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Interesting facts about plastics and rubber

We come across plastics and rubber everywhere in our daily lives. Discover fascinating stories, surprising facts and interesting background information – from historical developments and well-known products to key figures and innovations in the industry.

Results (423)

  • Greater sustainability and protection of freshwater lakes

    Greater sustainability and protection of freshwater lakes In recent years, the general public has become increasingly aware of the contamination of the world’s oceans by plastic residue. The Topic of the Month article in October 2012 was devoted to this issue. It is not only the world’s oceans that are being polluted, however; freshwater systems can be contaminated by plastic particles too. A survey carried out by a research team headed by Professor Dr Christian Laforsch at Bayreuth University and Professor Dr Reinhard Niessner from Munich Technical University has drawn attention to this. There is no need to travel to remote locations when research can be carried out in the immediate vicinity instead. At Lake Garda, for example. Since it is directly below the Alps, the scientific team headed by Professor Laforsch und Professor Niessner expected to find comparatively minor pollution of the lake by plastic residue, particularly the tiniest particles known as microplastic. The research scientists were therefore very surprised by the results of their analyses: plastic particles less than 5 millimetres in size are present along the shore areas of the lake in just as high concentrations as on ocean beaches. With respect to the substances found – such as polystyrene and polyethylene - Laforsch says: “We know in the meantime that they only degrade slowly in nature if they degrade at all. This means that they contribute to ongoing contamination of ecosystems.” He also points out that the plastics involved absorb toxic organic pollutants and have the potential to take them to other, less contaminated regions. Tiny particles of polyvinyl chloride (PVC) were also detected; Laforsch says that PVC in turn can be carcinogenic, depending on how it is manufactured. Fluorescent red plastic particles in a water flea. Photo: H. Imhof / C. Laforsch, Universität Bayreuth. Risks for the food chain The scientists collected the plastic waste systematically on two Lake Garda beaches and then analysed what they found with the help of analytical methods (Raman spectroscopy and electron microscopy). In their survey, the scientists conclude that the small size of the particles increases the probability that fish, worms and other invertebrates confuse them with food. This would in turn increase the risk that toxic plastic residue finds its way into the human food chain. Photo on the left: fluorescent red plastic particles in a water flea, that have been made visible with the help of fluorescence microscopy. Water fleas feed on small algae that they ingest together with plastic particles without being able to distinguish between them. Water fleas are themselves one of the main sources of food for fish, so that plastic particles can collect in the food chain. H. Imhof / C. Laforsch, Bayreuth University. The Laforsch research team did in fact detect tiny fluorescent plastic deposits in worms, snails, clams, water fleas and ostracods. These animals are native to Lake Garda too and act as the main source of food for other animals, like fish. Lake Huron borders on the US state of Michigan and the Canadian province of Ontario. Lake Huron is 176 m above sea level and has a surface area of 59,586 square kilometres. Its maximum depth has been determined to be 229 metres. 36,351 km² are on the Canadian side of the lake, while 23,235 km² are on the US side. Plastic residue found in different concentrations It became apparent in the course of the research project that the north beach of Lake Garda is considerably more highly contaminated than the southern shore. The research scientists think that this is mainly due to the weather conditions, i.e. because the wind frequently comes out of the south-west – a phenomenon that the locals call “Ora”. The scientists point out that a team of Canadian research scientists reported on comparable findings two years before at Lake Huron, through which the American-Canadian border runs. 94 per cent of the plastic particles found at Lake Huron were in a single shore area. Contaminated freshwater lakes are not uncommon. Consequences for ecology and environmental policy The obvious question in this context is: where does the plastic waste come from that contaminates some of the beaches on Lake Garda? It appears to be the case that a large proportion is accounted for by consumer goods and packaging materials, that reach the lake and thus the areas close to the shores either directly or indirectly via landfill sites. According to Professor Laforsch from the Animal Ecology Faculty at Bayreuth University, Lake Garda is by no means an unusual example of the contamination of an ecosystem by plastics. The opposite seems to be the case: Since the location of the lake at the foot of the Alps means that there are comparatively few environmental risks, the two research scientists suspect that freshwater ecosystems closer to urban centres and industrial facilities are affected much more strongly. “We would like the results of the analyses that we have published in ‘Current Biology’ to be understood as a general warning signal”, says Professor Laforsch. He emphasises that plastic residue is a danger that is not by any means restricted to remote oceanic regions, such as the well-known Great Pacific Garbage Patch. The environmental scientific and political communities should show greater interest in this problem. Collection of various plastic particles that were picked up on the shores of Lake Garda. Many of these particles, especially some highly toxic substances, however, are so tiny (less than 500 microns) that they are not visible with the naked eye. Interdisciplinary research project funded by the German Research Foundation The case study that has just been published is the result of the project funded by the German Research Foundation (DFG) entitled “Plastic particles in limnic ecosystems: distribution and impact on aquatic organisms”. The aim of the project is to investigate the plastic pollution of selected German and European lakes and rivers with the help of Raman microspectroscopy (RM). A particular focus here is the issue of how plastic particles are distributed in the lakes and rivers. The project partners also want to find out in what form and quantities plastic particles collect in organisms and organs. The project will therefore help to identify the risks associated with the contamination of ecosystems by plastic residue. It can in this way contribute to the development of strategies for the avoidance of harm to people and nature in future. Handling valuable plastic materials correctly is an important step: experts too are convinced that they do not belong in the environment or on landfill sites. It is essential that we adopt recycling as our approach. Plastic is too valuable for it to be disposed of simply by dumping it in the environment. Source H. K. Imhof, N. P. Ivleva, J. Schmid, R. Niessner, C. Laforsch, Contamination of beach sediments of a subalpine lake with microplastic particles, Current Biology 23 (2013) 867-868

