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. Polyurethane insulation in buildings reduces the consumption of gas, oil and electricity, which would otherwise be needed to heat and cool them. Foams used to insulate refrigerators mean that food is preserved longer than would otherwise be possible.

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. Ton for ton, 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.

Find out more about the sustainability of polyurethanes.

Case studies

A solid basis for rail traffic [September 23, 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 [August 19, 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 [February 15, 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.