Ethylene propylene diene monomer (EPDM), also known as ethylene-propylene-diene monomer rubber, is an important synthetic material in the rubber industry. It is copolymerized from ethylene, propylene and a small amount of non-conjugated dienes, and has a unique chemical structure and excellent physical properties. This article will deeply explore the main properties of ethylene propylene diene monomer (EPDM) rubber and its improvement methods.
I. Main Properties of Ethylene Propylene Diene Monomer Rubber
1. Aging resistance
The main chain of EPDM rubber is composed of chemically stable saturated hydrocarbons, with only unsaturated double bonds in the side chains. This structure endows it with outstanding oxidation resistance, ozone resistance and erosion resistance. Therefore, EPDM rubber products can maintain good performance stability even in harsh environments and are widely used in outdoor construction, automotive parts and other fields.
2. Heat resistance
Due to the stability of its molecular structure, EPDM rubber is not prone to thermal degradation at high temperatures and can work for a long time at relatively high temperatures. For instance, in the wire and cable industry, peroxide-cross-linked EPDM rubber exhibits higher temperature resistance and is suitable as an insulating material in high-temperature environments.
3. Corrosion resistance
EPDM rubber has good resistance to a variety of polar chemicals such as alcohols, acids and alkalis, but its stability to aliphatic and aromatic solvents is relatively poor. This characteristic enables EPDM rubber to be widely applied in fields such as chemical equipment and pipelines.
4. Low density and high filling property
EPDM rubber has a relatively low density and can absorb a large amount of fillers and oil, which helps to reduce the cost of products. The physical and mechanical properties of EPDM rubber products after high filling do not decrease significantly, so they have significant economic advantages in many applications.
5. Electrical insulation
EPDM rubber has excellent electrical insulation performance and corona resistance. Its electrical properties are superior to or close to those of many other rubber materials, making it suitable for applications with high requirements for electrical performance.
Ii. Improvement Methods for Ethylene Propylene Diene Monomer Rubber
Optimization of the vulcanization system
EPDM rubber can be vulcanized using various vulcanization systems such as sulfur, peroxides, quinone oxime or resins. Different vulcanization systems have a significant influence on the physical and mechanical properties of rubber. For example, the sulfur-accelerator system has a relatively fast vulcanization rate and good physical and mechanical properties; The peroxide vulcanization system, on the other hand, has better heat resistance and compression set performance. By choosing the appropriate vulcanization system and optimizing the vulcanization conditions, the performance of EPDM rubber can be significantly improved.
2. Enhance adhesion
The molecular structure of EPDM rubber lacks active groups and has poor self-adhesiveness and mutual adhesiveness. To improve this problem, the following methods can be adopted:
Used in combination with rubber with good self-adhesiveness (such as natural rubber);
Use tackifying resin;
Avoid using additives that are prone to causing blooming (such as degrading agents, oils, paraffin, etc.);
Appropriately reduce the rubber mixing temperature or adopt a two-stage mixing process.
3. Improve processing performance
During the processing of EPDM rubber, its processing performance can be improved by adjusting the ethylene-propylene ratio, molecular weight and its distribution. For example, increasing the ethylene content can enhance the tensile strength and the strength of the green billet. Increasing the propylene content is beneficial to improving the low-temperature characteristics and compressive deformation. In addition, the selection of appropriate catalyst and co-catalyst types and concentrations also has a significant impact on processing performance.
4. Reduce costs
Due to the relatively high price of raw EPDM rubber, the following methods can be adopted to reduce costs:
Increase the dosage of fillers and rubber oil;
Use waste rubber resources (such as EPDM reclaimed rubber) to replace part of the raw rubber;
Used in combination with other low-cost rubbers (such as butyl rubber, natural rubber, etc.).
Iii. Summary
Ethylene propylene diene monomer (EPDM) rubber holds an important position in the rubber industry due to its unique chemical structure and excellent physical properties. By continuously optimizing the vulcanization system, enhancing adhesion, improving processing performance and reducing costs, the performance and application value of EPDM rubber can be further enhanced. With the continuous development of science and technology, it is believed that more innovative technologies and methods will be applied to the improvement of EPDM rubber in the future, promoting its application and development in a wider range of fields.