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  • Washing machine gaskets: absolutely no leakage and permanently elastic

    In a four-person family, the washing machine is in operation about one-and-a-half hours a day. On average, it washes, rinses and spins about 250 times a year, cleaning some 1,000 kilograms of dirty washing – an amount that is increasing all the time. Its components – particularly the rubber hose systems and rubber gaskets – are subjected to greater chemical and mechanical stresses than just about any other household appliance. All the sealing property and stability requirements can, however, be satisfied, thanks to universal, resistant ethylene propylene diene monomer (EPDM) rubber. Elastomer research is helping to make sure this remains the case. Countless litres of water and various washing solutions flow through a washing machine over the years. In addition to washing effectively enough, this household appliance has to do one thing more than anything else: it must not leak. Hose systems and gaskets should not go brittle and should definitely not tear suddenly. Moisture, detergents and cleaning agents – particularly alkaline agents – as well as high water temperatures must not have an adverse effect on the material: this is the requirement profile compiled by experts from, for example, well-known manufacturers of household appliances. On the assumption that white goods of this kind have a useful life of ten or twenty years, this also means that all the rubber parts have to last this long too – that at least is the theoretical plan. However one looks at it: the elastomers used therefore need to be extremely hard-wearing and resist ageing very effectively. Rubber experts are convinced that synthetic rubber made from EPDM complies with the strict standards made by washing machine manufacturers in every respect. It remains completely leakproof, is particularly elastic and abrasion-resistant and does not discolour. Another advantage when it is used in washing machines: this synthetic rubber only swells minimally even under the most unfavourable of conditions and resists aqueous solutions of detergents, fabric softeners and other laundry treatment agents for a long period of time at washing temperatures of 95 degrees Celsius. Parts moulded from EPDM are the preferred choice where exacting demands are made on the elasticity of the components. Although the door sealing ring of a washing machine is expected to keep the washing water in, for example, it is also supposed as far as is possible to behave as if it was not even there. This means that the material used has, on the one hand, to be stable enough to enable the sealing ring to be attached not only to the washing machine housing but also to the suds container. On the other hand, however, it is supposed to be extremely elastic, so that it does not transfer the forces produced during the spinning cycle from the rotating suds container to the housing. Otherwise the washing machine would not stay still when in operation; it would move around instead, as washing machine experts emphasise. The mechanical stresses to which a door sealing ring is exposed depend in the final analysis on the displacement of the suds container that is attributable to imbalance during the spinning cycle. This occurs in washing machines when the laundry is distributed unevenly in the drum – collecting inside a pillow in the extremest of cases. This prevents consistent rotation. Imbalance can never be avoided entirely, so manufacturers always include specific displacement tolerance when designing their appliances. A force that produces a weight of ten kilograms acts on the door sealing ring in this context. EPDM can cope with this tensile force without any difficulty. However: EPDM door sealing rings are not immune to objects with pointed ends or sharp edges that can get into the washing machine via trouser pockets, for example: a nail, a screw or a hairpin can destroy them. EPDM does have high tear propagation resistance properties, on the other hand. In other words: the door sealing ring is generally stable to a certain extent in spite of a hole and drum movement. Although flooding of the washing machine location is not an immediate risk, the gasket definitely needs to be replaced. Modern, fully automatic washing machines also have special safety systems for such cases. GDeußing More informationen about ethylen propylen dien rubber (EPDM)

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  • Adding precision to plastics testing

