The transparency of liquid silicone is related to hardness. Generally speaking, liquid silicone with higher hardness has relatively lower transparency, and liquid silicone with lower hardness is easier to achieve high transparency. The following is a specific analysis:
Principle level
The hardness of liquid silicone is mainly determined by its molecular chain structure, cross-linking density, and the type and content of additives. Usually, the molecular chains of liquid silicone with higher hardness have a higher degree of cross-linking and are arranged more tightly. This structure will cause more scattering and reflection of light when passing through, thereby reducing transparency. The molecular chains of liquid silicone with lower hardness are relatively loose, with lower cross-linking density, so light can pass through more smoothly, so the transparency is often higher.
Practical application performance
Low hardness liquid silicone: The hardness is usually below 10 Shore A, and the transparency is high, which can reach more than 90% (measured in visible light transmittance). It is often used to make products that require high transparency, such as contact lenses, optical lens filling materials, transparent hoses, etc.
Medium hardness liquid silicone: The hardness range is roughly between 10-50 Shore A, and the transparency will decrease, generally between 70%-90%. It is often used to make products that require both certain strength and transparency, such as mobile phone cases, transparent buttons, sealing gaskets, etc.
High hardness liquid silicone: The hardness is usually above 50 Shore A, and the transparency is further reduced, which may be only 50% - 70%. High hardness liquid silicone is mainly used to make products with high strength and wear resistance requirements, such as mechanical parts, tool handles, automotive parts, etc., in which transparency is usually not the primary consideration.