3902.20.50.00 - Other

This HTS category, 3902.20.50.00, specifically encompasses "Other" polyisobutylene, meaning it covers polyisobutylene that does not fall under the "Elastomeric" classification (3902.20.10.00). Polyisobutylene itself is a synthetic polymer derived from the polymerization of isobutylene. These materials are characterized by their high molecular weight and are often used for their impermeability to gases, chemical resistance, and tackiness.

The key differentiator for this subcategory is the absence of elastomeric properties as the primary defining characteristic. While polyisobutylene can exhibit some flexibility, this classification is intended for forms of polyisobutylene that are not specifically designed or manufactured for rubber-like elasticity. This could include various forms such as resins, pellets, or powders that are not primarily intended for applications where stretching and recovery are paramount.

Given that this is a leaf node, there are no further subcategories branching from this specific HTS code. Therefore, classification within 3902.20.50.00 relies on identifying the material as polyisobutylene and confirming that it does not meet the criteria for elastomeric polyisobutylene. End-use applications not focused on elasticity, such as components in adhesives, sealants, or as modifiers in other plastic formulations, would typically fall under this residual category.