    The test piece’s special shape permits substantially more realistic testing scenarios for plastic components. Plastics play an important role in many consumer items. But testing precisely how much load these plastic parts can bear has up to now been a very complicated task. Now, a new instrument achieves simpler and more accurate measurements. So that relaxed Sunday outing came to nothing. The car broke down after just a few kilometers. Why? Because a tiny crack in the gasoline pump brought the engine to a standstill. An operating life of several thousand hours proved to be too much for the plastic component to take. To keep occurrences of this kind rare, specialists regularly put important plastic components to the test. As a material, plastic’s importance goes way beyond cars: it’s plastic that keeps our washing machines running, makes sure the coffee that comes out of the machine tastes good, keeps our drainpipes clean, and guarantees that insulating materials don’t fail – among many, many other applications. There’s just about no end to where plastics are used. Given that every component reacts completely differently to stresses, it’s a tricky business to obtain exact test results. In an effort to keep the workload down to a manageable level, researchers get representative results from a test piece made using the same material, as opposed to testing individual components. Dominik Spancken of the Fraunhofer Institute for Structural Durability and System Reliability LBF in Darmstadt describes the typical approach: “Generally our customer provides us with a certain quantity of plastic granulate, which is the base material for plastic products. We use this granulate to create test pieces and subject these to various loads. Our computers record the values and calculate a lifecycle model for each material.” The drawback with this approach is that researchers can only ever study one spatial load at a time, for instance pressure or strain at a single point. But in fact plastic components are mostly subjected to loads along multiple axes – in other words, they are maltreated from all sides. “That’s why measurements were often just an approximation,” says Spancken of this dilemma. Water pressure simulates loads The most realistic way to simulate the loads that plastics are subjected to is with the internal pressure process. This uses a special piece of equipment to press a fluid medium – perhaps water, oil or brine – against the walls of the test piece from within. This simulates an even distribution of pressure. The problem is it wasn’t possible to apply this process with the equipment available up to now when the test pieces were solid. So the researchers had to redesign the test piece, the process and the testing equipment. And the result is the MultiTester, a hollow thermoplastic object that looks a little like a bell jar you might put over cheese. Straightforward to produce by injection molding, it can easily be adjusted to a wide range of test scenarios. Wall thickness, environmental influences and load types can for instance all be set to any desired value. What is more, the scientists can determine the degree of influence that reinforcing fibers have. “These special materials can usually cope with double the pressure,” describes Spancken.

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  • Polymer materials are very versatile, but can they do everything?

    The k-online editorial staff were struck by a recent dpa report. Although we were, on the one hand, delighted to see how much faith people have in plastics, we were, on the other hand, concerned by how thoughtlessly the material is used. The Deutsche Presseagentur published the following report at the beginning of July: a 46-year-old man had been driving a car through Hückeswagen in North Rhine-Westphalia in Germany using a plastic bucket as a seat. The bucket tipped over, the man lost control of his car and ran into a parked car. When the police arrived, they were astonished to find that the man had not just replaced the driver’s seat by a plastic bucket; apart from that, there was nothing else inside the car. It goes without saying that plastics simply are more interesting, more functional and – in a nutshell – better than conventional materials in many applications. Plastics are compositions that can be created from the inside to the outside to meet customised needs. They can be flexible or rigid, extremely soft or impact-resistant. They can withstand pressure levels at which other materials would burst and they can be manufactured at lower cost in most cases too. In addition to this, plastics can be produced to have practically any shape – an advantage that designers in particular appreciate. All in all: depending on the requirements and the application, plastics are often the more attractive alternative – on one condition: when they are designed, produced and used to satisfy the demands of specific applications. Which brings us back to the press report: Plastic buckets are designed to collect, store and transport liquid and free-flowing materials. You can make music with it and plastic buckets is also a very helpful thing in clean-up house and car. If there are no other options, it is possible to sit on an empty bucket after it has been turned upside down. When nothing else is available to sit on and the floor is soaking wet, there is no doubt that a plastic bucket is a most welcome seat, even though the bottom of a bucket is not designed to support the bottom of a human being. Not to mention the fact that it is difficult not to look rather foolish squatting on such a makeshift seat. Under no circumstances whatsoever, however, should even the greatest of plastic lovers use a plastic bucket as a car seat. Not only because it is so uncomfortable and there are more than enough plastic-based car seats with all sorts of ingenious extras. But also because the classic plastic bucket does not have the vital safety features: a back and head rest and facilities to attach a seat belt. Or is someone somewhere cooking up plans for this, perhaps? After all, it is a well-known fact that there is no end to the creativity of polymer materials and the people who work with them. GDeußing

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  • Polymer materials are the future:

