1. Molecular weight and distribution
Number average molecular weight: The number average molecular weight of medium molecular weight polyisobutylene is generally between 20,000 and 45,000.
Molecular weight distribution width index: This index reflects the degree of dispersion of molecular weight. Narrowly distributed polyisobutylene has more stable and uniform performance.
2. Physical properties
Appearance: Usually a colorless to light yellow viscous liquid or semi-solid.
Density: Generally around 0.92g/mL.
Flash point: A higher flash point means better safety. The flash point varies depending on the product model. For example, the flash point of the PB1300 model is 220°C, and the flash point of the PB2400 model is 240℃.
3. Chemical properties
Volatile mass fraction: The lower the volatile content, the higher the product quality. Generally, the volatile content is required to be ≤1.0%.
Antioxidant content: Some products will specify the content of antioxidants or whether to add antioxidants to ensure the stability of the product during use.
4. Impurity content
Water content: Too high water content will affect the performance and stability of the product. Generally, the water content is required to be ≤70mg/kg.
Ash content: Ash mainly comes from impurities in the production process, and its content should be controlled at a low level.
5. Performance indicators
Viscosity-temperature performance: When used as a lubricant additive, it is necessary to have good viscosity-temperature performance to ensure the viscosity stability of the lubricant at different temperatures.
Adhesion performance: When used in adhesives, rubber products and other fields, adhesion performance is an important quality indicator, which directly affects the bonding effect and performance of the product.
Stability: Including thermal stability, oxidation stability, etc., to ensure that the product has stable performance under different use environments and conditions.