In the field of materials science, fumed white carbon black (silicon dioxide), as a high-performance inorganic nanomaterial, is widely utilized in industries such as rubber, coatings, and electronic encapsulation due to its high specific surface area and excellent reinforcing properties. However, the hydrophilicity imparted by the abundant hydroxyl groups on its surface results in poor compatibility with organic matrices (e.g., rubber raw胶, here referring to unvulcanized rubber), thereby limiting the full expression of the material's comprehensive performance. The application of hexamethyldisilazane (also known as tetramethyldisilazane or TMDS) has opened up a new avenue for the surface modification of white carbon black.

From a chemical perspective, the reactive silicon-nitrogen bonds in the TMDS molecule undergo a condensation reaction with the hydroxyl groups on the surface of white carbon black. The silicon atom in TMDS bonds with the oxygen atom of the hydroxyl group, releasing a molecule of ammonia or silanol, and forming a methyl-terminated siloxane layer on the white carbon black surface. This process not only eliminates the hydrophilic hydroxyl groups but also introduces hydrophobic methyl groups, fundamentally altering the surface properties of white carbon black. For instance, untreated white carbon black tends to aggregate rapidly in water, whereas after TMDS treatment, its dispersibility in organic solvents improves significantly.

In actual processing techniques, fumed white carbon black is typically dispersed in an inert solvent such as toluene, followed by the addition of an appropriate amount of TMDS. The mixture is then stirred and reacted at a certain temperature for several hours. Parameters such as reaction temperature, time, and TMDS concentration are crucial to the modification effect. Research has shown that when the reaction temperature is controlled within the range of 80 - 100°C and the mass ratio of TMDS to white carbon black is 3% - 5%, the modified white carbon black exhibits the best hydrophobicity, with the contact angle increasing from an initial value of less than 30° to over 110°.

The advantages of TMDS-treated white carbon black are particularly prominent in the rubber industry. Its interfacial compatibility with rubber raw胶 is greatly improved, leading to more uniform dispersion. This effectively enhances the tensile strength, tear strength, and abrasion resistance of rubber products. When this technology is applied in tire production, it can reduce tire rolling resistance by 15% - 20% while simultaneously improving wet grip, achieving a dual enhancement in energy-saving and safety performance.

Despite the immense potential demonstrated by this technology, it still faces challenges. The relatively high cost of TMDS and the need for proper treatment of the ammonia gas generated during the reaction process to meet environmental protection requirements are issues that need to be addressed. In the future, researchers will focus on developing efficient catalysts and optimizing processes to reduce costs, thereby promoting the widespread application of this technology in more fields.

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High termperature curing polysilazane, pls check IOTA 9108, IOTA 9118.