    Modern cars consist to a large extent of plastic. More than 2,000 components are polymer-based. The situation was completely different when the automotive age began. The first cars were iron-based and very heavy – wood was only used here and there. One polymer material has been involved right from the start, however: rubber. It is a fair question: would the car industry have become what it is today if ingenious engineers and polymer experts – particularly John Boyd Dunlop (1841-1921) – had not made crucial progress in the development of pneumatic tyres? The Oldtimer Grand Prix, which is being held by the German Automobile Club (AvD) at the Nürburgring Race Track from 9. to 11. August 2013, is a good opportunity to look back at the historical moments in the automotive age. Just for the sake of complete accuracy, it should be mentioned that the Scot Robert William Thomson invented the pneumatic tyre as early as 1845. This tyre consisted of one or more canvas tubes that were impregnated with rubber and covered with leather. He was way ahead of his time with his invention, however; not even bicycles that needed pneumatic tyres existed back then. Some vehicles did at least run on Thomson tyres too later on: some of them had several different chambers (tubes) for the air and were to a certain extent the predecessors of a number of designs for puncture-resistant tyres. Pneumatic tyres were put to a long-distance test seven years after John Boyd Dunlop obtained a patent for air-filled tyres – in 1895. The brothers André and Edouard Michelin chose these tyres for the Paris-Bordeaux-Paris car race, in which they participated with a Peugeot car known as “Eclair” (lightning). They did not prove to be much of a help, however, because they did not finish the race in first place; on the contrary, they only just managed to finish at all: they suffered 50 breakdowns and had to change the tyres 22 times in what were sometimes laborious operations. The winner – Emil Layassor – did not face the same problems: he opted for solid rubber tyres. Although this was a major defeat for the Michelin brothers personally, it did not have any adverse effect on tyre development. In fact, things really started to get going after this. The first cars with pneumatic tyres were already being supplied directly from the factory only three years later. Continental included car tyres in its range for the first time in 1899 too. Price: 269 marks, useful life: 500 kilometres. In the same year, the Belgian Camille Jenatzy reached a speed of more than 100 km/h – an incredible feat at the time – with an electric vehicle and special pneumatic tyres supplied by Michelin. Ultrafast driving normally started at only 20 km/h at this time, because the maximum possible speed was generally around 15 km/h. Appearances are important Tyre design changed around 1904: they were given more distinctive tread, while they became less colourful at the same time. Tread with cross ribbing was where the future lay. The addition of carbon black – which is standard procedure to this day – increased the strength of the rubber, which in the final analysis led to a longer useful life. Whereas they tended to be yellowy-white before, tyres were now black. There were other important stages in the development of tyres to what they are today, however: they quite literally took to the air in 1915, when Pirelli manufactured the first pneumatic tyres for aircraft. Two years later, Goodyear produced the first pneumatic lorry tyres and Bayer introduced synthetic rubber for the first time, which was a major step forward for the tyre industry. Another decisive change was made to pneumatic tyres in 1922: at the International Motor Show (IAA), Dunlop presented the first car tyre with steel wire in the bead, so that it fitted better on the rim – something that has been standard in production since 1924. We now jump to 1943: patents are filed in quick succession. Continental obtains one for tubeless tyres – a standard feature nowadays – while Michelin is granted one three years later for steel-belted tyres. In 1950, two letters caused a sensation in the tyre community: M+S. Although the first mud + snow tyres had deep tread and were loud, they performed better than other tyres in wintry road conditions. It was not until 30 years later that Goodyear presented the first genuinely all-season tyre. This tyre was a very sensible solution for people who did not buy winter tyres, as it was suitable for all weather conditions. Like its successors, it was identified by M+S lettering on the side of the tyre. Car tyres made from dandelions and soy An in-depth description of what happened after this can be found in one of our Topics of the Month “Tyres, tyres, tyres – how it all began”. For the sake of complete accuracy – once again – another facet needs to be added at this point. It is based on information that originated in 2010 and was recently supplemented by further details relating to timing. For a number of years now, Goodyear has been focussing intensively on the development of a tyre made from renewable biomass. For familiar reasons: mineral oil, which has been the main raw material used in the production of synthetic rubber up to now, is a resource that is unfortunately only available in finite amounts and is too precious to be used for heating purposes or to be worn off on roads around the world. The tyre industry, which – according to a report in the online edition of the German news magazine Spiegel - has arrived in the post-petrochemical age, has realised this too. Its motto is: back to the roots, i.e. the tyres of the future will be supplied by Mother Nature again. That is the plan, the noble aim. Natural rubber is only playing a minor role in this context, however. The plants that the scientists intend to harvest in order to manufacture car tyres are much smaller. What are involved here are extracts of dandelion or soy oil. Whereas Continental is still reluctant to issue any specific statements about when it plans to introduce an “environmentally sound” car tyre, Bridgestone’s message is very clear; it has announced that it will be launching natural tyres in 2020 which will have a comparable property profile (i.e. rolling resistance, braking characteristics and road grip) to conventional tyres. The American company Goodyear is stepping on the gas more than this: together with DuPont Industrial Biosciences, the US tyre manufacturer is working on the development of biobased isoprene, from which rubber can also be produced - without mineral oil. Current tests have evidently raised the company’s expectations, so that it anticipates the introduction of such new environmentally sound tyres in 2015. k-online wishes everyone involved great success in this project. GDeußing

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  • Polymers are conquering the bathroom: wellness instead of drab sanitaryware

