1. Overview of conductive rubber
1.1 Definition and characteristics
Conductive rubber is a special rubber material with high electrical conductivity. By adding conductive fillers (such as carbon black, metal powder, etc.) into the rubber matrix, the entire composite material has good conductivity.
When compared to regular rubber, conductive rubber boasts the following exceptional qualities:
- Possesses outstanding conductive qualities. The volume resistivity is capable of reaching 10-3-10-6 Ω·cm, which is sufficient for a wide range of conductive applications.
- It preserves the superior mechanical qualities of rubber, including its tensile strength, flexibility, and resistance to wear.
- It can successfully block electromagnetic radiation and has an excellent electromagnetic shielding effect.
- Antistatic: stops static energy from building up and exploding.
- Flexible manufacturing procedure that is simple to form and produce.
- The cost is comparatively little and appropriate for extensive uses.
1.2 Main components
- Rubber matrix: silicone, nitrile, natural rubber, and so on.
- Carbon black, conductive fiber, metal powder (copper, aluminum, silver, etc.), etc. are examples of conductive filler.
- Additional supporting materials: plasticizer, cross-linking agent, vulcanizing agent, etc.
To satisfy varied application demands, several varieties of conductive rubber may be made by varying the types and amounts of the materials listed above.
1.3 Manufacturing process
- Mixing: Combine the conductive filler, rubber matrix, and any auxiliary components thoroughly.
- Molding is the process of pressing or extruding a mixture into forms like sheets, profiles, etc.
- Vulcanization: To enhance the mechanical qualities, the molded pieces undergo high-temperature vulcanization and cross-linking.
- Post-processing: Ad hoc secondary processing, such bonding, cutting, etc.
2. Classification of conductive rubber
2.1 Classification according to conductive mechanism
2.1.1 Intrinsic conductivity type
When superior conductive polymer ingredients are directly incorporated into the rubber matrix, the result is conductive rubber that is intrinsically conductive. This class of material, which includes conductive polymers like polyphenylene and polypyrrole, has a high inherent conductivity. By means of conjugated bond electron leaping conduction, they are able to achieve the flow of current.
Although this kind of conductive rubber possesses strong antistatic and high electrical conductivity, its mechanical qualities are subpar, and its uses are restricted.
2.1.2 Doping conductivity type
Doped conductive rubber is made by incorporating conductive fillers into the rubber matrix and utilizing the fillers' conductive properties to make the entire composite material conductivity. Conductive fillers including conductive fiber, metal powder, and carbon black are frequently utilized.
This kind of conductive rubber has a high electrical conductivity, superior controllability, and the great mechanical qualities of rubber. This kind of conductive rubber is the most often utilized.
2.1.3 Mixed conductivity type
A conductive rubber with mixed conductivity type blends doped and inherent conductivity types.
It makes advantage of the superior conductivity of naturally conductive polymers and enhances the total conductivity with the addition of conductive fillers. This kind of conductive rubber performs exceptionally well overall and offers the benefits of both intrinsic and doped conductivity kinds.
The application is restricted, the cost is expensive, and the production process is complicated.
2.2 Classification by filler
2.2.1 Carbon filled type
Carbon black, carbon fiber, graphite, and other carbonaceous materials are used as conductive fillers in carbon-based filled conductive rubber. This kind of filler is inexpensive, simple to combine and distribute, and non-corrosive to the rubber matrix.
Products such as conductive carbon fiber rubber and conductive carbon black rubber are examples. Although this kind of conductive rubber is inexpensive and ideal for large-scale uses, its conductive qualities are often subpar.
2.2.2 Metal filled type
Metal powder (such as copper, aluminum, silver, etc.) is used as a conductive filler in metal-filled conductive rubber. Excellent electrical conductivity is a feature of metal materials, which can significantly increase total electrical conductivity.
Although the cost of this form of conductive rubber is costly and the rubber matrix is quickly corroded, it offers great electrical conductivity. Conductive copper powder rubber, conductive silver powder rubber, and other similar items are typical.
2.2.3 Other filling types
A tiny percentage of conductive rubbers also include alternative conducting fillers, such conductive ceramic powder, conductive fibers, etc., in addition to fillers based on metal and carbon.
Every one of these fillers has unique qualities, and you may choose the one that best suits the demands of your particular application. However, in general, there isn't much room for application.
