The key difference between sulfur and peroxide cure is that sulfur cured EPDM shows low chemical and thermal resistance compared to the peroxide cured EPDM.
The term EPDM stands for Ethylene Propylene Diene Monomers. It is a type of high-density synthetic rubber. Generally, this material is not heat resistant compared to materials such as silicone, but it can withstand high temperatures that are up to about 130 Celsius degrees. Therefore, we can do sulfur curing and peroxide curing to enhance this property of chemical and thermal resistance.
CONTENTS
1. Overview and Key Difference
2. What is Sulfur Cure
3. What is Peroxide Cure
4. Side by Side Comparison – Sulfur vs Peroxide Cure in Tabular Form
5. Summary
What is Sulfur Cure?
Sulfur is a chemical element having the chemical symbol S and atomic number 32. It is a polyatomic nonmetal having the electron configuration [Ne]3s23p4. This is an abundant, multivalent, and nonmetallic chemical substance that occurs in two major forms as organic sulfur and inorganic sulfur. We can use this nonmetal for the production of sulfur cured EPDM.
Figure 01: Chemical structure of EPDM
EPDM or Ethylene Propylene Diene Monomer is a popular and versatile rubber compound that is commercially available. The most concerning properties of EPDM are outstanding heat, ozone, and weather resistance. We can subject this material to curing with either sulfur or peroxide. Here, we need to choose the proper material and method for curing based on the end-use and its application.
Generally, sulfur cured EPDM is common and readily available compared to peroxide cured EPDM. Moreover, this material is generally more commercially attractive. However, it can withstand temperatures up to about 250 degrees Fahrenheit, which is comparatively a low value. Furthermore, sulfur cured EPDM is higher in tensile strength, has a high tear strength, and permits us to use it in a wide range of fillers.
What is Peroxide Cure?
Peroxide is a reactive chemical species in which two oxygen atoms are linked together with a single covalent bond. There are several peroxides that are common as bleaching agents. We can use peroxides to get peroxide cured EPDM.
In general, EPDM that is cured with peroxide has a superior chemical and thermal resistance compared to sulfur cured EPDM. The peroxide cured EPDM is able to withstand temperatures up to 300 degrees Fahrenheit. Moreover, it can improve the compression set and ageing resistance of the material.
Furthermore, peroxide cured EPDM has high-temperature resistance, good resistance to ageing, low compression set, improved resistance to chemicals and oils, and it will not stain metals or PVC.
What is the Difference Between Sulfur and Peroxide Cure?
We can do sulfur curing and peroxide curing to enhance the properties of EPDM by increasing chemical and thermal resistance. The key difference between sulfur and peroxide cure is that sulfur cured EPDM shows low chemical and thermal resistance compared to peroxide cured EPDM. Moreover, sulfur cured EPDM has high tensile strength, high tear strength, and permits us to use it in a wide range of fillers while peroxide cured EPDM has high-temperature resistance, good resistance to ageing, low compression set, improved resistance to chemicals and oils, and it is will not stain metals of PVC.
Below is a summary of the difference between sulfur and peroxide cure in tabular form.
Summary – Sulfur vs Peroxide Cure
The term EPDM stands for Ethylene Propylene Diene Monomers. It has a low thermal resistance, so we need to cure it to enhance its properties. We use sulfur curing and peroxide curing to enhance this property of chemical and thermal resistance. The key difference between sulfur and peroxide cure is that sulfur cured EPDM shows low chemical and thermal resistance compared to the peroxide cured EPDM.
Reference:
1. “Peroxide or Sulphur Cured EPDM – What Does Your Application Need?” Rocket Seals, Inc., Available here.
Image Courtesy:
1. “EPDM copolymer” By Doxepine – Own work (Public Domain) via Commons Wikimedia