The sulfurization (vulcanization) of liquid silicone has a significant impact on its material properties, which is specifically reflected in the following aspects:
1. Changes in physical properties
Hardness changes:
The degree of sulfurization directly affects the hardness of liquid silicone. The higher the degree of vulcanization, the greater the hardness of the silicone, and vice versa. This characteristic allows liquid silicone to meet the hardness requirements of different application scenarios by adjusting the degree of sulfurization.
Elasticity and toughness:
Moderate sulfurization can improve the elasticity and toughness of silicone, giving it better rebound performance. However, excessive vulcanization will cause the material to become hard and brittle, reducing its impact resistance and service life.
Tensile and tear strength:
The degree of sulfurization has a significant impact on the tensile strength and tear strength of silicone. Reasonably sulfurized silicone has higher tensile strength and tear strength, while insufficient or excessive vulcanization will cause these properties to decrease.
2. Optimization of chemical properties
Improved chemical resistance:
After sulfurization, a cross-linked structure is formed between silicone molecules, making it more resistant to acids, alkalis and solvents, and suitable for a wider range of chemical environments.
Enhanced thermal stability:
The cross-linked structure improves the thermal stability of silicone, so that it can still maintain stable performance in high temperature environments and is suitable for high temperature working conditions.
Improved aging resistance:
Silicone after sulfurization has stronger resistance to thermal oxidation and UV resistance, which prolongs the service life of the material.
3. Influence of processing performance
Molding accuracy and dimensional stability:
The degree of sulfurization directly affects the molding accuracy and dimensional stability of silicone. Insufficient vulcanization may cause large shrinkage and dimensional deviation of the product, while excessive vulcanization may cause deformation or cracking.
Flowability and filling:
During the sulfurization process, the fluidity of silicone will gradually decrease. Reasonable control of the sulfurization time can ensure that the material has good fluidity and filling during molding, avoiding the generation of bubbles and defects.
4. Changes in appearance and touch
Transparency and color:
The degree of sulfurization has a significant effect on the transparency and color of silicone. Moderately sulfurized silicone maintains high transparency, while excessive vulcanization may cause yellowing or blackening.
Surface quality:
Poor sulfurization may cause cracks, cracks or burrs on the surface of silicone, affecting the appearance and feel of the product.
5. Weather resistance and service life
Improved weather resistance:
Silicone after sulfurization has stronger resistance to UV, ozone and moisture and heat aging, and is suitable for outdoor or harsh environments.
Extended service life:
By optimizing the sulfurization process, the service life of silicone products can be significantly improved, and the maintenance and replacement costs can be reduced.
6. Regulation of special properties
Anti-yellowing performance:
The degree of sulfurization has a direct impact on the anti-yellowing performance of silicone. Reasonably sulfurized silicone is not easy to turn yellow during long-term use, and maintains a beautiful appearance.
Breathing and water resistance:
Silicone after sulfurization still maintains excellent breathing and water resistance, and is suitable for application scenarios that require gas exchange or waterproof performance.
Summary
The sulfurization of liquid silicone is a key process link that determines its final performance. By precisely controlling the degree of sulfurization, the hardness, elasticity, chemical resistance, thermal stability and other properties of silicone can be optimized to meet the application needs of different fields. Insufficient or excessive sulfurization will lead to a decrease in material performance and affect the quality and service life of the product. Therefore, in actual production, appropriate sulfurization process parameters need to be selected according to specific needs.