I. Mechanism of Precipitated Silica's Influence on Silicone Rubber Transparency
Precipitated silica (fumed silica), as the main reinforcing filler in silicone rubber, has a significant impact on its transparency:

Particle Size and Dispersibility: Nanometer-sized precipitated silica (particle size 10-40nm), when uniformly dispersed, can effectively reduce light scattering and improve transparency. Imported precipitated silica, due to its narrow particle size distribution and fewer impurities, results in higher transparency in silicone rubber.

Surface Treatment Technology: Precipitated silica treated with silazane has good hydrophobicity and better compatibility with vinyl silicone oil, which can significantly improve the transparency of the product. Precipitated silica with a large specific surface area (145-300 m²/g) is more likely to yield high-transparency products than those with a smaller specific surface area. Process Parameter Control:

Kneading time of 2-3 hours ensures thorough mixing of fumed silica and vinyl silicone oil.
pH value must be controlled between 5.0 and 8.0; pH < 5.5 will cause significant yellowing of the silicone rubber.
Chloride ions and metal ion impurities can also cause yellowing; strict control of raw material purity is required.

II. Reinforcement Effect of Fumed Silica on the Mechanical Properties of Silicone Rubber
Mechanical Performance Improvement:

Tensile strength: Increased from <0.4 MPa for pure silicone rubber to over 16 MPa, an increase of 40 times.
Optimal addition amount: 40-50 parts (100 parts = 100 phr = 100g/100g raw rubber), tensile strength can reach 9.43 MPa when 50 parts are added.
Other properties: Significantly improved wear resistance, hardness, tear strength, and compression resistance.

III. Optimized Application Technology
Formula Optimization:
Using silane coupling agents to improve interfacial bonding.
Adding active agents such as diethylene glycol and glycerol to reduce the adsorption of fumed silica on accelerators.
Used in combination with vinyl silicone oil.
Process Control:

Mixing with a twin-screw extruder, controlling screw speed and temperature.
Combined treatment of UV curing and hot air aging.
Precision coating machine for self-adhesive layer coating.
Surface Modification Technology:
PDMS treatment (mechanical stirring method, solution dispersion method, surface modification method)
Silazane modification to improve hydrophobicity
Controlling crystal form, particle size, and dispersion

IV. Application Cases and Performance Comparison
Application Field | Performance Improvement | Technical Highlights
Transparent/Translucent Silicone Rubber | Transparency increased by 30% | Using imported high-purity fumed silica, silazane surface treatment
High-Temperature Vulcanized Silicone Rubber | Tensile strength reaches 16 MPa | Adding 50 parts of fumed silica, optimizing the kneading process
Self-Adhesive Tape Silicone Rubber | Adhesion strength increased by 45% | Twin-screw extrusion mixing, UV curing
Anti-Fatigue Silicone Rubber | Fast recovery in 1-2 seconds Jin Sanjiang's "Ultra-Strong Stretch, Whitening Resistance, and Rapid Recovery" Silica
Through the aforementioned technological optimization, the application of silica in silicone rubber has achieved a synergistic improvement in transparency and mechanical properties, providing crucial technical support for the development of high-end silicone rubber products. In the future, with the advancement of nanotechnology and surface modification technology, the performance of silica in silicone rubber will continue to be optimized.