For decades, Sarlink® TPVs have been steadily displacing EPDM rubber in automotive weather seals. The main drivers for switching from EPDM to TPV are performance enhancements, including weight reduction, and improved manufacturability. There are recycling benefits from switching to TPV as well. All of these factors make Sarlink TPVs the more sustainable material choice.
We’ve had years of experience helping automotive sealing manufacturers convert EPDM profiles to Sarlink TPVs, and we’ve condensed this knowledge into this quick reference guide to help you make more informed decisions about material selection.
Performance Enhancements
Sarlink® TPV and EPDM rubber make excellent sealing materials due to their elasticity, resilience, and toughness. How do they differ? Sarlink® TPVs are actually alloys of EPDM and polypropylene, and therefore combine the performance benefits of both thermoset rubber and thermoplastics. The table below highlights these features and benefits:
|
Sarlink® TPV Features |
Benefits |
|
|
Elastic Performance |
• Short term compression set
(22 hr at 70oC): EPDM has lower values than TPV
• Long Term compression set
(1000 hr at 70oC): TPV has lower values than EPDM • Load loss values follow a similar trend
|
• TPVs maintain sealing performance over time
|
|
Colorability |
• TPVs are colorable
|
• Color matching available for JA6 and R600,
glass run channels or secondary seals |
|
Heat Aging |
• TPVs retain physical properties better than
EPDM at elevated temperatures |
• Maintains sealing performance in hot
environments |
|
Weather Resistance |
• TPVs retain color much better than EPDM
• TPVs retain physical properties better than
EPDM • TPVs do not chalk or crack
|
• Maintaining color harmony and original finish
• Less susceptible to cracking or tearing
|
|
Chemical Resistance |
• TPVs have better chemical resistance due to
PP encapsulation of EPDM particles |
• Less swell and/or degradation of seals where
in contact with cleaners or waxes, less chemical interaction |
Weight Reduction
There are three ways Sarlink TPVs contribute to light-weighting of vehicles, contributing to fuel efficiency:
- Lower density (specific gravity) than EPDM: With a specific gravity of 0.95 vs. 1.25, TPV seals are 30% lighter using the same design
- Optimized seal designs: TPV profiles can be designed with thinner walls, but achieving equivalent functionality
- Optimized materials usage: High durometer TPV grades can replace the metal carrier in glass run channels
Improved Manufacturability
The figure below compares the process of manufacturing a TPV seal versus that of EPDM. With less manufacturing steps and the use of conventional thermoplastic extrusion equipment, Sarlink TPVs require a smaller manufacturing footprint, consume less energy, and reduce capital investments.
Basic Part Production: Sarlink® TPV vs. EPDM Rubber
Recycling Benefits
Sarlink® TPVs can be recycled. EPDM rubber requires cross-linking (vulcanization) to achieve its properties; creating irreversible bonds that will not re-melt when heated. The EPDM used in Sarlink® TPV, however, is dynamically vulcanized during the compounding process, and the cross-linked EPDM rubber particles are encapsulated in a polypropylene matrix. Thus, like polypropylene, Sarlink® TPV can be heated and melted many times, making it an excellent candidate for recycling. TPV scrap recovered from any step in the manufacturing process and can be reintroduced into the process or used in the production of other parts. This is quite common and is a major advantage over EPDM manufacturing in terms of yield and sustainability. The figure below shows the recycling stability of Sarlink TPV: Even after recycling six times, critical physical and mechanic properties of Sarlink TPVs remain stable.
Recycling Stability of Sarlink® TPV
Conversion from EPDM to Sarlink® TPV
The Teknor Apex team is ready and able to guide you through the process of converting from EPDM to TPV. From material selection, to part and tooling design, to process optimization – we’ve got you covered. Our in-house application development capabilities for automotive sealing is unmatched in the industry. Feel free to contact us to talk through your latest project or download the case study below to learn how we helped a major Tier 1 supplier reduce weight and cost while improving performance of glass run channels.
