# Chemical Stability and Leaching Behavior of ECO EPDM in Acidic Fuel Cell-like Conditions

## TL;DR

This study compares the durability of two eco-friendly EPDM materials in acidic fuel cell conditions, finding that circular carbon black-filled EPDM performs better over time.

## Contribution

The study introduces a comparison of circular and recycled carbon black-filled EPDM materials under PEMFC-like conditions, highlighting the superior stability of circular carbon black-filled EPDM.

## Key findings

- CCB-filled EPDM showed lower leaching and better surface preservation than RCB-filled EPDM in acidic environments.
- HPLC analysis revealed CCB EPDM had higher organic leaching only under strong acid exposure.
- SEM imaging confirmed greater surface damage in RCB EPDM compared to CCB EPDM.

## Abstract

This study investigates the chemical stability and leaching behavior of two environmentally sustainable EPDM elastomers filled with circular carbon black (CCB) and recycled carbon black (RCB) when exposed to acidic, fuel cell-like environments. Accelerated aging tests were conducted in sulfuric acid solutions of varying concentrations (1 M, 0.1 M, and 0.001 M) at 90 °C for 1000 h to simulate long-term degradation in proton exchange membrane fuel cell (PEMFC) sealing applications. Complementary hot water extraction tests (HWET) were performed at 80 °C for up to 168 h to evaluate ionic leaching via conductivity measurements. HPLC-DAD analysis was used to assess organic leachates, while surface changes were examined by SEM and thermal transitions by DSC. Results revealed lower leaching and improved surface preservation in the CCB-filled EPDM, which remained below the critical 5 µS/cm ionic conductivity threshold for longer durations than its RCB counterpart. HPLC results showed filler-dependent trends in organic compound release, with CCB EPDM exhibiting higher leaching only under strong acid exposure. SEM confirmed greater surface damage and porosity in RCB EPDM. Overall, both materials demonstrated adequate chemical resistance, but the CCB formulation exhibited superior long-term stability, supporting its use in sustainable PEMFC sealing applications.