Polyurethanes and sustainability

The Earth's resources are limited and it is vital that we only take what we need and do our share to protect what is left for future generations. Polyurethanes play a crucial role in preserving the natural resources of our planet. Durable polyurethane coatings ensure that the lifetime of many products is extended well beyond what would be achieved without the coating. Polyurethanes help to save energy sustainably. They help architects to better insulate buildings which reduces the consumption of gas, oil and electricity, which would otherwise be needed to heat and cool them. Thanks to polyurethanes automotive producers can design their vehicles more attractively and construct lighter frames which save on fuel consumption and emissions. Moreover, polyurethane foams used to insulate refrigerators mean that food is preserved longer and saves it from going to waste.

As well as saving energy and protecting valuable resources, there is now increased focus on ensuring that polyurethane products are not simply discarded or disposed of when they reach the end of their natural life.

Because polyurethanes are petrochemical-based polymers, it is important that we recycle them whenever possible, so that precious raw materials do not go to waste. There are various recycling options, including mechanical, chemical and feedstock recycling. Click below for further information:

Depending on the type of polyurethane, different ways of recycling can be applied, such as grinding and reuse or particle bonding. Polyurethane foam, for example, is regularly turned into carpet underlay.

If it is not recycled, the preferred option is energy recovery. Tonne for tonne, polyurethane contains the same amount of energy as coal, which makes it a very efficient feedstock for municipal incinerators that use the energy generated to heat public buildings.

The least desired option is landfill, which should be avoided wherever possible. Fortunately, this option is on the decline as governments around the world become increasingly aware of the value of waste for both recycling and energy recovery, and as countries exhaust their landfill capacity.

The polyurethane industry is also continuously innovating to produce a more sustainable material.

Find out more about the sustainability of polyurethanes.

Case studies

Polyurethane innovation in the wind power industry [ 2 February 2012]

Polyurethane innovation in the wind power industry


The European Union has set a binding target of 20 per cent of its energy supply to come from renewable sources by 2020; in order to achieve this target, more than one-third of European electrical demand will have to come from renewables. Wind power is expected to deliver 14-18 per cent of demand; delivering on these targets relies on the ever improving standards for efficiency and reliability of wind power.


One of the current challenges for the wind power industry is the weight of turbine blades. Currently, larger blades are needed to generate sufficient levels of power, however, they are also more easily damaged and harder to transport. Research teams have been racing to develop wind turbine blades which utilise the unique advantages of polyurethane.


Previously, glass reinforced polyurethane composites have been used for products including agricultural equipment, heavy-duty construction equipment and watercraft. These recent blades have adapted this polyurethane material to the specific requirements of wind turbines. The prototype blades have proven in preliminary tests to be eight times more durable, tougher and substantially lighter than conventional models such as epoxy or vinyl ester blades. The “results of mechanical testing for the carbon nanotube reinforced polyurethane show that this material outperforms currently used resins for wind blades applications,” according to Ica Manas-Zloczower, Professor of Macromolecular Science and Engineering at Case Western.

 

 

What does this all mean, you ask? The lighter, stiffer blades enabled by the usage of polyurethane allow us to maximise energy production as it permits the construction of larger wind turbines. As the blades also improve on levels of fatigue and fracture toughness, it ensures the blades ability to withstand the stress of high winds. These bigger, stronger blades in turn capture greater amounts of wind energy compared to traditional turbines. According to EWEA, “the blades should [also] be economically feasible, using sustainable materials”; the polyurethane prototype contains “low, or no, volatile organic compounds (VOCs) and use sustainable raw materials from renewable resources”. Studies on the prototype have shown that the technology “can even be “retrofitted into existing designs at minimal cost”.


The world’s total wind electricity capacity grew 50 times in the period 1990-2007 and predictions are increases over the 2008 level of 10-fold by 2030 and 20-fold by 2050. In 2009 the EU produced 163 TWh of wind power; this meant 106 million tons less of CO2, the equivalent to taking 25% of cars in the EU off the road and enough to power 82 million electric cars! Progress in the industry will inevitably be a combination of research in a variety of technical areas; polyurethane, however, provides a valuable contribution in optimising wind power technology.

