The transformation from the combustion to the electric engine entails several imponderabilities for the plastics industry. In part, electric drives have completely different material requirements which are becoming specifically evident with the increasing use of appropriate vehicles.

In electric vehicles, the change in engine technology also entails new requirements for the plastic materials used

Flame Retardancy, Heat and Tracking Resistance of Electric Vehicles

Elektromotoren

Antriebe

Kfz-Elektronik

Elektronik

Elektromobilität

Mobilität

Kunststoffe

Photonik

Optik

Polyamide

Kunststoff Werkstoffe

Thermoplaste

Elektronische Bauelemente

Leistungselektronik

Technische Kunststoffe

Hochleistungskunststoffe

Drivers of Electromobility

Ascend Performance Materials will focus on electromobility and sustainability at K. The company made this announcement at a press conference in advance of the trade show.

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Messe K-Kunststoffmesse

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Wide Range of PA Innovations

Special plastics are needed for the increasingly widespread 800 V drives of electric cars. Bio-based PPA, for example, represents a sustainable option.

Faster and More Sustainable Charging

The conditions in electric vehicles place high demands on the materials used. Therefore, automakers and suppliers must resort to expensive, high-performance plastics. For many applications, cost-effective alternatives are plastics whose properties have been greatly improved by means of treatment with high-energy electron beams.

Fig. 1. Crosslinked engineering plastics can be used for many different applications in electric vehicles.

Irradiation Crosslinking Replaces High-Performance Plastics with Cheaper Polymers

Strahlenvernetzung

Kunststoffverarbeitung: Verfahren

Kunststoff-Aufbereitung

Electron Booster for Electric Vehicles

Electrical architecture in an E-car is significantly more challenging than for conventionally powered vehicles. Particularly for insulation of high-voltage (HV) components, the demands on the materials used are increasing. With specially-tailored materials for electric vehicles, challenges in automotive high-voltage technology can be overcome.

Insulation of high-voltage components in electric vehicles makes high demands on the materials used

Polyamide Specialties for Electromobility

Automotive

Kunststoff

Bauwesen

Baustoffe

High Voltage in Cars

Electric-vehicle makers looking for fresh impetus are turning to thermoplastics, as these can be used to  improve the safety, performance and sustainability of the vehicles. Initial application areas for manufacturers can be found in a multitude of components ranging from battery cases to busbars, cooling lines and seals. Things become very interesting when material suppliers offer support in the form of CAE and injection molding analyses.

Thermoplastics play an important role in the batteries of electric vehicles. They help to keep battery temperatures in the optimal range for a long service life and high performance. 

Improving the Performance of Electric Vehicles with the Right Materials

Electric, Environmentally Friendly, Thermoplastic

Electromobility in particular, but also many other electrical applications, are asking for ever higher demands regarding the electrical properties of thermoplastics. This raises the question of whether the polymers commonly used in this area can still meet these demands. The plastics manufacturer, Lanxess, has now investigated how suitable, for example, polyamide and polybutylene terephthalate are for use at higher voltages and temperatures.

How Suitable Are PA and PBT for High-Voltage Applications?

Polybutylenterephthalat

Against the Current

A focal point of the Lanxess booth at the show this year will be materials for electromobility.

The demonstrator of a near-series- production housing for electric vehicle batteries is one of the highlights at  the Lanxess booth.

Demonstrator for EV Battery Housings

Electric vehicles can be charged not only at charging stations, but also wirelessly. Here, the energy exchange takes place between an induction coil positioned in the ground and a receiver coil mounted in the e-car.

Wireless charging could increase the range, and therefore the acceptance of electromobility.

Flame Retardant Polyamide for Inductive Charging Systems

No Cable thanks to Suitable Compounds

Due to the climate change, new fields of development and sustainability topics have come into focus along the added-value chain.

Polyamide continues to be one of the most important technical plastics in the automotive sector, where it enjoys widespread use. This not only applies for classical internal combustion vehicles, but in terms of volume will also be the case for electric vehicles.

Polyamides: Electromobility and Sustainability Boost Developments

Kunststoff-Recycling

Dual Change with Polyamides

The rising voltages in electric vehicles are creating higher requirements on insulation materials. This is why PEEK is increasingly used for this purpose. A problem with this high-performance polymer used to be its adhesion to the secondary insulation material. An epoxy resin now promises to solve the issue.

Due to higher voltages, manufacturers are increasingly using PEEK as insulation material for electric motors.

Partner for PEEK

Polyetherketon

PEEK and Epoxy Provide Efficient Insulation for High Voltage E-Motor

The global market for PBT has recovered well from the aftermath of the corona pandemic. However, there is a lot going on among manufacturers at the moment.

PBT compounds are very much in demand for electromobility, including for parts of the battery, electric transmission and the charging infrastructure.

