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Phenolic SMC for Automotive Fire Resistance
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on April 14, 2020 by SAE International in United States
Phenolic resins that meet REACH compliance and contain lower free-formaldehyde are safer to handle, compound, and mold. These resin systems do not contain any styrene or require any fillers to achieve their rated fire resistance. A commercial phenolic sheet-molding compound (SMC) is presented that achieves a 2-minute cycle time and addresses the unique requirements in an electrified vehicle architecture. This new SMC material includes all the industrially relevant considerations including material processing, shelf life, and surface finish. Other topics such as material hybridization and comparison to incumbent materials also discussed. The resin system uses a water-based phenolic resole which is acid-cured. This chemistry presents several unique challenges and opportunities for the industry such as managing formulation pH and appropriate methods for quality control. A demonstrator battery cover highlights the superior fire performance, impact resistance, and light weighting that is achieved with this resin technology. The phenolic SMC formulation is compatible with already established engineering fibers and textiles resulting in low-shrink, creep-resistant composites. The mechanical performance demonstrates strength and impact energy absorption greater than cast aluminum, with over 65% property retention after fire testing. Most importantly, the material economically meets the most restrictive automotive fire performance standards.