Walking green: the sustainable polyurethane shoe [31 May 2011]

Recently, Bayer scientists unraveled a unique concept shoe which consists of up to 90% eco-compatible properties. The “green shoe” will bring benefits to shoe-manufacturers, consumers and in particular, to the environment.

Among these eco-compatible properties are polyurethane raw materials based on natural resources, products for solvent-free coatings and adhesives, a polycarbonate blend, and thermoplastic polyurethane based on renewable resources.

The annual environmental burden could be reduced by approximately 150.000 metric tons simply by replacing conventional solvents with new developed products and techniques for solvent- and plasticizer-free textile coatings and adhesive raw materials. 150.000 metric tons- That is more than 1% of Sweden’s annual CO2 emission.

Further, the outer and the middle soles of the “green shoe” will consist of microcellular polyurethane elastomer systems where up to 70% of renewable materials are used.

This is just another example of how manifold the application area of polyurethane is and how it can contribute to make everyday life easier and greener. Yet another example of how polyurethanes contribute to improving lives and protecting the planet in new ways every day.

From Zero to Hero: Making polyurethane from Carbon Dioxide [11 May 2011]

Reducing man-made CO2 is one of the most important priorities of our era in order to reverse climate change and avoid environmental dramas and preserve biodiversity.

CO2 is a waste gas and indeed a key contributor to climate change, and so far it was scientifically impossible to make good use of carbon dioxide, the only two options were to limit emissions or to store CO2 underground.

But after many years of intensive research, scientists have found a way to use CO2 as an alternative to petroleum as the chemical industry’s key source of the element carbon.

The biggest constraint for the industrial use of CO2 was the absence of a catalyst allowing its use as a raw material substituting petroleum. But the solution was found by Bayer and Aachen University scientists, with support from the German state and federal governments, and the CAT Catalytic Centre.

Together they were able to find a chemical precursor (catalyst) into which CO2 is incorporated and then processed into polyurethanes, which are used in thousands of everyday applications.

This important discovery led Bayer to start a pilot project and on 17 February 2011; the first plant opened in Leverkusen, Germany. The plant uses carbon dioxide from partner RWE to produce polyurethane foams.

The new process helps to boost sustainability in a number of different ways. CO2 will be used as a resource instead of being merely disposed of as waste in the future. But it may also be used as a substitute of petroleum for the chemical industry.

What’s more, polyurethanes themselves play a significant role in reducing energy consumption and protecting the climate. When used to insulate buildings from cold and heat, they can save approximately 70 times more energy than is used in their production.

This landmark scientific development is just another example of how polyurethanes contribute to improving our lives and protecting the planet in new ways every day.

New polyurethane foam gives a “green” light to green roofs [10 March 2011]

Perhaps you have already seen a garden or lawn on the roof of a building, but polyurethanes could significantly boost the current enthusiasm for green roofs, and turn urban dwellings into greener environments.

A green or “living” roof is a roof that is partially or completely covered with vegetation and a growing medium. Not only are green roofs an aesthetic pleasure, but they also possess a wide range of useful characteristics. For example, they considerably “cool down” the  building by evaporating the moist. The conventional roof absorbs and stores sunlight heat, making the building much warmer and  decreasing the frequency of air conditioner use. Data shows that green roofs can reduce cooling loads on a building by 50% to 90%  percent! Other benefits include filtering pollutants out of the air and rainwater, and improved sound insulation. It also reduces the time for storm water runoff.

Although green roofs have existed for generations, they have several installation drawbacks. The most significant is the weight of the  conventional insulation layers, such as lava stones and bulky substrates. The weight of the insulation layer increases the work and costs,  which makes green roofs a less attractive option. To solve the problem, Huntsman Polyurethanes relied on the versatile characteristics of PU; they developed the VYDRO® foam, with an aim to lower the weight of the roof layers. VYDRO® foam proved to  be an elegant solution to the weight of the roof layers. One cubic meter of lava stone weights 1500kg, while the new polyurethane foam would weigh only 30 kg for the same covered areas. The lightness of the materials means not only diminished pressure on the building,  but also the simplicity to install, reduced transportation costs and load saving of up to 70% compared to standard systems.

