EPDM rubber, or ethylene propylene means Ethylene Propylene Diene Monomer, it is a synthetic elastomer material that is well-known due to its unique properties of excellent weathering, ozone, heat, and chemicals.
However, the EPDM raw material can’t be used directly before the process of vulcanization or curing .
Curing or vulcanization for EPDM is the chemical process of transforming the raw rubber material into a solid, the curing process involves cross-linking the long chains of EPDM polymer molecules using a curing agent,accelerator or other sulfur (e.g., MBTS, TMTD, zinc oxide).
In this blog, we’ll dive into what curing means for EPDM rubber, how it’s done, and why it’s crucial for achieving durability, flexibility, and functionality in the final product.
What Is Curing in EPDM Rubber?
Curing is a chemical process that This cross-linking transforms soft, tacky, and thermoplastic raw rubber into a durable, elastic, and thermoset material with the mechanical and chemical properties required for its intended application.
Curing Systems for EPDM Rubber
There are two primary curing systems used for EPDM:
1. Sulfur Cure:
Sulfur cure is a widely used EPDM rubber curing process. This curing process involves mixing the raw rubber material with sulfur as curing agent. The sulfur cure process requires a lower curing temperature and has a shorter curing time than peroxide cure, which results in lower mechanical properties and heat resistance.
Sulfur curing process provides good mechanical properties such as tensile strength and elongation.
2. Peroxide-Based Curing
Peroxide Cure: Peroxide cure is very common EPDM rubber curing process. The peroxide chemicals act as a catalyst, initiating the cross-linking of the rubber molecules. This peroxide curing process requires higher temperature and takes a longer curing time, but it results in excellent mechanical properties and heat resistance.
Peroxide cured EPDM is generally considered “cleaner” and does not bloom ,it offer excellent heat aging and compression set resistanceis and better used for high-performance and weather-resistant applications.
So peroxide cured EPDM is widely used in automotive seals, weatherstrips,electrical, and consumer goods and roofing membranes industries.
So How Does The Curing Process Work?
1. Formulation
The EPDM compound is mixed with fillers (e.g., carbon black), oils, and the curing system (sulfur or peroxide) using an internal mixer or two-roll mill machine .
2. Shaping/Forming
The EPDM compound material is then shaped through extrusion, compression press equipment or other machine ,which depend on your specific needs.
3. Curing (Vulcanization)
After shaping from the extrusion machine or two roll mill ,the compound material is then need to heat, usually between 160°C to 200°C. Under some time and temperature ,this vulcanization begins the cross-linking process.
The Benefits of EPDM Curing
* Improved Elasticity: Through the process of curing , it enables EPDM raw material to stretch and return to shape.
* Heat Resistance: The curing process enhances EPDM material chemical and thermal stability , the cured EPDM material can withstand long-term heat exposure.
* Weather & Ozone Resistance: Crucial for outdoor and automotive parts.
* Chemical Stability: Enhances resistance to acids, alkalis, and other corrosive agents.
* Mechanical Strength: Increases tensile strength and abrasion resistance.
In conclusion , curing is not just a simple process —it’s a transformation. No matter you utilize sulfur or peroxide curing way, the curing process defines the final performance of EPDM rubber products. Thus ,for manufacturers or factories, cured EPDM is critical for product longevity, compliance, and reliability.
Are you in the need of help optimizing your EPDM rubber processing or selecting the right curing system? Contact our technical team today for expert support and equipment recommendations.