The protective power of polymers

18 June 2009

The different engineered qualities of polymers – such as the ability to withstand high temperatures and corrosion – have given them a broad range of protective virtues. On land, at sea, and even in the sky, rubber is used in all shapes and forms to protect people. In industrial environments and infrastructures protection is needed from dangerous and demanding work environments, wear and tear, or the sudden and brutal forces of nature.

The protective power of polymers

On a daily basis, protective suits made of engineered fabrics coated with polymers shield professional divers, firefighters, oil-platform workers and other people at risk. Elsewhere, in such areas as retail and restaurant industries, non-slip rubber flooring prevents employees from tripping and slipping, preventing sprained ankles and broken bones. A cushioned rubber floor also protects backs and legs of employees who spend long hours on their feet.

Protective rubber is also used to enhance safety on the roads. A car’s airbag fabric shields passengers in the event of a collision, while numerous rubber seals, dampers, boots and bushings protect engines and steering systems from wear and tear. In the sky and in space, seals protect aircraft and space stations in demanding environments. And at the other extreme, deep in the ground, seismic isolation bearings installed under buildings and bridges in high-risk areas, reduce the damaging impacts of earthquakes.
There are five protective qualities displayed by such protective seals, linings, or other compensating components. They may have resistance to fire, corrosive substances, toxic gases, acids and chemicals. Or they may have durability to withstand very demanding environments. Flexibility is another quality and this is primarily found in applications that are subject to repetitive movement or forces of nature in the form of waves, wind or earth movement. Thermo insulation enables components to maintain a constant temperature (hot or cold), keeping people safe and comfortable. The final quality, diffusion resistance, prevents gas from evaporating, preventing leakage into the atmosphere.

Four Examples:

1. Bumpers that care
The first point of impact in a traffic accident involving a car and a pedestrian is usually between the bumper and the victim’s legs. The force of the impact may subsequently throw the pedestrian towards the hood of the car and the engine block. Since the engine block is a solid metal object, the outcome of this type of impact may be fatal as a result of serious head injury. Legislation is due to be introduced in 2010 to ensure that cars incorporate deflection and crumple zones to reduce head trauma. Trelleborg is already developing rubber bumpers with a metal spring that can raise the hood on impact, creating a soft zone that can prevent serious head injury.

2. Caring for the soil
Trelleborg specialises in agricultural tyres for all applications, ranging from small orchard and vineyard tractors to the latest high-powered vehicles with capacities of more than 350 hp. These days, tires are becoming more durable and stable and are able to carry heavier loads. They are also getting bigger. The larger the tire, the better its load-dispersion quality, which minimises the tire footprint left behind in the soil. This preserves the porosity of the soil so that the growth potential of the crops is protected. Tires are also developed for on and off-road safety and their self-cleaning tire profiles prevent the soiling of roads.

3. Reduced quake damage
Base isolation is a cutting-edge solution used by architects and engineers worldwide to protect buildings, bridges and other structures from the damaging effects of earthquakes. Its principle can be compared to the way a car’s suspension protects passengers from an uneven road surface, ensuring a smooth ride. Buildings and structures are supported on bearings that are rigid vertically but very soft in the horizontal direction. In an earthquake, these characteristics allow a building to move horizontally relative to the ground, reducing the damaging forces. Trelleborg’s custom engineered Andre laminated natural rubber seismic-isolation bearings have been installed under many high-risk buildings globally.

4. Sealing fire offshore
One potential hazard on board an oilrig is burning-hot oil. Polymer-based seals have proven more resistant than other forms of fire protection, such as intumescent paints or cement based coatings. Fire-penetration seals from Trelleborg Viking can withstand jet flames at more than 1,100 degrees Celsius, and are resistant enough to be in contact with burning fluids for a few hours. On board an oil platform, fire-protecting gullies made from reinforced rubber can collect and drain accidental oil spills and prevent the liquid from reaching a section where the oil could ignite.

Personal protection

Chemical protective suits are literally a matter of life or death. “Chemical protective suits are the final link in personal protective equipment, so major demands are placed on them,” said John Eklund, Product Manager for Asia at Trelleborg Protective Products. He is one of the foremost authorities in this area after 23 years in the industry.

All suits undergo comprehensive certification tests and type approval processes. The US NFPA 1991 is the toughest standard in the market.

“The standard’s minimum level is 21 chemicals plus five war agents. These have been selected to represent various groups of chemicals,” said Eklund. “Naturally, no one suit can protect against all the 10 million chemicals that are classified in the US.”

Chemical protective suits are divided into different levels. The highest, level A, protects against chemicals in liquid phase, gas forms, aerosol and in solid form. The most important properties of an A-level suit are its chemical resistance, physical strength, flexibility and flame resistance. The lowest level, D, can comprise only a visor and a pair of gloves.

“Rescue services worldwide are our predominant customer group,” said Eklund. “They have no idea what to expect at the next mission, and therefore require the most comprehensive protection. The chemical industry, however, is able to conduct a better risk assessment and can often manage with B-level suits.”

Trelleborg is still alone in the market in terms of being able to manufacture reusable and high-quality suits with only one layer, so-called single skin suits. To achieve the same protection level, competitors without this technology, use suits with different properties in double layers. “We are involved in the polymer industry and our strength lies in the fact that we can develop and manufacture our basic material within our company,” said Eklund. “Today’s trend is laminate, in which a rubberbased material is packed with a laminated plastic and a textile for strength. This combination provides a very broad protective spectrum.”

After more than 20 years in the industry, Eklund still looks forward to travelling around the world to market and sell these life-support systems. “I am an engineer, but I applied for a job in sales at Trelleborg,” he said. “As I understand it, I now have the longest experience in the industry, and I still find it interesting.”