VYDRO® foam is certainly much lighter that conventional materials, but it is also PH-neutral; a very important factor when you have a  constant connection with water. However, what actually makes polyurethane foam exceptionally useful for green roofs is its ability to suck and store large amount of water (up to 30 times of its weight). This feature allows plants on the roof to easily access the source of water, which is vital in dry weather. So when you decide to transform your roof into the Hanging Gardens of Babylon, rely on polyurethane.

With a life expectancy of 25 years, VYDRO® foam is expected to give a huge boost to green roofs; just another example of how polyurethanes contribute to improving lives and protecting the planet in new ways every day.

Polyurethanes was key to building the house of the future: the Virginia Tech Lumenhaus [ 8 February 2011]

Have you ever wondered what houses will look like in the future? Well, you might want to ask a group of students from Virginia Tech University in the United States, who stand behind the Lumenhaus project. Inspired by the Farnsworth House by Mies Van Der Rohe, (which was build in 1951 and considered as one of finest examples of modern architecture), the students decided to create the most energy efficient and environmentally friendly pavilion today.

With support from the Virginia Tech University and a group of sponsors, they were able to write an architectural plan and soon create a prototype. Recognition came quickly - they won the European Solar Decathlon 2010 and their house has been viewed by hundreds of thousands of people.

The house itself is impressive. It uses the most environmentally and energy efficient materials available to date, combined with their excellent health and safety record. One of the materials they used was closed-cell insulation foam made from polyurethane – a regular PU foam used in our homes. The team of architects applied it in the walls and movable panels of the house.

Just like any passive house, the cornerstone to maximum savings and environmental benefits is insulation and air-tightness. Without these key elements, the potential of innovative technologies and smart construction goes to waste. As they noted, using polyurethane foam allowed tighter enclosure and significantly increased thermal resistance.

In fact, the thermal resistance of the house is five times higher than for an average house! This led to a very high energy savings rate, which has been recognised at the European  Solar Decathlon 2010 awards. In addition, the polyurethane foam they used for insulation does not contain CFCs or HCFCs.

Another striking feature is the house’s use of solar power - the rooftop photovoltaic system has the ability to vary its angle. This way it can maximize the efficiency of the power gained from the sun. Further efficient use of the sun can be found in the house’s open configuration – it has adjustable walls on the North and South side. It also features a concrete floor with a radiating heating system and contains a multitude of energy efficient appliances, all of which can be controlled with your Smartphone.

The Virginia Tech Lumenhaus project is one of the most efficient and stylish houses of 2010, and polyurethane has been an essential part of this inspiring project. Once again, just another example of how polyurethanes contribute to improving lives and protecting the planet in new ways every day.

Recycling polyurethanes in the automotive industry: Chrysler’s pioneering initiative [16 September 2010]

Can polyurethane foams be recycled? In a video posted on 27 August 2010, the American car manufacturer Chrysler shows how it has decided to swap soy-based polyurethane foams for recycled foams on the Grand Cherokee 2011’s assembly line. Chrysler announced that it was going to use 180,000 pounds of polyurethane foams that would otherwise end up in a landfill for seats and headrests.

Managing waste is as important for the environment as saving natural resources, and while soy-based foams are renewables, their creation still requires additional resources. On the other hand, recycled polyurethanes only generate so much energy as is needed to achieve the process, and Chrysler claims that it reuses all post-industrial waste that recycling generates.

Although it was an experiment, the American company is already planning on extending its polyurethane recycling practice, increasing the amount of recycled foams to 10 percent in seats and 20 percent in headrests in the future. Polyurethanes use in cars is not limited to seats and headrests, and Chrysler engineers also expressed their willingness to extend the use of Polyurethane foams everywhere possible.

Chrysler’s initiative evidences a growing concern in the car-making industry that its environmental impact is not merely limited to tailpipe emissions. And because polyurethanes are petro-chemical polymers, it is vitally important that we recycle or recover them whenever possible, to save our planet’s precious resources and keep enjoying the comfort provided by polyurethane foams in our everyday life.

