Silicone Rubber Gaskets  

Silicone Rubber (Si Rubber) is a synthetic rubber with a backbone structure dominated by silicon-oxygen (Si-O) bonds, with molecular side chains typically attached to organic groups such as methyl and vinyl. Its unique chemical structure endows the material with excellent resistance to high and low temperatures, weather resistance, electrical insulation, and biocompatibility. Therefore, silicone rubber gaskets are widely used in electronics, medical, food, automotive, and other fields with high requirements for performance diversity. The following is a detailed introduction covering core performance, typical application scenarios, advantages, and limitations: 

## I. Core Performance of Silicone Rubber Gaskets 

The molecular structure of silicone rubber is based on stable silicon-oxygen bonds, combining the stability of inorganic materials with the elasticity of organic materials. Its specific performance characteristics are as follows: 

### 1. Resistance to High and Low Temperatures 

- **Extremely wide temperature range**: It can work stably for a long time in the range of **-60℃~200℃**. Some high-performance grades (such as addition-crosslinked silicone rubber) can withstand short-term temperatures up to 250℃, and even maintain elasticity at around -100℃ in low-temperature environments. It is one of the few rubber materials that can adapt to both extreme high and low-temperature conditions. 

- **Stability at extreme temperatures**: It is not prone to decomposition, hardening, or flowing at high temperatures, nor to embrittlement or loss of elasticity at low temperatures. It has a low compression set rate (usually <25% after long-term high-temperature use), ensuring continuous sealing performance in working conditions with drastic temperature fluctuations. 

### 2. Weather Resistance and Anti-Aging Properties 

- **Excellent resistance to natural aging**: It has strong resistance to oxygen, ozone, ultraviolet rays, direct sunlight, and climate changes (such as rain, humidity, and temperature alternations). When exposed to outdoor environments for a long time, it is not prone to cracking, yellowing, or performance attenuation, and its service life is much longer than that of ordinary rubbers (such as natural rubber and nitrile rubber). 

- **Chemical inertness**: It has good tolerance to water, steam, weak acids and alkalis (such as dilute hydrochloric acid and dilute sodium hydroxide solutions), and most food-grade cleaning agents, and is not prone to swelling or degradation. 

### 3. Electrical Insulation Performance 

- **High insulation strength**: Its volume resistivity can reach 10¹⁴~10¹⁶ Ω·cm, with a low dielectric constant (usually 3.0~3.5) and a small dielectric loss tangent. It maintains stable insulation performance even in high-frequency and high-voltage environments, making it an ideal material for sealing and insulation in the electronic and electrical fields. 

- **Arc and corona resistance**: It can withstand short-term arc discharge and corona effects, and is not prone to performance failure due to electrical aging. 

### 4. Biocompatibility and Safety  

- **Non-toxic and odorless**: It meets multiple safety certifications such as FDA (U.S. Food and Drug Administration), USP (U.S. Pharmacopeia), and LFGB (German standards for food contact materials). It is non-irritating when in contact with human skin and mucous membranes and does not release harmful substances. 

- **Sterilization resistance**: It can withstand common medical sterilization methods such as high-temperature steam sterilization (121℃~134℃), ultraviolet sterilization, and gamma-ray sterilization, with basically unchanged performance after sterilization. 

### 5. Physical and Mechanical Properties  

- **Elasticity and flexibility**: It has excellent elasticity and compression rebound. Even after long-term compression, it can quickly return to its original shape, ensuring tight fitting of the sealing surface and reducing the risk of leakage. 

- **Resistance to compression set**: Under high-temperature or long-term stress conditions, its shape retention ability is better than that of most general-purpose rubbers, making it particularly suitable for scenarios requiring long-term static sealing. 

## II. Typical Application Scenarios of Silicone Rubber Gaskets  

Based on the above performance characteristics, silicone rubber gaskets are widely used in fields with prominent requirements for high and low-temperature resistance, safety, insulation, or weather resistance: 

### 1. Electronics and Electrical Industry 

- **Sealing of electronic devices**: Used for waterproof and dustproof sealing of smartphones, laptops, sensors, and other devices, adapting to temperature fluctuations during equipment operation (such as high temperatures generated by chip heat dissipation). 

