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Published on January 1, 2005

Improving Processability with low Mooney HNBR for Automotive Applications

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Date Published January 1, 2005

This Report has been authored by:Salvatore J. Monte at Kenrich Petrochemicals Inc.

Hydrogenated acrylonitrile-butadiene rubber (HNBR) is a high performance specialty elastomer that is used in a diverse array of automotive applications (seals, gaskets, o-rings, hose, timing belts) due to its unique combination of heat (up to 150°C) and oil resistance together with its excellent mechanical and dynamic properties. In order to enhance general processability characteristics of HNBR, a new low viscosity HNBR has recently been developed. Known as HNBR-AT (Advanced Technology), it possesses an acrylonitrile (ACN) content of 34 wt%, a 39 Mooney viscosity (ML 1+4@100°C) and < 0.9% residual double bond (RDB) content. This grade was specifically designed for improved processability meaning easier mixing and quicker cycle times during extrusion as well as injection, transfer and compression molding. Besides being used alone, HNBR-AT is a perfect candidate to improve the processing characteristics of higher viscosity HNBRs. The object of this work is to test this hypothesis and to incorporate ACN and RDB variation into the blended HNBRs in order to assss property and aging effects as well. The results clearly illustrated processing improvement by using low viscosity HNBR in the blends. Enhanced aging resistance against heat and oils was observed when HNBR-AT was blended with a higher RDB HNBR. Lower overall ACN level HNBR blends provided better low temperature properties and slightly higher but tolerable volume swells in the oils tested. The study results suggest the use of HNBR-AT to improve processability, and general properties of current functioning HNBR compounds.