There are many options available for the automotive industry to recycle or recover polyurethanes. In the video, Chrysler uses a chemical recycling process called “glycolysis” to produce regenerated polyols. To learn about the different options in detail, refer to our “Recycling and Recovering Polyurethanes” factsheet.

Chrysler’s groundbreaking initiative brilliantly echoes polyurethanes’ commitment to improving lives and protecting the planet in new ways every day.

Ecofriendly solar-powered refrigerators for Swaziland [ 9 September 2010]

Swaziland is located in Southern Africa, surrounded by South Africa and sharing a border with Mozambique. It is also one of the world’s poorest nations since over 60% of its population lives on less than 1 euro a day. About 75% of the population is employed in subsistence farming, working in dispersed villages and growing their own food. In Swaziland, food goes off quickly in high temperatures, and because electricity is not widely available, communal refrigerating appliances can only be used to a limited extent.

In light of these issues, Palfridge Ltd., a leading manufacturer of refrigerating appliances based in Swaziland, has developed an eco-friendly refrigeration solution. Using raw materials from Bayer MaterialScience, the company started manufacturing appliances with very thick-walled insulation made of rigid polyurethane foams. Used in most refrigerating appliances across the world, polyurethane foams provide outstanding insulation properties. In fact, using polyurethanes as an insulator in fridges has achieved 37% energy efficiency gains in the ten years leading to 2002.

The Palfridge appliances can keep ingredients cool up to five days without electricity, at temperatures exceeding 40°C. These appliances are also equipped with 90 Watt solar modules, which are a great help in powering refrigeration appliances in hot countries. Altogether these devices boost efficiency and consume significantly less energy than conventional refrigerators.

In a country devastated by HIV/AIDS- more than 25% of the population is infected- long-term refrigeration solutions for food and medical treatments are desperately needed, but in this case Palfridge’s appliances also make a small contribution to climate protection, by reducing emissions of gases containing fluorine to 29,000 metric tons of carbon dioxide equivalents per year.

The project was financed under the Proklima program of the Deutsche Gesellschaft für Technische Zusammebarbeit. It proves that high-performance insulation from polyurethane opens the door to the solar-powered fridge, reducing energy consumption and bringing practical solutions to some of poor countries’ most pressing problems.

Just another example of how polyurethanes contribute to improving lives and protecting the planet in new ways every day.

Polyurethanes give a shining spark to solar panels [25 August 2010]

BASF has created a new moulding system using polyurethanes, named COLO-FAST® PU, revolutionising renewable energy technology. This innovative new moulding system is used in the framing of photovoltaic (solar) panels and solar collectors and is aimed at simplifying the process as well as reducing the costs and improving standards.

Previously, the framing of solar panels and collectors was labour-intensive, involving joint cutting, bending and fastening light alloys together. However, the new framing method offered by COLO-FAST® PU, allows for all electrical connections, clasps, integrated metal plates and other installation components to be incorporated in a one-step process, making the process much quicker, cheaper and easier.

With the new COLO-FAST® PU, the polyurethane is cast directly onto the solar cell during reaction injection moulding. Reaction injection moulding is the process whereby a mixture of two parts of a polymer (in this case polyurethane) is injected into the mould under high pressure using a special mixer. The mixture is then allowed to sit in the mould long enough for it to expand and cure. At this stage, the solar cells and solar collectors are placed into a closed mould and COLO-FAST® PU is injected through a mixture head. After a reaction time of only 30 seconds, the finished framed panel can be taken out and is ready for use immediately.

Once the frame is made, the properties of polyurethane provide for the permanent protection of all components of the frame. Polyurethanes boast excellent weatherability and are highly resistant to oil, light, heat, water and chemicals, meaning the frames are well protected from damage once in place and even during transport and installation. What’s more, the frames have much greater design freedom, allowing designers to be more creative with the forms and colours, and produce light or thin frames as well.

Polyurethane is not only sustainable itself, it can also improve the sustainability of other clean technologies.

