Average Molecular Weight (Mn)

Kemulene 35: 33,000~37,000

Kemulene 45:  43,000~47,000

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Kemulene 50: 47,000~53,000

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Kemulene 55: 53,000~57,000

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Kemulene 60: 57,000~63,000

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Kemulene 65: 63,000~70,000

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Kemulene 75: 70,000~80,000

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Kemulene 85: 80,000~90,000

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Kemulene 95: 90,000~11,000

Features

  Kemulene medium molecular weight polyisobutylene (MMW PIB) typically has a number average molecular weight (Mn) ranging from approximately 30,000 to 15,000 g/mol. This molecular weight range gives it a unique set of properties and applications that fall between those of low and high molecular weight PIBs.

• Viscous Semi-Solid to Soft Solid: At room temperature, it generally appears as a transparent, colorless to light yellow, viscous semi-solid or a soft, pliable solid. The exact physical state depends on the specific molecular weight within the medium range.

• Good Tack and Adhesion: It exhibits a good balance of tack and cohesive strength, making it suitable for adhesives and sealants. It offers better cohesive strength than low molecular weight PIB.

• Moderate Viscosity: Compared to low molecular weight PIB, it has higher viscosity, providing better body and sealing properties. It has lower viscosity than high molecular weight PIB, making it easier to process in some applications.

• Excellent Flexibility and Elasticity: It offers good flexibility and elastic recovery over a wide temperature range due to its low glass transition temperature (Tg).

• Good Gas Impermeability: It provides good resistance to the permeation of gases and moisture, making it useful in sealing applications. It's generally better in this regard than low molecular weight PIB but not as high as very high molecular weight PIB.

• Good Chemical Resistance: It exhibits good resistance to water, acids, alkalis, and salts.

• Thermal and Oxidative Stability: It offers good resistance to degradation from heat and oxidation, contributing to long-term performance.

• Hydrophobicity: It is inherently hydrophobic, repelling water.

• Electrical Insulation Properties: It has good electrical insulation characteristics.

Applications

  Kemulene medium molecular weight PIB offers a valuable combination of adhesive, sealing, flexibility, and stability properties, making it a versatile polymer for a wide range of industrial and consumer applications.

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    Adhesives and Sealants:

• Pressure Sensitive Adhesives (PSA): Used as a base polymer or tackifier in tapes, labels, and protective films, offering a balance of tack and holding power.

• Sealants: Employed in construction sealants (e.g., insulating glass sealants, roofing membranes, weatherproofing), automotive sealants, and industrial sealants due to its flexibility, weather resistance, and gas impermeability.

• Caulking Compounds: Used as a primary binder in caulks and sealing compounds.

• Hot Melt Adhesives: A component in some hot melt adhesive formulations.

    ​Polymer Modification:

• Impact Modifier: Can be blended with other polymers (e.g., polyethylene) to improve flexibility, tear resistance, and impact strength, especially at low temperatures.

• Rubber Modification: Improves the flexibility, weather resistance, and adhesion of rubber in applications like tires and sealing parts.

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    Lubricants and Greases:

• Viscosity Modifier: Used to improve the viscosity index of lubricants.

• Thickener: Can act as a thickener in some grease formulations.

• Shield Grease: Used in shield greases for its protective and sealing properties.

    Construction Materials:

• Roofing Membranes and Coatings: Provides waterproofing, UV resistance, and weathering resistance.

• Insulating Glass Sealants: Acts as a primary seal due to its low gas and moisture permeability.

• Acoustic Barriers: Used in automotive and construction applications for sound damping.

    Automotive Applications:

• Sealants and Adhesives: For various automotive components.

• Damping Materials: Used for vibration and noise reduction.

• Fuel and Lubricant Additives: Can contribute to viscosity modification and other performance enhancements.

    Packaging:

• Adhesives: For sealing boxes and cartons.

• Protective Films: Enhances moisture and environmental damage resistance.