The deformation size of vulcanized rubber compression, involving its elasticity and recovery, is often misunderstood. People tend to believe that good elasticity equals quick recovery and less deformation, but this is not entirely accurate. The deformation size is primarily governed by the rubber's recovery ability. Factors affecting recovery include intermolecular forces (viscosity), changes or destruction of the network structure, and molecular displacement. When rubber deformation is caused by the stretching of molecular chains, its recovery (or deformation size) is mainly determined by the rubber's elasticity. If the deformation is accompanied by network destruction and relative flow of molecular chains, this part is considered non-recoverable and unrelated to elasticity. Therefore, any factors affecting rubber elasticity and recovery are also factors influencing the compression deformation of vulcanized rubber.

Based on data support from SGS material laboratory engineers, general soft foam materials (such as rubber, sponge products) require testing of compression deformation parameters. Under the same testing conditions, the smaller the CS, the better the material's resilience and the stronger its resistance to deformation. Due to various corresponding standards, different laboratories and product requirements may adopt different standards and calculation formulas.

Principle

Compress the specimen of known height to the specified height according to the compression ratio requirements, maintain it at the specified temperature for a certain period, then release the compression, allow the specimen to recover in a free state, and measure the height of the specimen.

Test Program

The sample should be treated for 24 hours under conditions of (23±2)℃，(50±5)%RH.

2. Measure the original thickness of the sample to 0.02mm.

3. Place the sample into the instrument, insert the appropriate pad for the sample type, and secure the instrument. This can be done at room temperature.

4. After mounting the specimen, it must be placed in the pre-set temperature oven within 2 hours.

Reference temperatures and times for testing are provided in standards such as ASTM D1349-99, including: -75°C, -55°C, -40°C, -25°C, -10°C, 0°C, 23°C, 40°C, 55°C, 70°C, 85°C, 100°C, 125°C, 135°C, 150°C, 160°C, 175°C, 200°C, 225°C, 250°C.

Testing time is 22h and 70h (SGS in-house method).

After the test time has ended, immediately remove the instrument from the oven and detach the sample.

Place the sample on a wooden board or poor thermal conductor and cool it under conditions of (23±2)℃ and (50±5)%RH.

6. Measure the sample's thickness again after cooling for 30 minutes.

Result Calculation

C = [(To-Ti)/(To-Tn)] X100

Compressed deformation, %

Tn -垫块厚度, mm

To——Sample Thickness Prior to Testing, mm

Ti - Sample thickness after testing, mm