    For a long time, designers had to make do with such conventional materials as steel and ceramics when planning bathrooms and kitchens. Times have changed: plastics provide the basis for new shapes and a new concept of well-being. For a long time, designers had to make do with such conventional materials as steel and ceramics when planning bathrooms and kitchens. In the past, composite materials have been the only alternative for sanitaryware. They are produced by the gelcoating or solid surface process and have distinct restrictions as far as haptic, gloss, scratch resistance and other performance characteristics are concerned. The results look sound, but there are limits to their resistance and creative potential. Not because there is a lack of ideas. The conventional materials simply leave too much to be desired as regards design, functionality and colour. Modern bathrooms clamour for new materials, on the other hand, with which contemporary designs and future trends can be implemented. They can, however, only be produced with the help of versatile polymer material combinations. Material combinations known as composites of the kind used in bathrooms and toilets are not only more versatile at the design level; they also have a property profile that stainless steel and ceramics could never imagine - if they even had the ability to do so. Thanks to special additives, composites can be designed to fulfil any individual wishes or ideas as to their shape, colour and haptic properties; in addition to this, they are three to four times as abrasion-resistant and very much more scratch-resistant than standard surface and gelcoat materials. This means that they are particularly suitable for bathrooms that are in constant use, such as those in public buildings. Composites offer considerable added value: designers are enthusiastic about this material, because it gives them plenty of creative freedom. Sanitaryware made from this material has warm and pleasant haptic properties too - they do not feel like plastic at all. Larger objects like bathtubs and washbasins up to four metres long can be also be made from them. And there is a new development: customised production is possible with this material, including the integration on request of screw connections or jets of the kind required, for example, for hot tubs and whirlpools. The sanitaryware is simple to clean and just as easy to repair, if this becomes necessary. In a nutshell: modern composites turn drab bathrooms into relaxing wellness oases. GDeußing

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  • Polymers used in a covert operation:

    When things get really exciting on a film set and the scene is too dangerous for the leading actor, the doubles and the stuntmen take over. It is their job to play with fire, to leap from enormous heights, to drive down a steep road towards a ravine in a car with no brakes. The only security the driver has: the parachute hidden under his shirt, where it cannot be seen by the audience, and his past experience, on the basis of which he tackles even such a difficult mission successfully. At the end, when the car plunges over the edge of the ravine, he can only hope that the car door doesn’t stick. A museum, on the other hand, is not a film set and it is certainly not a place where there is tremendous danger – at least danger of the kind that requires a stuntman. However, the German press only recently reported about a case that demonstrates how important it can be to use a double even in a museum environment, in order to protect valuable exhibits against damage. This is what happened: Some nimble thieves who were not, however, material experts obtained illegal access to the König Museum in Bonn in a cloak-and-dagger operation. They were aiming for a mockup of the African savannas or, more precisely: a stuffed rhinoceros, because they planned to steal its horn and sell it at a hefty profit. As the media reported, the reason for this was the fact that one kilogram of horn was supposed to net them about € 50,000 on the black market. In Eastern Asia, it is said that this part of the rhinoceros’ body, which is rare on the free market otherwise because it is protected, gets temperatures down and allegedly increases sexual potency – as is already indicated by the shape of the horn – when it is ground into powder. Since the white rhinoceros, which is an extremely impressive creature that is not exactly harmless in the wild, had of course already died and been stuffed before reaching the museum, the thieves thought that it would be easy prey. What they did not know, however, was that the museum – in contrast to the thieves – had taken preventive measures in advance to provide protection against a possible theft. Some time ago, the genuine horn had already been cut off the rhinoceros’ body and stored in a safe, while it was replaced by a plastic substitute. It appears that the plastic horn looked so convincingly genuine that the thieves never guessed that it was a substitute. Not even when they started to cut it off with a saw. Congratulations to the plastic; no double could have done its job better. Incidentally: it is in actual fact a pity that the thieves were caught. Because it would have been interesting to find out what effect the powder obtained from the plastic horn and used for medicinal purposes would have had. The doctor and the patient would probably not have noticed the difference – or would they? After all, experience has shown that plastics have already replaced other materials in an effective and sustained way in many application areas. GDeußing

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  • Polymers make sure that justice is done

