Bold, bolder, boldest – always daring
Some impressive figures
In 1974, plastics in cars represented approximately 3% of their total weight. Nearly forty years later, this ratio is almost ten times higher, as it now exceeds 25%. Over this same period, fuel consumption for cars has decreased by some 14%. The improved performance of modern engines is, obviously, not unrelated to this drop in fuel consumption, but it is not the only reason – far from it!
Lightness is the goal !
In Europe, the automobile market is currently at one of the most significant turning points in its history. As well as the level of competition, there are anti-pollution standards that are constantly more demanding to which the sector has to adapt. With the introduction of the Euro 6 standard from 2014, nitrogen oxide emissions from cars and other vehicles will be restricted to a maximum of 80 mg/km – i.e. an additional reduction of more than 50% in comparison with the Euro 5 standard of 2011 – which will have a major impact on diesel vehicles. Manufacturers are looking for ways to meet this challenge. One of these revolves around the weight of vehicles and the use of materials that are lighter than metal and comply with safety standards. The answer is obvious: plastics!
Lighter, but so much more !
Okay, so plastics enable us to put cars on a diet. But they are capable of so much more than that, and manufacturers have been aware of this for quite some time. These materials do not rust and there is very little deterioration even in the harshest of weather conditions; they provide better sound insulation; they stand up well to minor impacts, thus avoiding the need for repeated visits to the garage to repair the bodywork; their use requires moderate levels of investment. Finally and above all, they can take any shape, allowing designers to employ their talents to the full.
A discrete revolution
Plastics are crucial, or even paramount in modern vehicles, to such an extent that every time a new model is placed on the market, automobile journalists assess the suitability of the plastic selected. This is a new challenge for manufacturers to overcome: using the most aesthetically pleasing plastics to win over the most demanding motorists. Perceived quality is now part of the technical data in the same way as horsepower! Have a look round your car and take a note of the materials. Plastics are everywhere! In a standard vehicle they comprise 25 % of the exterior, 50 % of the interior, and they account for 20 % of the materials under the bonnet and 10 % underneath the chassis.
Some debuts in the front line
For a long time, the dashboard has been the most visible plastic element in a vehicle’s interior. Then plastics quietly inserted themselves into the door trimmings and seat covers. Today’s dashboards are made from a polymer concentrate. Polypropylene (PP), acrylonitrile butadiene styrene (ABS), polyvinyl chloride (PVC)… they are foamed and brushed and turned into the most “convoluted” shapes in order to meet the aesthetic demands of drivers. Perfectly mastered casting techniques allow the different elements to fit together to the nearest millimetre. As well as providing important information to the driver, the modern dashboard must be attractive while at the same time resisting the damaging effects of UV and heat. In the vast majority of cases, it is composed of a reinforced ABS with polymer foam, which is as easy on the eye as it is smooth to the touch.
Plastic seats! People over 30 will not be surprised, as they will remember the imitation leather car seats from the 1970s. Intended to compete with real leather, they had one major problem: they burned your legs when they became hot. Although synthetic fibres gradually became more prevalent in seat covers, the frames themselves were still made from metal. Not for much longer! Manufacturers are more and more interested in plastics and in the near future will come up with new types of seats. The metal frame of the backs will be replaced by a monobloc part made from a plastic material that, with renewed effort, will enable the amount of foam and covering to be reduced. The main structure will be made from a composite material composed of layers of continuous fibre reinforced thermoplastic (CFRT) materials, moulded a second time with a polyamide. The back will weigh about 20 % less than a current car seat and will be about 30 mm thinner, a significant advantage in making the car lighter and more spacious.
LEDs in the limelight
Although polycarbonate headlights have already been around for a few years, they are now supplemented with a LED strip that is quite common on new models. Is this just a fad? Not really, although it is true that manufacturers initially considered them to be an optional extra for top of the range vehicles. Designers effectively used them as a signature feature, a way of immediately identifying a model at any time of day or night. But these LED strips are not only there to look pretty. They are very energy efficient and extremely durable, and they switch on with the very first turn of the key, making them a significant safety factor that makes vehicles more visible.
The other external elements also benefit from the higher technical capacities of plastic materials. A bonnet, a tailgate, a bumper face bar: for decades these parts have been made from plastic, like the wheel arch linings and the protective guards located underneath the vehicle. Car and parts manufacturers fully intend to make further progress in bringing this material into general use in doors and even windows. The savings in weight achieved will be colossal without affecting the safety of the vehicle, something that is now a key factor in the decision to buy, in the same way as design, fuel consumption or reliability.
To find out more, please read the interview with Gérard Liraut, head of the Polymers and Fluids Department at Renault www.plastics-themag.com/plastic-viewpoints/plastics-go-ahead-for-innovation-at-renault
Tyres go green
Is the so-called green tyre a marketing coup, another example of “greenwashing” – a deceptive marketing technique that allows any means to be used when it comes to creating a positive environmental image? Let the sceptics rest easy, for it is quite the opposite. Tests show that these green tyres result in a significant decrease in fuel consumption, improve braking efficiency and have a longer lifetime. This may not be generally known, but the role played by tyres in the fuel consumption of a vehicle is far from insignificant. As the car moves, the tyre loses its shape and heats up, causing resistance to the movement, which in turn uses up energy. The secret solution is high performance synthetic rubber integrated with the composition of the tread. The tyre does not heat up so much on contact with the road surface, loses its shape to a lesser degree and thus allows a substantial improvement in fuel consumption.
At the present time, the European Union is proposing to make “energy labelling” for tyres compulsory by the end of the year, and there can be no doubt that this innovation will soon prove to be a real success.
Homepage picture : © Goodyear