COMPOUNDS | AUTOMOTIVE
Right: Addressing the needs of compounders working with PBT in EV platforms: Sebastian Hoerold, Senior Expert Flame Retardants at Clariant
significantly higher temperatures in battery modules, busbars, connectors, and power electron- ics, while traditional halogenated flame-retardant systems are giving way to halogen-free alternatives that satisfy environmental regulations without compromising performance. Compounders are also investing heavily in phosphorus-based, mineral-filled and synergistic additive technologies capable of dissipating heat while maintaining dielectric performance. Beyond flame retardancy, the emphasis has shifted towards multifunctional compounds combining high dielectric strength, thermal conductivity, low smoke generation, chemi- cal resistance, long-term hydrolytic stability, and mechanical durability. This integrated approach allows a single material to address multiple engineering requirements while simplifying component design.
Thermal Shock “Thermal shock is an important issue because mod- ern EVs operate across a wider temperature range,” said Arthur Rieb, Business Development Manager e-Powertrain, Envalior. “Components may experi- ence rapid transitions from very low ambient temperatures to high operating temperatures generated by fast charging, regenerative braking, or high-power driving conditions. The combination of repeated thermal cycling and increasingly compact designs places greater demands on materials.” Xytron M5080ET was developed by Envalior to
address these challenges. Rieb said key features include its thermal expansion behaviour, which is significantly closer to that of copper compared with conventional solutions, and its ductility, which means the material has a higher elongation at break. “By reducing the mismatch between the copper conductor and the overmoulded polymer, internal stresses are minimised, helping reduce stress cracking during thermal shock events,” he said. “Testing has demonstrated more than 70% higher thermal shock stress crack resistance compared with comparable PPS compounds.” At The Battery Show North America, in Detroit last October, Envalior debuted Pocan BFN4232ZHR S1, a hydrolysis-stabilised, flame-retardant PBT which helps prevent silver migration and electrical stress, two major causes of breakdowns and arcing in high-voltage environments. The company also showcased the first fully functional high-voltage battery enclosure made entirely of engineered plastics, developed from Durethan B24CMH2.0 + 45% LGF PA6 and Tepex Dynalite 102-RGUD600 thermoplastic composite sheet technology which
50 COMPOUNDING WORLD | September 2026
achieves lower weight, cost, and carbon footprint, compared to traditional metal housings.
Flame retardancy In the field of additives, Clariant has expanded its Exolit OP portfolio with two new PBT flame retard- ants (FR), each targeting a specific engineering challenge. The first, Exolit OP 1242 (TP), addresses hydrolysis stability, an important property in automotive environments where components are exposed to moisture, humidity, and temperature fluctuations over long service lifetimes. Not all FR systems maintain their performance under these conditions and certain synergist combinations commonly used with phosphinate-based flame retardants can reduce hydrolytic stability. The other new Clariant FR product, Exolit OP 1266 (TP), targets tracking resistance, providing a stable comparative tracking index (CTI) of 600 V in PBT compounds, even after extended storage periods. Both products achieve UL 94 V-0 classifica- tion at sample thicknesses as low as 0.4 mm, at dosing levels of 15–20% which supports EV manufacturers looking to reduce component weight and size.
Beyond their technical performance, both new
offerings are halogen-free alternatives to traditional brominated FR products combined with antimony trioxide (ATO), which has seen significant price increases and supply chain volatility in recent years. OEM requirements around material composition are also tightening, and a halogen-free, ATO-free, PTFE-free approach helps manufacturers address this trend. Further development is targeting long-chain PA materials like PA 12 where the
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IMAGE: CLARIANT
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