3. Properties of conductive rubber
3.1 Conductive properties
The most significant performance metric for conductive rubber is conductivity. The following characteristics mostly represent conductivity:
- Volume resistivity may satisfy the needs of the majority of conductive applications; it is typically in the range of 10-3-10-6 Ω·cm.
- Surface resistance: Usually less than 106 Ω, it may successfully stop static electricity from building up.
- Effect of shielding: It has the ability to deflect electromagnetic radiation efficiently, with a 20–60 dB shielding effect.
- Conductive stability: The conductive performance varies slightly with variations in the surrounding temperature and humidity.
- The kind and concentration of the conductive filler and rubber matrix that are chosen determine the electrical conductivity quality.
Conductive rubber may be made to suit a variety of application requirements by refining the recipe and manufacturing procedure.
3.2 Mechanical properties
- Conductive rubber has outstanding mechanical qualities and great electrical conductivity.
- Tensile strength: typically between 2 and 10 MPa, which satisfies requirements for common process manufacturing and application.
- Elongation: Usually 100–500%, with strong deformation ability and flexibility.
- Hardness: Variable based on the needs of the application; typically falls between 30 and 90 Shore A.
- Wear resistance: Superior to regular rubber, appropriate for situations where wear resistance is needed.
The secret to guaranteeing the mechanical qualities of conductive rubber is to maintain reasonable control over the formula and process.
3.3 Environmental adaptability
- Unlike regular rubber, conductive rubber must satisfy certain environmental adaptation standards.
- Resistance to high and low temperatures: It can often tolerate temperatures between -40 and 150°C, and some unique items have the ability to exceed 60200°C.
- Chemical corrosion resistance: It is resistant to several substances, including oils, acids, and alkalis.
- Weather resistance: The ability to withstand aging caused by ozone, UV radiation, and other elements.
- Flame retardancy: The qualities of an additive, such as a flame retardant, can be enhanced.
4.Application fields of conductive rubber
4.1 Electronic and electrical industry
Conductive rubber is the most widely used in the electronic and electrical industry, mainly used for:
Electromagnetic shielding
Electrostatic discharge
Conductive connection
Touch switch, etc.
such as touch buttons, grounding gaskets, conductive seals, and the like in electronic devices like computers, TVs, and cell phones.
4.2 Military and aerospace fields
The following are some significant uses for conductive rubber in the aerospace and defense industries:
Electromagnetic shielding for radar and communication equipment
Electrostatic discharge and lightning strike protection
Spacecraft seals, etc.
It can satisfy the exacting standards in the aerospace and military industries for environmental adaptability and performance dependability.
4.3 Medical and health industry
Conductive rubber is widely used in the medical and health fields, mainly for:
Static electricity protection for medical equipment
Conductive floor mats in operating rooms
Conductive parts of rehabilitation equipment, etc.
It is frequently utilized in medical devices and rehabilitation equipment because to its strong biocompatibility and cleanability.
4.4 Other areas
In addition to the main applications mentioned above, conductive rubber is also widely used in:
Conductive grounding of power equipment
Electrostatic discharge and EMC protection in the automotive industry
Conductive flooring in the building decoration industry, etc.
5. Development trend of conductive rubber
5.1 Application of new fillers
New conductive fillers like graphene, carbon nanotubes, conductive polymers, etc. are gradually taking the place of traditional ones like metal powder, carbon black, etc. These novel fillers can further enhance the performance of conductive rubber since they have improved mechanical, electrical, and environmental adaptability.
5.2 Design of composite structures
The severe application settings of today can no longer be satisfied by a single conductive filler, and there has been a shift toward compounding numerous fillers. For instance, the combined usage of carbon nanotubes, carbon black, graphene, and metal powder may fully use the benefits of different fillers and create more effective conductive rubber.
5.3 Functional integration trend
The path of conductive rubber development is toward multifunctional integration. In addition to its exceptional conductivity, it also possesses additional properties including self-healing, shielding, and wave absorption. The intricate requirements of contemporary electronic equipment can be better met by this type of functional integration.
5.4 Improvement of environmental performance
Conductive rubber is evolving in the direction of environmental protection and degradability in tandem with the growing awareness of environmental protection. Future developments in conductive rubber will likely focus heavily on improving product recyclability through the use of ecologically friendly raw ingredients and manufacturing techniques.
