Curing Mechanism

• Addition-type: It cures through the hydrosilylation reaction. Usually, a siloxane containing vinyl groups reacts with a hydrosiloxane through an addition reaction under the action of a platinum catalyst to form a cross-linked structure. There are no small molecular by-products generated during the curing process.
• Condensation-type: It relies on the condensation reaction between silanol groups and other active groups (such as alkoxy groups, acetoxy groups, etc.) to achieve curing. Small molecular by-products (such as water, alcohol, etc.) will be generated during the curing process.

Performance Characteristics

• Addition-type
  • Curing Speed: The curing speed is relatively fast. The curing time can be precisely controlled by adjusting the amount of the catalyst and other methods, which can meet the needs of rapid production.
  • Mechanical Properties: After curing, it has good mechanical strength, flexibility and abrasion resistance, and can maintain stable performance in different environments.
  • Heat Resistance: Generally, it has good heat resistance and can be used at high temperatures for a long time. Some products can withstand temperatures above 200°C.
  • Electrical Properties: It has excellent electrical insulation properties, with a low dielectric constant and a low tangent of the dielectric loss angle, and can be used in the fields of electronics and electricity with high insulation requirements.
  • Shrinkage Rate: The curing shrinkage rate is small, which enables precise molding and is very beneficial for some applications with high requirements for dimensional accuracy.
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• Condensation-type
  • Curing Speed: The curing speed is relatively slow and is greatly affected by factors such as environmental humidity. The curing speed may be even slower in an environment with low humidity.
  • Mechanical Properties: The mechanical strength is generally not as good as that of the addition-type, but it has good flexibility and can be suitable for some occasions where soft sealing or bonding is required.
  • Heat Resistance: The heat resistance is relatively slightly worse than that of the addition-type, and the long-term use temperature is generally around 150°C - 180°C.
  • Electrical Properties: The electrical insulation properties are good, but overall, it is slightly inferior to the addition-type.
  • Shrinkage Rate: The curing shrinkage rate is relatively large, which may have a certain impact on some high-precision bonding or sealing.
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