    In most cases, reality is more complicated than fiction: it is not unusual for the police and public prosecutors to have to tackle the difficult assignment of finding out exactly how a corpse suffered gunshot wounds. A tremendous amount of forensic skill is needed to determine as certainly as possible whether a murder or a suicide has occurred. Such skill alone is not enough on some occasions, however – without suitable instruments and materials: polymer materials, for example, can be extremely helpful when evidence needs to be collected after firearms have been used and the circumstances of a crime have to be determined. As far as the police were concerned, the case seemed to be clear: after they had gone on a pub crawl together, Peter G. had shot and killed his mate Helmut S. at point blank range. The evidence indicated this. Peter G., however, insisted over and over again that he was innocent and claimed that S. had killed himself. The investigators didn’t believe a word he said, on the other hand. Because there was gunshot residue on Peter G.’s right hand, whereas none was found on the hands of the dead man. The policemen were therefore convinced that Peter G. had fired the fatal shot at his mate. Gunshot residue is microscopically small and can be found on the weapon and the hand of the person who shot the weapon. The composition of the residue depends on the type of ammunition and contains, for example, lead, barium and antimony; these substances form a film on the surface of the skin that is not visible to the naked eye. Every weapon leaves very typical residue behind when a shot is fired, so that the perpetrator is brandmarked, as it were: it is practically impossible to remove the residue even if the hands are washed intensively with water and soap; it can still be found even days after the event. The police can use gunshot residue to find the true culprit – but only if the appropriate method is used to collect the evidence. And there is a whole range of different methods: in most cases, the police use moist cotton swabs or strips of adhesive tape to take random samples in order to find gunshot residue on the hand of the suspect. The advantage of both these methods is that they can be carried out quickly on the scene of the crime. Their disadvantage is their inaccuracy: they do not allow any definite conclusions to be drawn about whether a suspect really has shot with a specific firearm, as the prominent forensic pathologist and acknowledged shooting expert Professor Christian Schyma from the Forensic Pathology Institute at Bern University explains: “Mere contact with a firearm already leads to gunshot residue being left on the hand – i.e. even without the firearm being shot.” As opposed to this, the distribution of the gunshot residue on the thumb, the index finger and the back of the hand reveal very much more about the circumstances of the crime. Schyma: “The shooting hand can be determined definitely on the basis of the density of the residue.” In the best process that is available at the present time to collect gunshot residue, the hand is covered with liquid plastic known as polyvinyl alcohol (PVAL). As soon as the plastic has set, it can be pulled off like a rubber glove. Even minute residue on the surface of the skin, such as blood, gunshot residue, fibres and other particles, are preserved in it, so they can be examined and precisely localised under a microscope. Serological analyses are possible with the evidence collected in this way too: “We can obtain DNA from blood and tissue that sticks to the plastic and can make a genetic fingerprint of the criminal”, Schyma says. When the conventional methods are used, it is normally the case that one type of evidence is lost – either gunshot residue or blood / tissue. Many cases in which the criminal was unclear at first have been solved with the help of the PVAL glove – including controversial suicides. Because tiny but typical traces of one’s own tissue stick to the hand of the person who has fired the shot in suicide cases. They are easy to collect, examine and attribute with the PVAL method. If the investigators had used this method, shooting expert Schyma is convinced that the speculation which developed – for example – after the fatal police mission in Bad Kleinen in 1993 would have been eliminated before it even started. With the help of the PVAL glove, it would have been possible to determine without any doubt whether the former Red Army Faction member Wolfgang Grams committed suicide at the time or was shot by a member of the GSG 9 special operations team. Back to the case of Peter G. Since he continued to protest his innocence vehemently even after two days of intensive interrogation, the PVAL method was, finally, used on the dead man Helmut S.: and the gunshot residue on his right hand really was found to be distributed in the typical way that could not be determined with the conventional methods. So S. did fire the fatal shot himself. G. had simply held the gun in his hand once for a short time. The truth was uncovered – thanks to plastic. GDeußing

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  • Game, set and match: advantage plastic

    Professional tennis players appreciate artificial grass courts: they are safer for the players themselves, while they are easier for groundskeepers to look after. While artificial turf pitches with underground heating enable football players to play their game at a consistently high level all year round too. New York, September 2011. The heavens did not mean well with the players at the US Open Tennis Tournament. It poured with rain and the Center Court became dangerously slippery. Puddles formed on the hard courts and it was difficult for the players to find their rhythm because of the constant interruptions. The groundskeepers made desperate use of the plastic tarpaulins to cover the courts. Rain can cause considerable problems with the surface of a tennis court, whether it is a hard court, a grass court or a complexly structured clay court. Each of these surfaces has at least one special feature that tennis players have to come to terms with: it is a well-known fact that balls move fast on hard courts. They bounce extremely high on grass courts cut short and generously irrigated the English way, so that serve-and-volley specialists and players who like to come to the net love these courts. Reddish-orange clay courts, on the other hand, consist of crushed bricks and are considered to be slow, sensitive to changes in the weather and unpredictable, while they also require intensive care. They are loved by many tennis players even so, because they can “slide into” the balls during the games, which eases the strain on their joints. Everyone has to watch out when it starts to rain, however ... Modern tennis court surfaces made from artificial grass are not affected by the elements, while they at the same time provide players with consistently optimum conditions all year round. The artificial grass surfaces that are available nowadays for tennis courts or golf courses are high-tech products that are designed to satisfy the most exacting of demands. Although not all artificial grass is the same ... Let us take a closer look at what exactly is involved here: artificial grass is a system that consists of a textile layer - profiled blades made from the plastic polypropylene - woven into a synthetic fabric web and bonded with a stable substructure. How well artificial grass works depends primarily on the filler material in which the polymer blades are embedded. The conventional filler that is used is sand, that neither allows rainwater to soak through quickly nor guarantees a good, long-term playing surface because of its consistently small, densely packed particles. Both of these parameters can be influenced positively when a filler is used that has particles of varying size, such as quartz crystals containing silicon oxide, surrounded by a glass-ceramic layer coloured in accordance with individual preferences. This material is highly porous and has optimum permeability with respect to rainwater. The edges of the particles are rounded off too; the plastic blades of grass in them do not buckle irreversibly even under tremendous stress; they return to their upright position, ready to let the ball bounce off at the appropriate angle and with the necessary spin. From the point of view of sport physiology, this is an optimum surface on which balls bounce perfectly. Players love it – and so do groundskeepers: the artificial grass is already dry and ready to be played on again completely normally again only a short time after it has rained; tarpaulins are no longer needed to cover the courts and the surface only has to be replaced by the groundskeeper every five to ten years instead of every year. Everyone is impressed by this – not only Grand Slam tournament venues but also the local tennis club round the corner. Talking about round the corner: the plastics trade fair hopes that Fortuna Düsseldorf enjoys its new artificial grass pitches in future. Thanks to the heating system underneath the grass, they can be played on fully effectively all year round, even when the ground temperature is below freezing everywhere else. 40,000 metres of plastic piping were, in total, laid for this grass heating system, by the way. Further evidence of the fact that there is practically no alternative to polymer materials as far as functionality and cost effectiveness are concerned. GDeußing