Polybutylene Terephthalate (PBT): Demand for Products with Added Benefits

Electromobility and Sustainability Are Driving Growth

At K 2022, it was clearly shown that with suitable materials not only can CO2 emissions be reduced, but also advantages in component design achieved.

The Japanese chemical company Asahi Kasei showed its concept vehicle at K 2022. The domed roof in particular could lead to a few changes in future automobiles.

With suitable materials CO2 emissions can be reduced and advantages in component design can be achieved.

Automotive Highlights of K 2022

Thermoplastische Elastomere

Silikone

Kunststoffe, biobasiert

Biokunststoffe

Streifinger, Florian

Polymethylmethacrylat

Polycarbonat

Suitable Materials for Smart  Vehicle Design

Long fiber thermoplastic compression molding is suitable for the production of components with large surfaces such as battery enclosures for electric vehicles. However, these components place high demands on the material used.

Large-area components, like the battery cover shown, can be produced very well using direct long fiber compression molding. Optimized materials such as PA66 Mobius NPD 555 FR GF50 from Invista  are ideal for the process involved.

Two resin grades developed for long fiber thermoplastic compression molding permit the substitution of thermosetting SMC molding materials.

PA66 for Flame Retardant Large-Area D-LFT Components

Pressen von Kunststoffen

Faster Process to Safe Battery Enclosures

One of Ascend’s product ranges has demonstrated how the carbon footprint of PA can be reduced. The company has taken an additional stake in a recycler.

Instead of disposing of worn-out carpets in landfills or incinerators, recycling is a better alternative.

Recycling

Umweltmanagement

Kunststoff-Rezyklat

Old Carpets Become New Polymers

A Comparison of PA66 and PPA for Electric Vehicles

With the change from internal combustion engines to hybrid and electric vehicles, peak operating temperatures have dropped from 135 °C to 110 °C. At the same time, the number of operating hours compared to combustion engines has increased nine-fold. This has an influence on material selection.

With the change from internal combustion engines to hybrid and electric vehicles, peak operating temperatures have dropped from 135 °C to 110 °C. At the same time, the number of operating hours compared to combustion engines has increased nine-fold. This has an influence on material selection. Whether high-performance polymers can be replaced by cheaper alternatives in future was evaluated by EMS using a PA66 and a polyphthalamide as examples.

The goal of nearly every research project is to find, among all possible solutions, the one solution with the greatest technical and economic significance. Technical significance is determined by the degree of fulfilment of the fixed, minimum and, in some cases, additional preferred requirements. These can be, for example, economic savings, higher effectiveness or longer working life. Manufacturing costs, i.e. material and processing costs, are taken as the main factor for economic significance.

Possible key technical factors are, for example, limited installation space, demand for a reduction in installation space, due to miniaturization for instance, or limited wall thicknesses as, for example, in sensor technology. In addition, increasing requirements, e.g. longer working life, reliability under unknown conditions and minimization of risks, are limiting any technical alternatives. Automotive manufacturers and suppliers are also facing major challenges due to the changeover from internal combustion engines to electric motors as the material properties required for the two technologies differ greatly in some cases (see Table). Among other things, the question arises of whether previously used high-performance materials can be replaced with less expensive alternatives. The polymer manufacturer EMS-Grivory has evaluated this, taking a hydrolysis-stabilized polyamide 66 (PA66) and a high hydrolysisresistant polyphthalamide (PPA) as examples. Currently typical representative materials were chosen; for PA66 a grade with 30 % glass-fiber content (PA66-GF30) and for PPA, a grade with 40 % glass-fiber content (PPA-GF40).

The most important physical differentiating features of the PPA used (product name: Grivory HT1VA-4 HY; manufacturer: EMS-Grivory) compared to the PA66 are a 55 °C higher glass transition temperature as well as significantly lower and slower water absorption (Fig. 1). In many cases, the lower moisture absorption and correspondingly better dimensional stability, is already sufficient reason to prefer the PPA over the PA66. In addition, HT1VA-4 HY exhibits clearly higher stiffness, strength and resistance to creep over a wide temperature range which, in contrast to PA66, is largely independent of the moisture content. Furthermore, PPA exhibits superior resistance to chemicals and hydrolysis.

For processing of the PPA, higher processing temperatures in the injection-molding unit and mold (oil tempering) are required compared to PA66. Shrinkage behavior of the materials differs, which can have an influence on dimensional tolerances. A direct transfer from PA66 to PPA in an existing mold is therefore generally not possible without modifications being necessary. For suitability tests of PA66 compared to PPA in cooling systems of electric vehicles, DIN tensile bars with a wall thickness of 4 mm were stored in a water-glycol mixture based on ethylene glycol with a mixing ratio of 1:1 at 110 °C in an autoclave for a period of 8000 hours.

