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About Silicone Fluids
The Difference between "Straight" and "Modified" Silicone Fluids
The Unique Properties of Silicone
  • Low-Temperature Resistance

    Low-Temperature Resistance

    Silicone fluid has excellent low-temperature resistance. DM-FLUID remains fluid even at -50°C. Methylphenyl silicone fluid was specially developed for low-temperature applications, so it remains fluid even in environments of -65°C. Since temperature has little effect on viscosity, these products are ideal for applications in cold regions.

  • Thermal Conductivity

    The thermal conductivity of dimethyl silicone fluid is lower than that of common organic compounds (nearly the same as that of benzene and toluene) and is roughly 25% that of water. Although thermal conductivity increases with higher viscosities, it becomes nearly constant at viscosities above 100 mm2/s. The thermal conductivity of DM-FLUID is 2.4-3.5x10-4 cal/cm·sec·°C at viscosities below 20 mm2/s, and roughly 3.7-3.8x10-4 cal/cm·sec·°C at viscosities over 50 mm2/s.

  • Specific Heat

    The specific heat of silicone fluid varies somewhat depending on viscosity, but is generally about one-third that of water. The values are comparable to common organic compounds that have low specific heat. The specific heat of DM-FLUID is 0.39-0.47 cal/g·°C for viscosities below 20 mm2/s, and approximately 0.36 cal/g·°C at viscosities over 100 mm2/s.

  • Chemical Stability

    Silicone fluid is nearly chemically inert and is virtually unaffected by 10% alkaline aqueous solutions or 30% acid aqueous solutions at ambient temperatures. However, viscosity increases and gelation can occur if even trace amounts of acids or alkalis are introduced at high temperatures. Silicone fluid is almost unaffected by the presence of aluminum, stainless steel, and most other metals. However, lead, selenium, and tellurium can cause gelation. Precautions must therefore be taken during handling.

    Chart Effects of DM-FLUID-50cs on metals
      Effects of DM-FLUID-100cs on solder

  • Corrosivity and Effects on Other Materials

    Corrosivity and Effects on Other Materials

    Silicone fluid has no adverse effect on metals, nor on most other substances. However, it may reduce the volume and weight of some rubber and plastic compounds due to extraction of the plasticizers when subjected to high temperatures. This tendency is especially strong for low-viscosity fluids. Particular care must be exercised when silicone fluid comes into contact with rubber sealing materials.

    Chart Effects of DM-FLUID-100cs on various plastics
      Effects of DM-FLUID-100cs on various rubbers
  • Surface Tension

    Surface Tension

    The surface tension of silicone fluid is much lower than that of water or common synthetic oils. Silicone fluids spread easily over the surfaces of various substances, and are thus widely used as release agents, defoamers, and ingredients for cosmetics.

    Liquid Surface tension (mN/m)
    Mineral oil
    16 to 21

  • Releasability and Nonadhesiveness

    Releasability and Nonadhesiveness

    The application of silicone fluid to mold surfaces prevents the adhesion of other materials, thereby enhancing mold releasability. Silicone fluids are widely used as release agents because they have excellent heat resistance and do not contaminate molds or molded materials.

  • Defoaming properties

    Defoaming properties

    Added in small amounts, silicone fluid has excellent defoaming action. Silicone fluid is primarily used as a defoamer for oil-based foaming fluids.

  • Water Repellency

    Water Repellency

    Silicone fluid also has excellent water repellency. The degree of water repellency can be represented by water contact angle, which is over 90° for DM-FLUID. An excellent and durable water-repellent coating can be obtained by applying F-9W-9 or DM-FLUID to glass, ceramic, or fiber using a bake-on process. Silicone fluid can also be used to improve the fluidity of powders and prevent coagulation.

    Chart Water contact angle
    Illust Water repellency mechanism of DM-FLUID
  • Physiological Effects

    Generally speaking, silicone fluid is physiologically inert and poses almost no risk to people or animals. Low-viscosity products excepted, DM-FLUID is nearly harmless unless ingested in large quantities. It is thus widely used as an ingredient in cosmetics and pharmaceuticals.

    Chart Results of various safety tests

  • Resistance to Shear Stress

    Silicone fluid has extremely high shear resistance, and it resists shear degradation at high speeds and high loads, meaning it has a long operating life. When synthetic or mineral oils pass through narrow gaps under pressure, shear stress destroys the oil molecules, causing a drop in viscosity. In contrast, with dimethyl silicone fluid of viscosities below 1,000 mm2/s, there is almost no change in viscosity. However, with high-viscosity products there may be an apparent drop in viscosity depending on the shear velocity. Note that this is not due to destruction of the molecules, so the viscosity returns to the initial level when the shear stress is removed. The shear resistance of silicone fluids is over 20 times greater than that of even top-quality petroleum-based oils.

    GraphDM-FLUID: apparent kinetic viscosity and shear velocity

  • Radiation Resistance

    In terms of radiation resistance, methylphenyl silicone fluid is superior to dimethyl silicone fluid, and the stability of radiation resistance increases proportionately with the amount of phenyl groups present in the molecules. Due to this property and its resistance to high and low temperatures, methylphenyl silicone fluid is widely used in the high-temperature parts of radiological equipment.

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