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  • Quantum Light from Diamond and Plastic

    Science knows no boundaries when it comes to developing new materials. Researchers have recently created and celebrated an especially precious material compound: an eternal union of diamond and plastic under laser light. Researchers from Humboldt-Universität zu Berlin and Karlsruhe Institute for Technology (KIT) have developed a simple method to fabricate stable sources of single light quanta. The approach published in the Open Access Journal Scientific Reports of Nature Publishing Group is based on a novel hybrid approach combining two completely different material systems. On the one side, there are tiny fragments of diamond. Besides carbon diamond contains other atoms as natural impurities. These impurity atoms or so-called colour centres are responsible for the yellow or blue colours of natural diamond. Due to their very small size of only a few millionths of a millimetre, some of the diamond fragments contained only a single colour centre, which could be excited optically with the help of laser light. The colour centre releases its energy by emission of single quanta of light, or photons, which are thus generated in a controlled way one-by-one. The researchers now mixed the diamond fragments with a special photo resist. A focussed laser beam irradiating the resist layer induced local polymerisation, i.e. the resist was turned into plastic. In this way it was possible to write nearly arbitrary three-dimensional structures, which contain single diamond fragments with single colour centres. The research team at first fabricated optical waveguides and resonators for efficient collection and routing of the photons emitted from the colour centres. A major advantage of the new hybrid material system is on the one hand the well-established and cost efficient fabrication method and on the other hand the unlimited stability of operation even at room temperature. The next steps are now to combine the novel structures with other optical instrumentation. The researchers expect that in this way numerous applications in the fields of high-resolution microscopy, optical sensing, or quantum information processing can be realized in a reliable and cost-efficient approach. GD Further information: A. W. Schell, J. Kaschke, J. Fischer, R. Henze, J. Wolters, M. Wegener, O. Benson, Scientific Reports 3:1577, 1-5 (2013)

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  • Apropos K

    Any handyman who deserves the name has them in his toolbox: polymer products like adhesive tape and cable ties. You never know when you may need them – and what for. It is important for them to be available when they are required fast. In no time at all, cracks are closed, holes are covered up, hoses are clamped and cables are laid. Very quickly – thanks to adhesive tape and cable ties. The crew of an Iceland Air plane that was flying from Iceland to New York discovered last month that both of these products can prove to be extremely useful even on board a passenger jet. What do you do when you think the flight from Reykjavik to your job in the Caribbean via New York is too long? Some frequent flyers suggest drinking one or two small but highly alcoholic drinks and then sleeping the whole of the flight. An engineer from Iceland appears to have misunderstood this advice: instead of drinking just a few glasses, he polished off an entire bottle of alcohol (and perhaps even more) that he had bought in the duty-free shop before boarding the plane. As soon as the plane was in the air, the Icelander started drinking again, but this did not put him to sleep. He started to cause a commotion instead. He was so drunk that he insulted the cabin staff and other passengers and went on the rampage. Flight safety was jeopardised, so some men from South America decided to take action: they overwhelmed the troublemaker, took him back to his seat, tied him up to it like a well-packaged parcel using adhesive tape and cable ties – and gagged him. The police were waiting for the drunkard when the plane arrived in New York, where he was arrested and taken to a hospital to sober up. We have not received any official confirmation from the airline, but it can be safely assumed that Iceland Air has added an extra point to the checklist for its planes: they are only allowed to take off if adhesive tape and plastic cable ties are on board. An example that others are certain to follow. Guido Deußing

