Polyurethane Foams and Sustainability

Polyurethane Foams and Sustainability To trace the history of polyurethane, a material utilized in many applications due to its superior properties in production, we must go back to 1937. In 1937, German scientist Otto Bayer synthesized polyurethane material through the reaction of diisocyanate with diol, and this new polymer type began to be used in numerous applications thanks to the many properties it offered. Over the years, polyurethane material has developed in direct proportion to technological advances, and with the emergence of new production areas, its application areas have also expanded. As a type of polymer, polyurethane material is utilized today in many fields ranging from the automotive industry to the construction sector, from the bedding industry to the footwear industry. When looking at global PU consumption, studies conducted in the past expected PU consumption to exceed 79 billion USD by 2021. According to data from 2016, polyurethanes accounted for approximately 9% of plastic consumption. The primary consumption area for PUs is foams. (1) Polyurethane foams correspond to approximately 67% of consumption within polyurethanes. At the same time, if we look at it more broadly, PU foams occupy a significant place in the polymeric foam market, and the main reason for this is the advancement of production technology. The durability and versatility of PU foams have enabled their use in domestic and industrial applications, and even in space travel and medicine. For these reasons, the use of PU foams has risen impressively over the years. (1) If we need to classify polyurethane foams, we can divide them into two categories: flexible and rigid foams. As expanded materials, the structure of PU foams consists of a combination of various processes. The most common application area for polyurethane foams is the construction sector. Here, PU foams are utilized in the installation of doors, windows, etc. Another widely used area that provides significant benefits is sound and thermal insulation. PU foams, which can be used to fill all types of gaps, provide strong sound and thermal insulation. In the production of PU foams, most of the polyols used are obtained from petroleum raw materials. Today, due to the increasing climate crisis, the environmental impact of petroleum use, and concerns about future oil scarcity, scientists are conducting research on producing PU foams from bio and renewable materials. The adoption of sustainable methods in production and the increasing demand in this direction have led to increased use of renewable and sustainable products such as green and bio-based polyols in PU foam production. Extensive research is being conducted on the development of bio-based polyols from renewable sources such as biomass residues, vegetable oils, or industrial by-products. PU foam industry commonly uses one of the methods for more sustainable production: oxypropyation or acid liquefaction of biomass raw materials. As a result of research in this direction, it has been demonstrated that PU foams with similar properties and thermal conductivity can be produced compared to petroleum-based polyols. Work in this field is still ongoing. Apart from this method, other methods are also being used to produce more environmentally friendly PU foams. Another one of these methods is the use of vegetable oil-based polyols in PU foams. In the studies conducted, vegetable oils such as palm oil, soybean oil, canola oil, tung oil, rapeseed oil, and neem oil have been used. These oils have versatile compositions and structures, are biodegradable, and are environmentally friendly. At the same time, foams obtained from oils that dissolve in most industrial solvents exhibit good properties such as flexibility, mechanical strength, wear resistance, toughness, adhesion, chemical and corrosion resistance. For example, research has been conducted on polyurethane foams developed with polyols produced from palm oil. As a result of this research, it has been demonstrated that rigid polyurethane foams can be produced from polyols that are more environmentally friendly. (2) In addition to the use of bio-polyols, research has also been conducted on the use of crude glycerol as a polyol for producing rigid polyurethane foams. Glycerol can be obtained as a by-product of many reactions such as saponification or hydrolysis of triglycerides. The use of glycerol instead of petrochemicals in PU foam production could have a significant impact on both reducing production costs and environmental impact. Research and production continue at this point as well. Apart from these, in polyurethane foam production, alternative and more environmentally friendly methods are being used instead of petroleum-based polyols, and research in this field is continuing. The concept of sustainability has had a significant impact on consumption as well. Consumers and manufacturers who are aware of this issue prefer more environmentally friendly methods and products. At this point, major polyurethane companies in Turkey and the world are taking important steps and continuing their R&D efforts for more sustainable polyurethane foams. Sources Polyurethane Foams: Past, Present, and Future – Nuno V. Gama, Artur Ferreira, Ana Barros-Timmons Development of a Rigid Polyurethane Foam from Palm Oil – K. S. Chian, L. H. Gan Compiled by: Nilsu Kotil