Sustainability is the driving force behind new developments in automotive

The speed with which the automotive industry is transitioning from internal combustion engines to battery power is breathtaking. We caught up with one of the industry’s leading suppliers of thermoplastics for an update and outlook on what is to come.

DuPont (Wilmington, Delaware) has been a supplier to the automotive industry for more than 100 years, so the company has had experience with managing change. But even its experts agree that the pace of change in today’s industry is unprecedented. “Our customers face tremendous challenges. Many need to balance their ability to continue developing their established range of ICE-powered vehicles, and at the same time rapidly develop applications for battery or hybrid electric vehicles,” notes Giacomo Parisi, marketing director for advanced mobility, referring to cars with internal combustion engines. “We believe we are in a great position to support as we know the industry so well, and that earned trust leads to open dialogue with customers about their challenges.”

Automotive OEMs incorporate a holistic mix of tactics to achieve their sustainability goals. One way is selecting materials with an environmentally-friendly footprint, such as bio-sourced materials or ones with high flow characteristics that help shorten cycle times and thus reduce energy costs.

A second path is to focus on the environmental footprint of the end application and improve this with the benefit of plastics’ properties such as weight reduction and the ability to design for parts’ consolidation.

But perhaps no change will have as great a sustainable impact as the transition to more battery-powered vehicles. A typical passenger car emits about 4.6 tonnes of CO² annually, according to the US Environmental Protection Agency. Most electric vehicles emit no exhaust.

Steam-Powered Factory and Bio-Feedstock

DuPont says it is working on solutions to support customers regardless of which path they take to improved sustainability. One example from the company of a recently developed sustainable solution for automotive and other applications is Delrin Renewable Attributed, the most recent addition to the company’s established range of Delrin polyacetal grades. Andreas Zöller, global product manager for Delrin, explains that the base polymer is manufactured using 100% bio-feedstock from waste, and is accredited through the International Sustainability and Carbon Certification (ISCC Plus) mass balance certification system. The bio-feedstock is supplied from second-generation sources not in competition with the food and feed chain. Taking it a step further, the facility where the base polymer is produced, in Dordrecht, the Netherlands, is powered with steam derived from energy recovery.

The new material clearly has a pedigree that supports automotive parts manufacturers' goals for improved sustainability. In addition, notes Zöller, it is a drop-in transition for manufacturers already specifying the company’s other polyacetal grades.

Automotive parts suppliers are keen to process more sustainable solutions, explains Laurent Lefebvre, automotive marketing director, but these solutions usually need to fit, easily, into established processes. “The industry is developing at such a rapid pace, and our customers are continuing to optimize their older lines while also investing in capacity for new BEV-related applications,” he notes. As a result, manufacturers prefer drop-in solutions that do not require extensive testing or new investment. For Delrin Renewable Attributed, typical applications in automotive include gears, seatbelt systems, moving parts within doors, and fasteners and clips.

Charging Forward with Battery Design

According to Giacomo Parisi, marketing director for advanced mobility solutions, the company’s development work is steered by what he calls its “battery roadmap.” The company has taken feedback from its customers and OEMs to develop this roadmap to track both near-term needs of the industry as well as the challenges related to technologies expected to emerge in the next 5-10 years.

To boost the range and reduce the charging times of battery-powered vehicles, energy density in battery cells will have to increase, with DuPont predicting this increase could reach as much as 2-3x current levels in the next 10 years. Increased density will help speed charging of full battery as well as hybrid powered vehicles (collectively called xEVs), increase safety, and improve performance in extreme cold or hot weather.

This change in battery density will require Tier suppliers to find materials that can meet the increased demands for crashworthiness, electrical insulation, thermal insulation and thermal runaway, among other potential challenges.

OEMs are eyeing a handful of options to keep high voltage batteries cool for xEVs. These options all have one thing in common – the need for thermoplastics and thermoplastic elastomers with a careful balance of thermal and dimensional properties. To keep xEV batteries cool, four main methods are considered: passive cooling, air-forced cooling, indirect cooling with water/glycol or refrigerant, or direct immersion cooling.

