NEWMARKET, Ontario—Three years ago, chemists and some officials within AirBoss of America Corp.'s Rubber Solutions division set out on a quest to develop a new, cost effective formulation to replace more expensive materials that reduce heat in automotive muffler hanger applications.
Their search ended with the recent development of HeatBoss EPDM, a next-generation, high heat-resistant compound that's prepared by novel formulation design using EPDM monomer with a selected third diene monomer and peroxide cure system, according to George Papazotos, vice president of sales and product development for Rubber Solutions, and Steven Yu, vice president of compound technology for the division.
"We were looking for a formulation that rivals silicone, but is more cost effective," said Papazotos, who helped kick off the project to develop the new rubber compound. He also will present a paper on the new formulation at the Rubber in Automotive Conference, organized by Rubber & Plastics News, to be held virtually June 1-3.
The paper was prepared by Yu, Ali Vahidifar, a research and development chemist, and Eknaz Esmizadeh, a research and development engineer and rubber chemist.
Papazotos noted in an interview that the compound is an excellent alternative for use in muffler hanger applications, adding that the product will be ready for the market by the time he makes his presentation in June.
Vahidifar, Esmizadeh and Yu said in their paper that the HeatBoss formulation demonstrates superior heat resistance to that of normal EPDM compounds, cured by either sulfur or peroxide.
"Our HeatBoss EPDM, after being aged at 350°F for 672 hours, shows only 53 percent loss in elongation at break, 18 percent in tensile strength, along with seven points increase in hardness," they stated.
"This means that this performance is comparable to that of a typical silicone rubber used in automotive muffler hanger applications, which shows a loss of 54 percent in elongation, 20 percent in tensile and seven points increase in hardness."
However, they said the HeatBoss formulation had better initial dynamic and mechanical properties than silicone.
Their study shows that HeatBoss EPDM can match the performance of silicone after aging. "FTIR (Fourier Transform Infrared Spectroscopy) and microscopes were used to investigate the physical and chemical change, if any, of the aged HeatBoss EPDM surface," according to Yu.
Results showed there was no noticeable crack or craze formation, and a minor change in the chemical structure of the surface was spotted after aging, he said, which demonstrated that HeatBoss EPDM has excellent resistance to ozone and oxygen attack at elevated temperatures.
"Such excellent heat-aging performance has qualified our HeatBoss EPDM for type E applications per J200 or ASTM D2000," the authors noted. In addition, they said HeatBoss can be formulated to possess similar processability as silicone, but at a 50 to 60 percent lower cost, which makes it an ideal alternative as a replacement for silicone in muffler hanger and potentially other applications that require Grade E elastomers.