3902.90.00.10 - Polybutylene

This HTS category, 3902.90.00.10, specifically classifies Polybutylene. Polybutylene is a type of polymer derived from butene-1, which is a specific olefin. It is typically supplied in primary forms, such as granules, powders, or blocks, intended for further processing into various articles. Its primary application is often in the manufacturing of pipes, films, and adhesives due to its flexibility and chemical resistance.

Within the broader heading of "Polymers of propylene or of other olefins, in primary forms," this subcategory distinguishes itself by focusing solely on polybutylene. While there is a sibling category also listed as "Other" (3902.90.00.50), the specific designation "Polybutylene" for 3902.90.00.10 indicates a more precise classification for this particular polymer. Therefore, when classifying polymers of other olefins (excluding propylene), the key is to identify whether the material is specifically polybutylene.

As this classification represents a leaf node in the HTS structure, there are no further subcategories. Classification at this level requires the accurate identification of the polymer as polybutylene, based on its chemical composition and origin from butene-1. The determination between this specific category and any other "other" olefin polymers rests on confirming the presence and predominance of polybutylene as the material.