- **Electrical insulation components**: As sealing gaskets for transformers, insulators, and cable joints, they provide both insulation and temperature resistance, resisting the impact of humid environments on electrical performance. 

- **LED lighting equipment**: Adapted for sealing heat dissipation components of LED lamps, withstanding high temperatures (60℃~150℃) during LED chip operation and outdoor climate aging. 

### 2. Medical and Pharmaceutical Industry 

- **Sealing of medical equipment**: Used as seals for medical devices such as infusion pumps, ventilators, and sterilizers, meeting requirements for biocompatibility, non-toxicity, and sterilization resistance to ensure equipment cleanliness and safety. 

- **Medical consumables**: As interface gaskets for medical devices (such as syringe pistons and infusion tube seals), they have no adverse reactions when in contact with medicinal liquids or human tissues. 

- **Pharmaceutical equipment**: Used for sealing reactors and pipeline flanges in pharmaceutical production, withstanding high-temperature steam sterilization and cleaning agent flushing without contaminating drugs. 

### 3. Food and Beverage Industry  

- **Food processing equipment**: Adapted for sealing sterilizers, fermenters, and filling machines, complying with food contact safety standards and resisting erosion from high-temperature steam, acid-alkali cleaning agents, and food raw materials (such as oils and fruit juices). 

- **Kitchen appliance sealing**: Used for sealing doors or pipelines of household appliances such as microwave ovens, coffee machines, and ovens, withstanding high temperatures (100℃~200℃) and water vapor erosion during cooking. 

### 4. Automotive and Transportation 

- **Automotive electrical systems**: Used for sealing sensors and wire harness connectors in engine compartments, adapting to high engine temperatures (100℃~180℃) and vibration environments while providing insulation protection. 

- **New energy vehicles**: Adapted for waterproof sealing of battery packs and motor controllers, withstanding temperature fluctuations (-40℃~85℃) during battery operation and erosion from coolants (such as ethylene glycol solutions). 

- **Automotive air conditioning systems**: As sealing gaskets for air conditioning pipelines or valves, resisting refrigerants (such as R134a) and high-low temperature cycle impacts. 

### 5. Outdoor and Industrial Equipment  

- **Sealing of outdoor facilities**: Used for sealing solar panel frames and communication base station enclosures, resisting harsh outdoor environments such as ultraviolet rays, rain and snow, and high-low temperature alternations. 

- **Industrial ovens and furnaces**: As door sealing gaskets for high-temperature equipment, withstanding continuous high temperatures (150℃~200℃) and thermal cycle impacts. 

## III. Advantages and Limitations of Silicone Rubber Gaskets  

### Advantages 

- **Extremely wide high and low-temperature resistance range**: Can be used long-term at -60℃~200℃, adapting to extreme temperature scenarios, far exceeding most rubber materials; 

- **Excellent weather resistance and long service life**: Superior ozone and ultraviolet resistance, not prone to aging in outdoor or long-term use, with low maintenance costs; 

- **High biocompatibility and safety**: Non-toxic and odorless, meeting food and medical-grade standards, suitable for scenarios in contact with humans or food; 

- **Excellent electrical insulation performance**: High insulation strength, adapting to sealing and insulation needs of electronic and electrical equipment; 

- **Good elasticity and rebound**: Maintains sealing effect after long-term compression, suitable for static sealing working conditions. 

### Limitations  

- **Limited chemical resistance**: Poor tolerance to strong acids and alkalis (such as concentrated hydrochloric acid and concentrated nitric acid) and organic solvents (such as gasoline and ketones), prone to swelling or degradation; 

- **Low mechanical strength**: Tensile strength, tear strength, and wear resistance are inferior to FKM, nitrile rubber, etc., not suitable for high mechanical stress or friction working conditions; 

- **Higher cost than general-purpose rubber**: More expensive than natural rubber, EPDM, etc., with slightly lower cost performance in non-essential scenarios; 

- **High gas permeability**: Poor barrier properties to gases (such as oxygen and nitrogen), not suitable for scenarios requiring high vacuum or high airtightness.