Elastogran has a new insulation technique which saves time, space and money. [25 August 2010]

In a solid construction, a typical insulated external wall has either a “double wall structure”, whereby the insulation is enclosed between two walls, or a single wall structure with additional external insulation. Both of these designs are costly and have a relatively long construction period. Elastogran avoids this complex method of insulating layers by creating an alternative – the polyurethane rigid foam Elastopor® H filling.

Elastogran’s insulation structure is made from hollow bricks which have the thermal insulation - Elastopor® H - already built into the bricks. The bricks are made from lias clay, which is formed into ceramic clay interspersed with air, and its cavity is then filled with Elastopor® H. Previously mineral wool and perlite had been used to fill hollow blocks like these, but Elastopor® H actually improves the level of insulation. What’s more, this method eliminates the need for any external insulation saving a considerable amount of space.

As well as being easier and cheaper to construct, the Elastopor® H has also proved to be more effective insulator than others that are available on the market. This is because Elastopor® H boasts the following properties:

  • Very low water absorbency – important for stable building structures;
  • No falling or trickling out of the insulation providing for a long-lasting and reliable structure;
  • Rapid cycle times allowing the rapid circulation of heat around a building – an efficient heating method;
  • Manageable investments in industrial and building systems;
  • Lower requirement for heat energy which saves energy and reduces costs and;
  • Extremely low heat conductivity.

Heat conductivity is the property of a material that indicates its ability to conduct heat. A material with low heat conductivity provides effective insulation which in turn improves the energy efficiency and the noise control within a building. Over the recent years we have witnessed a rise in energy costs – a trend which has pushed the building materials industry to focus increasingly on heat conductivity. Elastopor® H boasts extremely low heat conductivity which is why it is such an attractive alternative to other insulating materials.

The end result of Elastogran’s insulation satisfies both architects and builders alike and can be used in a wide range of applications. It is yet another example of the sustainability and comfort that polyurethane provides, while reducing heating costs and requiring little investment.

Polyurethanes composites provides outstanding thermal insulation for windows [25 August 2010]

Bayer MaterialScience has recently developed Top Therm 90 – a new concept for slimline windows and facades which has excellent insulating properties.

Top Therm 90 is made using a combination of Baytherm® polyurethane insulating foam and a thin, weather-resistant and dimensionally stable outer shell made using the Baydur® casting system. The end-product is an insulation solution which cuts heat loss by around 50% in comparison to other solutions on offer. The Baytherm foam ensures there is virtually no contact between the warm and cold sides of the frame profiles and adapts perfectly to the Baydur-casted polyurethane shell that surrounds it.

In addition, during the production of the Baytherm foam, a reaction takes place with the polyurethane, bonding the foam core permanently to the unit’s structural surfaces as it cures. This adds strength as well as optimizes the insulating properties. Baytherm allows therefore for a design with thinner walls and style, whilst still providing improved energy efficiency.

The concept is based on an integrated approach, treating the windows and frames as a single unit both in thermal and structural terms, thus optimising insulation. The process of manufacturing and installing the frame system is straightforward and thus cost-effective.

It is an ideal solution in terms of both insulation and mechanical strength, for example for windows with multiple glazing and despite having a profile thickness of just 90 millimeters, the windows still meet the necessary requirements for use in passive houses.

Making windows that meet the passive house standard; how else could polyurethane prove its key role in a sustainable future?

A solid basis for rail traffic [23 September 2008]

Railroad ties based on the glass fibre reinforced integral skin foam from Baydur® have already been in use in Japan for many years, even on high-speed Shinkansen lines. The material offers far greater durability and much lower lifecycle costs than timber and is also highly resistant to moisture.

Moreover the noise produced by streetcars/trams – the cause of numerous complaints from local residents, particularly in city centres – can be effectively dampened using the complete polyurethane rail grouting system Büfaflex®. This material, which is based on the Bayflex® system, has been developed by Polyplan GmbH, Strasslach (Germany), and the BaySystems BÜFA systems house specifically for this application and boasts a customized pore structure that literally swallows up sound.

