Seven Physical Properties of Silicone Rubber

- May 06, 2020-

Products used in life, including household appliances, kitchen supplies, and electronic products, all use silicone rubber products as accessories. Today, ES silicone is about what physical properties make silicone rubber products so popular.

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1. Viscosity. Viscosity refers to the volumetric characteristics of liquids, pseudo-liquids or pseudo-solids that resist flow, that is, the internal friction or internal resistance between molecules when flowing under the action of external forces. Normally, viscosity and hardness are proportional.


2. Hardness. The ability of a material to locally resist the pressing of hard objects into its surface is called hardness. Silicone rubber has a Shore hardness range of 10 to 80, which gives designers full freedom to choose the required hardness to best achieve a specific function. Various intermediate hardness values can be achieved by mixing polymer substrates, fillers and additives in different proportions. Similarly, the time and temperature of heat curing can also change the hardness without destroying other physical characteristics.


3. Tensile strength. Tensile strength refers to the force required per unit of range to cause a piece of rubber material to tear. The hot-vulcanized solid silicone rubber tensile strength range is between 4.0-12.5MPa. The tensile strength of fluorosilicone rubber is between 8.7-12.1MPa. The tensile strength of liquid silicone rubber ranges from 3.6-11.0MPa.


4. Tear strength. The resistance to the expansion of the incision or score when a force is applied to the sample with the incision. Even after being cut and placed under extremely high torsional stress, the thermally vulcanized solid silicone rubber will not be torn. The hot vulcanized solid silicone rubber has a tear strength range of 9-55 kN / m. The tear strength of fluorosilicone rubber ranges from 17.5-46.4 kN / m. The tear strength of liquid silicone rubber ranges from 11.5-52 kN / m.


5. Elongation. It usually refers to the "limit elongation at break" or the percentage of increase relative to the original length when the sample breaks. Hot vulcanized solid silicone rubber generally has an elongation range of 90 to 1120%. The elongation of fluorosilicone rubber is generally between 159 and 699%. The general elongation of liquid silicone rubber is between 220 and 900%. Different processing methods and choice of hardener can greatly change its elongation. The elongation of silicone rubber has a great relationship with temperature.


6. Operating time. The operating time is calculated from the moment the colloid is added to the curing agent. There is no complete limit between this operating time and the later curing time. The colloid has already undergone the curing reaction from the moment the curing agent is added. This operating time means that the 30-minute curing reaction of the product does not affect the quality of the finished product. Therefore, the more time saved during the operation of the product, the more beneficial it is to the finished product.


7. Vulcanization time. In some places, it is said to be the curing time. In other words, after such a long time, the vulcanization reaction of silica gel is basically over. This is basically over, which means that the product is already available, but in fact there is still a small part of the curing reaction has not yet ended. Therefore, products made of silicone rubber, such as silicone molds, are usually put in use for a period of time.