How do TPV sheets in automotive sealing systems balance high elastic recovery and long-term compression set performance?
Publish Time: 2026-01-15
In modern automotive design, sealing systems not only concern basic functions such as sound insulation, waterproofing, and dustproofing, but also directly impact the overall comfort, safety, and durability of the vehicle. As a significant upgrade and replacement for traditional rubber materials, TPV sheets, with their excellent comprehensive performance, are widely used in key components such as door seals, sunroof seals, trunk lids, engine hoods, and new energy battery packs. However, seals are prone to "compression set" under long-term pressure—that is, they cannot fully rebound after unloading, leading to seal failure and air/water leaks.1. "Sea-Island" Structure: The Physical Basis of Elasticity and StabilityTPV is a thermoplastic elastomer formed by highly cross-linking EPDM rubber microparticles and uniformly dispersing them in a continuous polypropylene phase using dynamic vulcanization technology. This microstructure, with "rubber as islands and plastic as the sea," endows the material with dual properties: the cross-linked EPDM microparticles provide high elasticity and heat resistance similar to thermosetting rubber, while the continuous PP phase provides ease of thermoplastic processing. Under pressure, EPDM particles undergo reversible deformation; upon decompression, their three-dimensional network structure rapidly drives material rebound. More importantly, the highly cross-linked rubber phase significantly restricts the slippage and rearrangement of molecular chains under long-term stress, fundamentally inhibiting compression set.2. Precise Formulation Control: Optimizing Crosslink Density and CompatibilityThe compression set performance of TPV is closely related to the crosslink density, particle size distribution, and PP/EPDM compatibility of the rubber phase. By adjusting the vulcanization system, compatibilizer type, and filler oil ratio, the degree of crosslinking and interfacial bonding strength of the rubber particles can be precisely controlled. For example, moderately increasing the crosslink density can enhance resilience, but excessively high density can lead to material brittleness; while introducing maleic anhydride-grafted PP as a compatibilizer can strengthen the interfacial adhesion between the two phases, preventing micropores or phase separation during compression. High-end automotive-grade TPV typically controls the compression set at 150℃ for 22 hours to ≤25%, far superior to ordinary TPE, and approaching or even exceeding the level of partially vulcanized EPDM.3. Thermal History and Processing Technology: Ensuring Microstructural IntegrityThe extrusion or calendering process of TPV sheets significantly impacts their final performance. Excessively high processing temperatures or shear rates can lead to PP degradation or excessive fragmentation of the rubber phase, disrupting the uniformity of the "sea-island" structure. Therefore, advanced production lines employ low-temperature, high-torque extrusion combined with precision roll forming to ensure melt flowability while maximizing the preservation of the complete cross-linked network of rubber microparticles. Furthermore, some manufacturers introduce online annealing to eliminate internal stress and further improve dimensional stability and resilience consistency.4. Real-World Testing: Reliability from Laboratory to RoadAutomotive seals need to operate for over 10 years at temperatures ranging from -40°C to 125°C or even higher. TPV sheets undergo accelerated aging tests and dynamic fatigue tests to verify their long-term sealing reliability in real-world environments. Data shows that high-quality TPV maintains a resilience rate of over 85% even under high temperature and humidity conditions, with slow growth in compression set, effectively preventing abnormal noises, water leakage, or increased energy consumption due to seal failure.5. Added Value of Lightweight and Sustainable AdvantagesIn addition to performance advantages, TPV has a density 10%–20% lower than traditional EPDM, contributing to overall vehicle lightweighting; it is also 100% recyclable, aligning with the automotive industry's green development trend.In summary, automotive component TPV sheets achieve an excellent balance between high elastic recovery and low compression set through intrinsic material structure design, precise formulation control, and rigorous process control. It is not only an upgrade in sealing technology but also a key material support for the automotive industry's progress towards high performance, long lifespan, lightweighting, and sustainable development.