After conditioning under the above mentioned conditions, the tensile stress at break value for PA66-GF30 dropped by more than 40 % to 127 MPa (Fig. 2). After 8000 hours, the value was 55 MPa, which corresponds to a reduction of 73 % of the original value in a dry state. For the PPA-GF40, the tensile stress at break value after conditioning was 240 MPa (-4 %) and after 8000 hours, 186 MPa (-25 %). After storage for 8000 hours in a water-glycol mixture at 110 °C, the PPA-GF40 shows more than three times higher tensile stress at break values than the PA66-GF30 examined. This corresponds to a performance increase of 240 % when using PPA.

In the case of PA66-GF30, micrographs of the tensile bars showed micro-cracks on the surface after conditioning for 8000 hours (Fig. 3). This is a clear indication of damage to the material after less than half the required minimum operating period of 20,000 hours. Designs with higher wall thicknesses can reduce the risk of failure due to the influence of temperature or media, although this makes the components heavier and requires longer cooling times in the injection-molding process, which has a negative effect on part costs. Micrographs of Grivory HT1VA-4 HY, on the other hand, show a perfect surface finish. Consequently, parts with lower wall thicknesses and therefore, lower weight, can be realized using this material. Thanks to its high strength and stiffness at high temperatures, PPA is particularly well suited for light-weight construction. Using this material, component wall thicknesses can be reduced to a minimum and savings achieved not only for part weight, but also for cycle times and, thereby, manufacturing costs.

As an example, a U-profile made of PA66-GF30 and one made of PPA-GF40, both with diagonal ribbing, were compared under bending stress. After storage in a water-glycol mixture at 110 °C, PPA has 3.4 times higher tensile stress at break values (Fig. 2) providing a performance increase of 240 %. The higher strength of PPA-GF40 compared to PA66-GF30 in this example allows wall thicknesses to be reduced from 5 mm to 2.5 mm with a simultaneous reduction in assembly height of 36 %, resulting in a volume reduction of 62 % (Fig. 4).

This reduction in wall thickness is however, limited by the flowability of the material. In this way, the theoretically calculated cycle time is shortened by 66 % resulting in overall manufacturing cost savings of 44 %. Calculation of these cost savings was made taking an average machine rate of 150 EUR per hour. Due to the lower density of PA66-GF30 compared to Grivory HT1VA-4 HY, use of PPA compared to PA66 results in weight savings of 58 % and cost savings of 38 %. The overall cost saving from lower volume and shorter cycle time amounts to 44 % (Fig. 5).

The performance increase using PPA compared to materials with lower strength, such as PA66, is dependent on the type of loading involved and the part geometry. PPA polymers provide design engineers with the possibility of designing components with optimal technical and economic significance. Using PPA materials such as the high hydrolysis-resistant Grivory HT1VA-4 HY, technical and economic improvements can be achieved for components requiring a combination of high strength with extreme resistance to hydrolysis.

The EMS product portfolio includes products for applications in automotive construction as well as for components in contact with food or drinking water and with between 30 % and 60 % glass-fiber reinforcement. The assortment is rounded off by grades for designs involving difficult demolding such as those with complex geometries or undercutting, as well as laser transparency with optical black pigmentation.

High-performance polymers such as PPA will continue to be in demand not only for applications in hybrid and electrical vehicles, but everywhere where maximum performance with a simultaneous reduction in part weight is required. Using products from the Grivory HT1VA series, robust, lightweight, long-lasting and reliable components are possible.

EMS-CHEMIE AG  

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Fig. 1. Compared to the PPA Grivory HT1VA-4 HY, even hydrolysis-stabilized PA66 absorbs significantly more water and more quickly (results measured on plates 100 x 100 x 3 mm according to ISO 62 at 23 °C.

Fig. 2. After storage for 8000 hours at 110 °C in a 1:1 water-glycol mixture, the tensile stress at break value for hydrolysis-stabilized PA66-GF30 dropped from 202 to 55 MPa (-73 %). PPA (Grivory HT1VA-4 HY) showed a drop from 249 to only 186 MPa (-25 %).

Fig. 3. Micrographs after 8000 hours storage in a water-glycol mixture (based on ethylene glycol, mixing ratio 1:1) at 110 °C. Grivory HT1VA-4 HY (at left) shows no damage. The PA66-GF30 (at right) however, shows various surface microcracks (marked in red). These indicate significant damage to the material.

Fig. 4. Selection of a PPA instead of PA66 makes a significant reduction in component volume possible. The flowability of the material sets definite limits for a reduction in wall-thickness however. 

Fig. 5. PPA-GF40 offers a large number of advantages compared to PA66-GF30.

Table. Requirements on the operating temperatures and duration of operating time for different types of vehicle.

KU 8-22_EMS - Hauptartikel

Albert Flepp is global product manager Grivory HT at EMS-Grivory.

EMS Grivory <a href="http://www.emsgrivory.com" target="_blank">www.emsgrivory.com</a>

Read the German version of the article in our magazine Kunststoffe or at <a href="https://www.kunststoffe.de/a/fachartikel/mehr-leistung-im-wasser-2856293" target="_blank">www.kunststoffe.de</a>