primary insulation material that improves a building’s energy efficiency and occupant comfort. Using these insulation materials reduces greenhouse gas emissions and improves indoor air quality.
PU-based adhesives are also used in the production of wood products such as MDF, OSB and chipboard. The versatility of PU means that it can be used for various purposes such as sound insulation and wear resistance, extreme temperature resistance, mildew resistance, aging resistance, etc. This material has many uses in the construction industry.
Although polyurethane foam is very useful and is used in many aspects of building construction, it does have some problems. In recent years, the sustainability and recyclability of this material have largely been questioned, and research to address these issues has become increasingly common in the literature.
The main factor limiting the environmental friendliness and recyclability of this material is the use of highly reactive and toxic isocyanates during its production process. Various types of catalysts and surfactants are also used to produce polyurethane foams with different properties.
It is estimated that about 30% of all recycled polyurethane foam ends up in landfill, which poses a major environmental problem for the construction industry because the material is not easily biodegradable. About a third of polyurethane foam is recycled.
There is still much to be improved in these areas, and to this end, many studies have explored new methods for recycling and reusing polyurethane foam and other polyurethane materials. Physical, chemical and biological recycling methods are commonly used to recover polyurethane foam for value-added uses.
However, there are currently no recycling options that provide a high-quality, reusable, and stable end product. Before polyurethane foam recycling can be considered a viable option for the construction and furniture industry, barriers such as cost, low productivity and a severe lack of recycling infrastructure must be addressed.
The paper, published in November 2022, explores ways to improve the sustainability and recyclability of this important building material. The study, carried out by scientists from the University of Liege in Belgium, was published in the journal Angewandte Chemie International Edition.
This innovative approach involves replacing the use of highly toxic and reactive isocyanates with more environmentally friendly materials. Carbon dioxide, another environmentally harmful chemical, is used as a raw material in this new method of producing green polyurethane foam.
This environmentally sustainable manufacturing process uses water to create the foaming agent, mimicking the foaming technology used in traditional polyurethane foam processing and successfully avoiding the use of environmentally harmful isocyanates. The end result is a green polyurethane foam that the authors call “NIPU.”
In addition to water, the process uses a catalyst to convert cyclic carbonate, a greener alternative to isocyanates, into carbon dioxide to purify the substrate. At the same time, the foam hardens by reacting with amines in the material.
The new process demonstrated in the paper allows the production of low-density solid polyurethane materials with a regular pore distribution. Chemical conversion of waste carbon dioxide provides easy access to cyclic carbonates for production processes. The result is a double action: the formation of a foaming agent and the formation of a PU matrix.
The research team has created a simple, easy-to-implement modular technology that, when combined with a readily available and inexpensive environmentally friendly starting product, creates a new generation of green polyurethane foam for the construction industry. This will therefore strengthen the industry’s efforts to achieve net-zero emissions.
While there is no one-size-fits-all approach to improving sustainability in the construction industry, research continues into different approaches to address this important environmental issue.
Innovative approaches, such as the new technology from the University of Liege team, will help significantly improve the environmental friendliness and recyclability of polyurethane foam. It is critical to replace traditional highly toxic chemicals used in recycling and improve the biodegradability of polyurethane foams.
If the construction industry is to meet its net-zero emissions commitments in line with international targets to reduce humanity’s impact on climate change and the natural world, approaches to improving circularity must be the focus of new research. Clearly, a “business as usual” approach is no longer possible.
University of Liège (2022) Developing more sustainable and recyclable polyurethane foams [Online] phys.org. acceptable:
Building with Chemistry (website) Polyurethanes in Construction [online] Buildingwithchemistry.org. acceptable:
Gadhav, R.V. et al (2019) Methods for recycling and disposal of polyurethane waste: a review of the Open Journal of Polymer Chemistry, 9 pp. 39–51 [Online] scirp.org. acceptable:
Disclaimer: The views expressed here are those of the author in his personal capacity and do not necessarily reflect the views of AZoM.com Limited T/A AZoNetwork, the owner and operator of this website. This disclaimer forms part of the terms and conditions of use of this website.
Reg Davey is a freelance writer and editor based in Nottingham, UK. Writing for AZoNetwork represents a combination of various interests and areas in which he has been interested and involved over the years, including microbiology, biomedical sciences and environmental sciences.
David, Reginald (23 May 2023). How environmentally friendly is polyurethane foam? AZoBuild. Retrieved November 22, 2023, from https://www.azobuild.com/article.aspx?ArticleID=8610.
David, Reginald: “How environmentally friendly is polyurethane foam?” AZoBuild. November 22, 2023
David, Reginald: “How environmentally friendly is polyurethane foam?” AZoBuild. https://www.azobuild.com/article.aspx?ArticleID=8610. (Accessed November 22, 2023).
David, Reginald, 2023. How Green Are Polyurethane Foams? AZoBuild, accessed November 22, 2023, https://www.azobuild.com/article.aspx?ArticleID=8610.
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Post time: Nov-22-2023
