ExxonMobil Chemical's New Database for Santoprene TPVs Improves Part Design and Reduces 'Over-Engineering'

19 Dec 2007 • by Natalie Aster

HOUSTON -- ExxonMobil Chemical recently introduced a new design tool that can help engineers predict the long-term behavior of Santoprene™ thermoplastic vulcanizates (TPVs). The new "compression stress relaxation database" helps predict how Santoprene TPVs perform initially and then at any time during the expected life of the part. This enables engineers to create more effective designs, improving part reliability while reducing material use and costs.

Without this type of data, engineers have typically applied arbitrary safety factors to their designs to account for diminishing performance caused by stress relaxation over time. Because these safety factors are estimated, parts are often over-engineered to ensure they do not fail. This increases material use and costs.

The database provides design engineers with more confidence as it helps them to ensure that the part will meet the specified performance requirements of the application.

"This set of data is particularly important in applications like seals, as in time the material will relax and creep, causing a predictable decline in performance," said Ward Narhi, senior design engineer, ExxonMobil Chemical's Santoprene specialty products. "To achieve an effective design, it is important to have a good understanding of the material's long-term behavior."

When designing a seal, an engineer must know the level of sealing required at the beginning of its life, which can be calculated using finite element analysis (FEA) or determined through prototype testing. From there, this new database helps to accurately plot the long-term performance of the material at any point in the future.

This compression stress relaxation data is available at different temperatures (23 C, 70 C, 80 C, 100 C and, for some grades, minus 40 C) for the Santoprene TPV sealing grades used in pipe, automotive, construction and general purpose applications.

"The new database enables engineers to 'design smart,' helping them to eliminate over-engineering, improve part reliability and lower costs. This database can be particularly valuable in automotive applications where less material can result in lower weight, leading to reduced fuel consumption," said Narhi.

Designers can access the free database and detailed instructions on how to use it online. The database can also be used to compare different materials to determine which offers optimum long-term performance for specific applications.

ExxonMobil continues to add to its extensive collection of online technical information. Designers can also access other design engineering databases for Santoprene TPVs, such as one for cyclical behavior and another for FEA.

About ExxonMobil Chemical

ExxonMobil Chemical is a global leader in technology, product quality and customer service with petrochemical manufacturing and/or marketing operations around the world.

About ExxonMobil Chemical's specialty elastomers

ExxonMobil Chemical offers customers one of the industry's broadest portfolios of specialty elastomer products. This includes Vistalon™ EPDM (conventional and metallocene catalyst), Santoprene™ brand TPVs, Vistamaxx™ specialty elastomers, Exxelor™ modifiers, and Exact™ plastomers. These products provide innovative elastomeric solutions combined with global support in material selection, design, processing, and supply chain management.

Vistamaxx, Vistalon, Exxelor and Exact are trademarks of ExxonMobil Chemical. Santoprene is a trademark of an Exxon Mobil Corporation affiliate. The term "ExxonMobil Chemical" refers collectively to some or all of the companies affiliated with Exxon Mobil Corporation which have chemical manufacturing and/or marketing operations around the world.

Source: ExxonMobil Chemical