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  • Diving fun thanks to plastics

    Millions of people explore the oceans every year with diving goggles and a snorkel, a lot of them prefer technical equipment and compressed air for their underwater trips. Diving is such a fascinating sport that it is easy for beginners to overlook the fact that although air is the most important thing divers need to survive underwater it is not the only thing. They also need to be in good physical condition and wrap themselves in outer packaging that is appropriate for the water temperature. The types of equipment that are available for recreational divers today can be viewed for example at the “ Boot ” exhibit from 19th to 27th January 2013. This exhibit shows: diving without plastics is unthinkable. One of the characteristics of water is that it removes heat from an unprotected body within a very short time – about 25 times faster than air is able to do this. What is a simple physical law can under some circumstances represent the start of a catastrophe for a diver: hypothermia causes circulation problems, which can in turn have the effect that the diver falls completely unconscious - with fatal consequences underwater. Wearing a diving suit helps to reduce the risk. Impressions of the boot 2013 Safe clothing for divers Most diving enthusiasts opt for diving suits made from chloroprene rubber because of their excellent insulation properties; the finished product made from the plastic is better known to many as a neoprene suit. In contrast to clothes made from neoprene, fashion plays only a minor role when buying a diving suit. Dass es aber auch chic und schön geht, zeigt die boot 2013. Fashionable chic is nevertheless possible, as demonstrated at the Boot 2013 (www.boot.de) Functional efficiency is the priority A distinction is made between dry, semi-dry and wet diving suits, depending on whether and how much water can penetrate between the surface of the body and the inside of the suit. While a dry diving suit provides sufficient space for warm underwear, a wet or semi-dry diving suit should fit perfectly - quite literally like a second skin. For a good reason: Water stores heat or: when wrinkles make you feel cold Water that is located in the space between the surface of the body and the inside of the diving suit is warmed up by the heat of the body and helps to store heat underwater. In order to make sure that the impact of this heating process is not reduced, the water should not if at all possible circulate and mix with the water outside while diving. Impressions of the boot 2013 Problems occur when wrinkles form in the suit. More water than is supposed to gets into the space between the body and the suit. Logically enough, this in turn means that the body has to increase its heating output in order to keep the water at the same temperature: it cools down faster and the diver feels cold - in spite of the suit. The thicker the better? With diving suits this is relative It is not only important for the diving suit to fit properly. Herbert Seelig, a rubber engineer and process chemist at Sedo Chemicals, says that the quality of the material used primarily determines the heat protection that is provided. This company from Fürstenwalde by the River Spree in Germany is the leading European supplier of chloroprene rubber, which it has for years now been processing into panels from which high-quality diving suits are produced; about ten companies operate in this field around the world. A cross section of one of the breathable chloroprene panels confirms Seelig's statement: countless tiny bubbles filled with nitrogen and water vapour are located next to each other in the vulcanised chloroprene rubber; vulcanisation means using suitable processes to change the material from a mainly plastic state to an elastic state. The bubbles protect the diver against heat loss – like double-glazed windows, if you like. The smaller their diameter, the more bubbles there are and the better the insulation. Impressions of the boot 2013 Seelig says that the production process has a crucial effect on the size and consistency of the gas bubbles in the finished product. He mixes the ingredients like a baker who is preparing to make a delicious cake by a secret old family recipe. He kneads the chloroprene dough, feeling and examining it. Over and over again. And in the same way that dough made with yeast is given time to rise, the rubber material has to be allowed to "rest". During this time, gas bubbles form that are distributed throughout the material and guarantee optimum heat protection after the material has been vulcanised and the diving suit has been cut out. Quality has its price Chloroprene rubber occasionally costs substantially more than high-quality leather. In order to reduce the price, some suppliers use cheap fillers which have a negative effect on the functionality and useful life of a diving suit. An example: at a depth of about 20 metres, the pressure of the water compresses what can be described as "airy" chloroprene seven millimetres thick so that it is only about three to four millimetres thick afterwards. The gas bubbles are very good at resisting compression here: they maintain their density and position and thus their insulation properties in spite of the pressure. Compact fillers, on the other hand, reduce their thickness under pressure: they get thinner and thinner and their heat protection properties - which were already inadequate – are reduced even more. Impressions of the boot 2013 The same thing can, incidentally, happen to suits that have been manufactured from a material that has not been made with the meticulous observance of formulation specifications and production procedures. Diving suits made from inferior material get thinner – and stay that way – after they have only been used for diving a few times. What conclusion do you draw, Neptune? It is at least generally the case that no risks are involved and no regrets have to be feared if brands are bought of the kind that well-known suppliers will be presenting soon at Boot 2013 (19. - 27. January 2013); a complete summary of all the suppliers exhibiting on the Messe Düsseldorf site can be obtained by entering the search word - diving (www.boot.de)

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