The material is electrically non-conducting and therefore helps to prevent the corrosion damage that stray currents cause gas and water pipes, is also more cost-effective to process than conventional rail grouting systems. Rails are simply "floated" in special formwork on site and then encased in the foamed polymeric material.

Polyurethane cuts costs, decreases noise pollution and increases efficiency.

A material that is very much on track [19 August 2008]

Better dimensional and weather stability than wood, lighter than concrete Railroad builders are turning increasingly to polyurethane composite marketed under the name Eslon Neo Lumber FFU from SEKISUI CHEMICAL CO. LTD., Tokyo as the material of choice for manufacturing the ties or sleepers that are used to support railroad tracks. The material is noted for the far greater durability of the ties and the correspondingly lower lifecycle costs. In Tokyo, plastic ties have been in service for more than a quarter of a century. They have been laid, for example, under the track for the Shinkansen high-speed train, and the FFU (Fiber reinforced Foamed Urethane) polyurethane ties have now been premiered in Germany.

Railroad ties must be able to withstand high mechanical loads and must also be dimensionally stable and weather-resistant over a long period to comply with the conditions for safe rail operation and low maintenance costs. Frequent temperature changes, radiation and moisture start to affect wooden ties after a relatively short time, and repairing the wooden track involves a considerable amount of material, time, organization and cost. In comparison polyurethane ties have an estimated service life of at least 50 years. With considerably longer maintenance cycles and associated cost benefits for the railroad operator, individual ties can be replaced quickly and accurately, helping to lower construction costs even further.

The flexural strength of the polyurethane ties is also very much higher than that of wood, even after 15 years, the material is also suitable for the construction of high-speed tracks.

The polyurethane material looks like wood and combines all the positive properties of the natural product with those of a modern composite product. The polyurethane ties can be processed in the same way as timber, and compared with concrete, the polyurethane material weighs much less and boasts the reproducible evenness that is important with turnouts. The polyurethane ties are also very suitable for bridges due to their lightweight and they can be manufactured in virtually any desired length and cross-section up to a current maximum of 9.60 meters.

The ecological compatibility of the polyurethane ties is also an advantage. As a rule, ties that have already been in service can be reused, or can be recycled in the same way as the production scrap.

The polyurethane system based on long-fiber reinforced Baydur® 60 integral skin foam comes from Sumika Bayer Urethane Co., Ltd., the Japanese polyurethane systems house in Bayer MaterialScience's global BaySystems® network.

Polyurethane in railroad ties, increases durability, safety and decreases cost.

Large-format commercial vehicle bodywork parts made of polyurethane [15 February 2008]

The automotive and commercial vehicles industry is continuing to move away from sheet steel in bodywork parts and is instead using high-performance plastics. Alongside the familiar benefits of plastics such as their greater freedom of design and lower weight, their cost-effectiveness in production is also gaining in importance. Manufacturers are currently focusing their efforts on producing larger and larger parts in a single moulding process. The success achieved in this field, coupled with the possibility of integrating additional functions and components in the mould, means they can cut both costs and manufacturing time. Tailor-made polyurethane systems make it possible to produce even large mouldings with complex structures such as undercuts and ribbing in a single shot with no need for post-moulding treatment.

Furthermore the lightweight characteristics of polyurethane compared with some metal alternatives mean that vehicles are increasingly fuel efficient and therefore help reduce their impact on the environment.

Plastics make their mark in agricultural engineering

A recent example from the commercial vehicles industry involves the two side panels and tailgate of the "Jaguar Green Eye" forage harvester from Claas KGaA mbH in Harsewinkel, Germany. Each of the moulded parts is manufactured in a single shot from the flame-retardant, microcellular polyurethane system Baydur® 110 from Bayer MaterialScience supplied by the BaySystems BÜFA system house.

The excellent flow characteristics and low cavity pressure impose virtually no restrictions on the geometric design of the moulded parts, especially in the edge and interior areas.

The benefits of polyurethanes over conventional materials such as glass fibre reinforced plastics or sheet moulding compounds become particularly apparent when manufacturing large mouldings with complex interior surfaces.