Architects' attention absorbed by plastics
Polymers that bend but do not break
Many polymers can be found in the construction industry. They are generally selected for their considerable capacity to adapt to all types of phenomena. Some applications are particularly surprising, such as those intended to protect buildings in the event of an earthquake. Japan, which experiences several hundred earthquakes per year, leads research in this area. The first step involved understanding how the shockwave spread. In Japan, that is a science in and of itself. The country is currently considered to have the safest buildings in the world. During the dramatic magnitude nine earthquake of March 2011, not a single building collapsed. Some, such as the Tokyo Sky Tree (634 metres) swayed for a long while but held fast, like a reed facing a storm.
The explanation is simple: Japanese engineers succeeded in making their buildings elastic! And what better elastic than plastic? The buildings located in areas of high seismic activity are filled with plastics. Although various polymers are used, polyurethane, due to its strong resistance to crushing, has the lion's share. It is used in giant cushions placed in the buildings' foundations, and in wall coverings for older buildings. Finally, an Israeli engineering college has been closely studying potential improvements to buildings that do no meet the current anti-seismic standards due to their age. The researchers are attempting to develop a fibre-reinforced polymer that could be inserted into concrete block to make them elastic. There is still much secrecy surrounding developments in this area.
Polyamide to protect against rude patrons
Are electromagnetic waves harmful?The topic is a broad one, and the issue is far from being settled. This being said, some such waves can certainly be harmful to people's mental health. Who has not had the urge to strangle the owner of a mobile phone ringing in the middle of a film? Fortunately, a new composite material, when placed on a wall for instance, can absorb electromagnetic waves and therefore make them inoperative. It is a fabric composed of polyamide fibres metallised with copper and nickel. The weaving technique used is designed to absorb waves and diffuse them across the fabric's surface. The cherry on the cake is that it is almost as easy to put up as hanging wallpaper or any other floor covering. Theatre operators are not the only ones interested by this technology initially intended for defense, banks and research centres because it is also a means for preventing espionage.
Polyurethane to end noise pollution
Sound waves and the noise they make can also be a problem in certain locations. Hearing your neighbours argue can be unpleasant, and so is the permanent hubbub sometimes experienced in restaurants, for instance. There are many systems for dampening sound waves, but few of them can trap them and permanently absorb them. Among the available solutions, the most effective use foam made from polyurethane, a polymer that can take on any shape but is not particularly aesthetically-pleasing due to its black colour. Texaa, a French manufacturer, has found a workaround for this by covering it with a woven polymer. Christened Aeria, this patented envelope can withstand most anything and is very easy to clean. It has been so successful that it is now the go-to material for many architects who use it as decoration. A case of mixing business and pleasure, as it were.
The polymer was also selected to optimise the acoustics of the Dongsheng National Fitness Centre Stadium, China's largest open-roof stadium. Over 30,000 square metres of ceiling deflectors made from a honeycomb-structured melamine foam were placed on the stadium's roof. Thanks to its fine and open honeycomb structure, the foam effectively absorbs the reverberations caused by the successive reflections of sound waves on the surface of the solid structural parts made from steel and concrete. As a result, spectators enjoy greater acoustic comfort and are able to fully enjoy the events. Its considerable effectiveness is the reason for which the material is also found in recording studios and concert venues. Surprisingly, a team of architects recently decided to use it in cylindrical and cubic shapes suspended on the ceiling of a nightclub. The sound waves are absorbed, cancelling the reverberation effects that can become bothersome, even in a nightclub.
Sunburn for plastics
Moving on nfrom sound waves, the topic at hand is rays, which can be truly harmful. It has long been proven that ultra-violet (UV) rays may cause melanoma, which is why it is important to protect oneself against such rays. The message seems to have been heard looking at the number of children wearing t-shirts at the beach. This is no coincidence, since many manufacturers now sell anti-UV t-shirts. They are made from elastane and polyester fibres charged with titanium dioxide, a chemical compound that absorbs UV rays. The synthetic fibres have another advantage: they do not relax when wet and enable the t-shirt to continue providing protection.
The technique is also used in construction, and more specifically in certain blinds like the type used in offices.rThe only difference is that titanium oxide is not used, for reasons relating to rigidity, but rather fibreglass woven with PVC. The material absorbs UV rays and reflects heat, meaning that offices stay cool even during a heat wave. The blinds, which are often installed on the outside, are wear-resistant thanks to PVC, a material that is resistant to temperature variations.
The silent road is on track
Contrary to popular belief, roads are noisy not because of the vehicles' engines, but rather because of the friction of tires on the road. A particular experiment is currently underway in Denmark. A section of road was coated with a new generation material supposed to dampen the noise from tires. Decreasing the noise requires the road surface to be optimised. To do this, three parameters must be taken into account: texture, absorption and elasticity. Yet, elasticity is a parameter that had not yet been exploited. After conducting many tests in the laboratory, the Danish team successfully developed a material combining the ability to drain rainwater and adherence. This poro-elastic road surface consists of crushed rubber obtained from used car tires, crushed granite and polyurethane glue.
Although the idea of covering roads with used tires is not a new one, the materials developed to date have not been able to meet the specifications in terms of durability. Life-sized tests have been particularly conclusive as the sound level was decreased by eight decibels. This may not seem like much, but achieving a similar level of noise reduction would require building a noise-cancelling barrier almost three metres high. Silent, solid and environmentally-friendly, this type of road surfacing could soon replace noise-cancelling barriers along European motorways. That's the hope of these teams of researchers, at least.