Especially for the latter two options, DuPont feels very well positioned to support customers. These two options require applications such as cooling plates, electric driven pumps, and other applications for which materials across the DuPont portfolio have been optimized.

Of these options, DuPont’s experts believe direct immersion cooling may offer the most upside, but they recognize that it also creates new challenges. Those challenges include the need to re-design the cooling system and ensure it does not leak any of the di-electric fluids. Direct immersion cooling also will place higher demands on the materials, including thermoplastics, in contact with those new EV fluids.

But the advantages – including faster charging, more precise temperature control, and improved cell lifetime – are very attractive to OEMs. What’s more, improving vehicle range is especially important to overcome consumer concerns range anxiety and especially the time required for charging. Increased consumer acceptance of xEVs would have a greater improvement on sustainability than, say, replacing a 50g metal part with a lighter one molded from thermoplastic.

Near term, increased battery density is being achieved via Cell-To-Pack (CTP) design, which requires advanced adhesive joining technology to enhance pack durability. Another example to improve motor efficiency, and ultimately reduce energy consumption, is a development led by DuPont to improve the design of hybrid bobbins, an integral part of e-motors.

Typically, these bobbins are made using PPS or PPA of a thickness of 600 to 800 microns. This thickness reduces the space for winding of the bobbin and hinders heat transfer to the metal core. DuPont engineers developed a hybrid bobbin design that benefits from the high insulation properties and chemical resistance of a grade of Zytel HTN specialty polyamide as well as the company’s Nomex(R) heat- and flame resistant fibers. Motors designed with this technology can generate more power in less space thanks to lower volume of the bobbin in the corner areas. Manufacturing efficiency is also improved; removing plastic insulation enables automated production of these bobbins. DuPont’s solution has already been adopted by one global OEM.

In addition to technology such as Nomex, DuPont believes it has another ace in the hole to support customers in the automotive industry. The company is not only a global leader in thermoplastics for the industry but also a leading supplier of the adhesives used during vehicle assembly. In many cases, these adhesives enable, for example, thermoplastic-to-metal or thermoplastic-to-rubber bonding.

The company’s adhesives business has recently launched several solutions that improve EV safety and performance, including thermally conductive adhesives that enable faster charging. “We see many opportunities for our company to support advanced mobility applications both separately- offering adhesives or thermoplastics- but also on applications where we can bring multi-material expertise to a customer,” notes Parisi.

Metal Replacement Developments Continues at Swift Pace

For decades, thermoplastics have chipped away at metal’s use in underhood parts in ICE-powered vehicles, and this trend continues apace in these as well as in xEVs. No matter the propulsion type, “We see significant interest among customers in solutions that offer improved heat resistance,” explains Lefebvre,

In many cases the reason for the interest is the same as it has been for many years; the shift from metal to thermoplastics enables the combination of multiple parts, new parts design, and more efficient manufacturing. The difference is that Tier suppliers in the automotive industry now are developing and moulding new applications for xEVs. These include new types of connectors, parts for electric motors, and battery housings.

Flame retardance on new vehicle applications greatly favours more sustainable non-halogenated solutions. Within e-motors, some of the parts have sustained temperatures of 130°to 170°C, requiring the development of new grades that are up to the challenge. Small sensors and connectors also require flame retardance, and often on very thin (0.4mm or even thinner) parts responsible for data transmission.

Lefebvre says new applications also often require EF (electrically friendly) materials such as the recently developed Zytel HTN EF grades. By preventing electrolytic corrosion, these materials help to extend component lifetime. Zytel HTN EF also retains its electrical and mechanical properties even after aging in ATF fluids and the new dielectric fluids used for component cooling.

“We are already supporting customers as they look ahead to next-gen sustainable goals,” explains Lefebrvre. “it is a very exciting time to be part of this industry- exciting and challenging. Between the solutions we already have launched for our customers, and the many in our developmental pipeline, we feel well positioned to continue providing support as they manage the dynamics of the industry.”

This article first appeared in the August/September issue of Sustainable Plastics.