Low Volatility Plasticizers for AEM Compounds

Most AEM compounds use a plasticizer and the type and amount of the plasticizer has a major impact on compound properties.  The heat aging requirements for AEM compounds continue to increase in time and/or temperature and there have been heat aging issues that are due to the plasticizers.  Some of the traditional plasticizers used for AEM compounds do not heat age as well as the other ingredients in an AEM compound.    

Several low volatility plasticizers have been evaluated in AEM compounds and they improve the heat aging properties.  Another benefit is that the compounds have significantly better low temperature properties after heat aging in air.  Compression set of AEM compounds with these plasticizers is improved especially as the test times and test temperatures are increased.  Some AEM compounds still use DOTG as the accelerator because it provides good compression set.  Replacing the traditional plasticizers with the low volatility plasticizers may allow DOTG free compounds to meet the compression set requirements.  For hose compounds, the low volatility plasticizers provide a better balance of compression set and dynamic properties.  Another benefit is that there is less weight loss in the post cure step which leads to lower deposits in the post cure oven and lower emissions of VOC’s.