Advancure™ Hexamethylenediamine Curative in Guanidine-Free Cure Systems for Vamac®

DuPont Vamac® ethylene acrylic elastomers (AEM) are designed to withstand high and low temperatures and aggressive new automotive fluids in under the hood automotive applications such as seals, gaskets, ducts, hoses and dampers. The most frequent cure system used to cure AEM is a combination of HMDC (hexamethylenediamine carbamate) with DOTG (di-o-tolylguanidine) or DPG (diphenylguanidine). Previous studies show that hexamethylenediamine (HMDA), can replace HMDC in this type of cure system with similar cure and physical properties at a much lower cost. Advancure™ is a 47% active liquid concentrate of HMDA absorbed on amorphous silica in powder form. Advancure™ is based on patented curing technology from DuPont and is enhanced with an innovative dispersion technology from Chem Technologies.

The European Union under REACH will ban the use of guanidine accelerators such as DOTG and DPG due to carcinogenic concerns. Several chemical manufacturers have come up with alternative cure systems using HMDC and amine complexes to replace the guanidines. Since HMDC breaks down to HMDA during the curing of AEM it was theorized that HMDA would also work with the amine complexes.

This paper has a short review of previous HMDA/guanidine cure system studies and then focuses on new work that shows that HMDA can function well with the amine complexes in a guanidine-free cure system for curing AEM.