Challenges for plastics in the cars of the future

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The replacement of heavy materials such as metals or glass with plastics has acquired new impetus as a result of advances in electromobility. The increase in the use of powerful batteries and electric motors means that plastics incorporating electrically conductive screening or permanent antistatic features are acquiring additional importance. Grafe engineers, Dipl-Ing. Steffen Felzer, Danny Ludwig and Manuel Heimerl, have been giving some thought to current trends in mobility and set out the activities of the group in this area.

Battery cover (photos: Grafe)

Electromobility in automotive construction – the beginnings

Electromobility is not a discovery that can be claimed by our century, but is one that can look back on a distinguished history. Around 130 years ago Gustave Trouvé presented his three-wheeled, electrically driven automobile. This, the world’s very first electric car, was able to reach a speed of 12km/h and was driven by two motors. It was powered by lead batteries with a range of between 14 and 26km. Then, in 1899, an e-car smashed the speed record of 100km/h. With the meteoric development of ever faster and more powerful motor vehicles at the beginning of the 20th century, electric cars faded from view, in no small measure due to the heavy batteries, lengthy charging time and short range.

Application areas for thermoplastic polymers

With increased concern for the environment, changes in society, and, not least, the possibility of constructing more powerful and smaller batteries, electromobility once again started to reawaken increased interest at the end of the last century. More environmentally friendly, more sustainable, these became the watchwords for electric motor vehicles, but they also needed to prove they could go the distance. It was then that plastic started to play an increasingly important role in electromobility. The decisive factors in the use of plastics are not only their flexibility and formability, but also – most importantly – their strength and stability. An electrically-powered drive offers the opportunity to minimise emissions and to reduce dependence on finite resources such as oil and gas. 100kg less weight corresponds to around 0.3l/100km less consumption and, depending on the fuel, approximately 10g less in terms of CO2 emissions.

For masterbatch and compound manufacturers, the challenges presented by new concepts such as electromobility and hybrid motor vehicle are clear: the emphasis on economy, the environment and sustainability.

Airflow from a low emission PP compound

Airflow from a low emission PP compound

Options as far as plastics are concerned

CFRP materials: Among the high quality fibre composite materials are carbon fibre reinforced materials. With the help of these composites it is possible, despite a reduction in weight, to achieve high rigidity and strength in car components. Fibre composite materials are making significant inroads in lightweight constructions. CFRP construction has even become a feature of modern bodywork. In addition, the engineers at Grafe are also carrying out research and development work on C plastic composites, where recycling is also playing an increasingly significant role.

Lightweight construction: Lightweight construction in multi-material design is coming to be recognised as the key future-orientated technology in electromobility. The use of plastics will save weight, increase durability, and the aesthetics of the vehicle will be influenced by this increased use of plastics. Heavy materials such as metals and glass are being increasingly replaced by plastics. This not only applies to interior components such as covers and column claddings but also electrical screening and dissipative plastic structures. Electromagnetic screening is carried out as a rule on housing parts using cable sheathing or line cladding. This includes screening covers for distributor caps and ignition cables. But self-regulating heating elements for motor vehicle mirrors or screen washer jets are also manufactured from electricity conducting plastics. These are growing in importance with the increased use of powerful batteries and electric motors. The safety factor in the automobile is coming under scrutiny due to the increase in the number of battery components and electric motors. The batteries in an electric car are exposed to extreme loads since, during the lengthy charging progress, many hundreds of amps worth of current will be flowing. The battery consequently becomes very hot and the material stressed. This is a challenge for masterbatch and compound manufacturers to come up with low weight, process-reliable, cost efficient but also robust components, a far from straightforward task.

Electrically conductive plastics. There are other significant considerations to take into account. Plastics are good insulators, but unable to resist electromagnetic radiation. There is a risk of electrostatic discharge and spark formation, with the consequent threat to electronically sensitive components, not to mention the health and safety implications. One alternative solution is to use plastics that are electrically conductive or which incorporate a screening facility or a permanent antistatic feature. Grafe Polymer Technology has developed and carried out project work on plastics that are electrically conductive and which incorporate permanent antistatic and screening features.

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