A new fluoroelastomer grade helps automotive parts manufacturers meet unique regulatory and design requirements of elastomeric fuel system barrier hose applications such as small diameter fuel and vapor lines and larger diameter fuel-fill hoses. The material, called Dyneon THV X815G has been developed by Dyneon a 3M company, and one of the World's leading fluoropolymer producers. Dyneon THV (a polymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride) provides a combination of performance advantages, such as low processing temperature, ability to bond to elastomers and hydrocarbon-based plastics, flexibility and optical clarity. These products are also used in a variety of markets and applications such as the chemical processing industry, semiconductor manufacturing, solar energy, polymer optical fiber and architectural/protective coatings.
With the adoption of new hydrocarbon emission regulations in the US, Dyneon THV 500 became a preferred permeation barrier for elastomeric hoses. Dyneon THV X815G enables much lower permeation constants compared to the earlier series, helping a variety of hose constructions to meet more stringent requirements. It provides the low permeation performance that is critical in applications where the THV layer serves as the first line of defense against evaporative emissions, helping the entire fuel system to meet industry regulations like CARB LEV II and EPA Tier 2. The performance characteristics enable fuel fill hoses to be made in longer lengths without sacrificing durability or permeation resistance. It is bondable to it and other substrates (for multi-layer constructions) and can be co-processed with many hydrocarbon elastomers. Additionally, in accordance with OEM material specifications, Dyneon fluoropolymers used in automotive applications do not contain extractables that can clog fuel systems.

Viton® by DuPont Dow Elastomers exhibits resistance to a broader range of chemicals combined with very good high temperature properties more than any of the other elastomers. Viton provides faster curing, shorter cycle times and significantly enhanced demolding and end-use performance. Increasingly stringent regulations are pushing automotive evaporative emission limits beyond the capabilities of many sealing materials. Consequently, fuel system and engine sealing OEMs are said to have been searching for next generation materials with fuel permeation performance to meet US LEV II and PZEV (Partial Zero-Emission Vehicle) regulations and Euro 4 requirements. The material offers superior permeation resistance to meet or exceed all of the current evaporative emission requirements for air induction systems. Viton has met the requirements needed for a gasket seal material that would comply for at least 15 years/150,000 miles of vehicle life to meet LEV II and PZEV requirements. Th material runs at the same production rate and cavitation as a silicone tool, offers a good blend of processability, cures very tight and consistent, and the company is said to have developed an optimal formulation that works very well with robotics.