Polyisobutylene (PIB, CAS 9003-27-4) is a saturated linear polymer produced by the cationic polymerization of isobutylene. Due to its stable chemical structure, PIB is widely used across lubricant additives, adhesives, sealants, and butyl-related applications.
Physical Properties of Polyisobutylene (PIB)
Appearance: Colorless, odorless, non-toxic viscous liquid or semi-solid
- Density: ~0.92 g/mL at 25 °C
- Melting point: Typically 54–56 °C
- Boiling point: Approximately 300 °C
- Molecular formula: Repeating unit C₄H₈
- Structural unit: –(CH₂–C(CH₃)₂)–
Molecular weight ranges:
- Low MW PIB: ~350–3,500
- Medium MW PIB: ~10,000–100,000
- High MW PIB: ~100,000–1,000,000 (solid at high MW)
Molecular weight strongly influences the viscosity, physical form, and application performance of polyisobutylene (PIB).
Chemical and Environmental Stability
- Thermal resistance: Maintains stable performance at elevated temperatures
- Chemical resistance: Excellent resistance to acids, alkalis, salts, water, ozone, and aging
- Weather resistance: Resistant to oxidation and UV exposure, suitable for outdoor use
- Electrical insulation: High volume resistivity, free of harmful dielectric substances
- Gas barrier properties: Outstanding air tightness, ideal for sealing materials and butyl-based systems
Safety and Storage
- Health effects: May cause mild irritation to skin and mucous membranes; high vapor concentrations may lead to suffocation or toxic symptoms
- Fire and explosion risk: Flammable; keep away from strong oxidizing agents
- Storage conditions: Store in a cool, dry, well-ventilated area; avoid heat and direct sunlight
Applications of Polyisobutylene (PIB)
The properties of polyisobutylene (PIB) are closely related to its molecular weight, enabling broad industrial use in:
- Lubricant and fuel additives
- Adhesives and sealants
- Chewing gum base
- Pharmaceutical and cosmetic formulations
- Butyl rubber modification and sealing systems