Difference between plastic seals and rubber seals
Plastic seals and rubber seals are commonly used sealing components in the industrial field. They play an important role in ensuring the normal operation of equipment, reducing leakage, and improving efficiency. However, due to different material properties and application environments, there are some differences in performance and use occasions between plastic seals and rubber seals.
Differences in material properties
plastic seal
Plastic seals are usually made of different types of plastic materials, such as polypropylene (PP), polytetrafluoroethylene (PTFE), polyurethane (PU), etc.
Plastic materials usually have good corrosion resistance, low water absorption, excellent mechanical strength and wear resistance.
Certain plastics such as PTFE have excellent chemical resistance and low friction coefficient, and are suitable for high temperature, high pressure and highly corrosive media environments.
Plastic seals may not be as flexible as rubber seals and therefore may not be the best choice in some applications where higher elasticity is required.
| PP Polypropylene (PP)physical information | |||
| Physical properties | Rating (metric) | Rating (imperial) | Test Methods |
| density | 0.920 g/cc | 0.0332 lb/in³ | ISO 1183 |
| Saturated water absorption | 0.10% | 0.10% | ISO 62 |
| Mechanical behavior | Rating (metric) | Rating (imperial) | Test Methods |
| Shore Hardness (Shore D) | 70 | 70 | ISO 868 |
| ultimate tensile strength | 29.4MPa | 4270 psi | ISO 527 |
| Elongation (breaking) | >= 50% | >= 50% | ISO 527 |
| Tensile modulus | 1.25 GPa | 181 ksi | ISO 527 |
| Notched impact strength of cantilever beams | 7.00kJ/m² | 3.33 ft-lb/in² | ISO 180 |
| Electrical properties | Rating (metric) | Rating (imperial) | Test Methods |
| Dielectric strength | 55.0kV/mm | 1400kV/in | ISO 60243 |
| Thermal properties | Rating (metric) | Rating (imperial) | Test Methods |
| linear thermal expansion coefficient | 160 µm/m-°C | 88.9 µin/in-°F | ISO 11359 |
| Maximum operating temperature, Air | 100°C | 212°F | continuous |
| Minimum operating temperature, Air | 5.00°C | 41.0°F | |
Rubber seal
Rubber seals are made of natural rubber or synthetic rubber, such as fluorine rubber (FKM), silicone rubber (VMQ), nitrile rubber (NBR), etc.
Rubber material has good elasticity, flexibility and sealing properties, and can adapt to various shapes of sealing surfaces.
Rubber seals can withstand large tensile and compressive deformations and are suitable for dynamic sealing and situations requiring better buffering performance.
The resistance of a rubber material to temperature and chemical media depends on its type and formulation, and some rubbers have good resistance to specific chemicals.
| Physical property information: | Ozone resistance | HNBR | |
| Basic Information | Good chemical resistance | ||
| Characteristic | Good wear resistance Good weather resistance Heat resistance, high Oil resistance |
||
| Use | Marine applications;Oil/Gas Supplies | ||
| Agency rating | ASTM D 2000 black | ||
| Exterior | Rating | ||
| Hardness | 70 | Test Methods | |
| IRHD hardness | Rating | unit system | ASTM D1415, ISO 48 |
| Elastomer | 16.3 | MPa | Test Methods |
| Tensile Strength (Yield) | 250 | % | ASTM D412, ISO 37 |
| Elongation (breaking) | 12 | % | ASTM D412, ISO 37 |
| Compression set (135°C, 24 hr) | Rating | unit system | ASTM D395, ISO 815 |
| Ageing | 10 | % | Test Methods |
| Rate of change of tensile strength in air (150°C, 70 hr) | -10 | % | ASTM D412, ISO 37 |
| Rate of change of ultimate elongation in air (150°C, 70 hr) | 3 | ASTM D412, ISO 37 | |
| Rate of change of IRHD hardness in air (150°C, 70 hr) | Rating | unit system | ASTM D573, ISO 188 |
| Thermal properties | 180 | °C | |
| Maximum Operating Temperature | Rating | unit system | |
| Additional information | -30 | °C | |
| Low Temperature Resistance - Non Brittle after 3 mins | |||
| Minimum Operating Temperature (Static): -40°C (-40°F)Minimum Operating Temperature (Dynamic): -30°C (-22°F) | |||
Differences in application environment
plastic seal
Plastic seals are suitable for general industrial environments, especially where corrosion resistance, low friction and wear resistance are required.
Due to the better thermal stability of plastic materials, plastic seals can be used at higher temperatures, but are generally not as resistant to high temperatures as rubber seals.
Plastic seals perform well in high-pressure and high-load applications, but can become brittle in low-temperature environments.
Rubber seal
Rubber seals are suitable for applications requiring good sealing and elasticity, such as dynamic sealing and applications in vibration environments.
Rubber seals can operate over a wide temperature range, and some special rubbers such as silicone rubber can be used in extreme temperatures.
Rubber seals are highly resistant to chemicals and are suitable for environments in contact with oils, solvents and other corrosive media.
Performance and lifespan differences
plastic seal
Plastic seals generally have a longer life because they are less susceptible to oxidation and corrosion.
The hardness and wear resistance of plastic materials allow plastic seals to have better wear resistance in high pressure and high speed applications.
Rubber seal
The life of rubber seals can be affected by factors such as temperature, pressure, chemicals and UV rays.
Rubber materials may age due to long-term exposure to extreme environments, resulting in performance degradation.
To sum up, plastic seals and rubber seals each have their own advantages and applicable scenarios. When selecting seals, the specific operating environment, performance requirements, and cost considerations determine which type of seal to use.
