9902.10.67 - Poly(2-methylpropene) (polyisobutylene), other than elastomeric (CAS No. 9003-27-4) (provided for in subheading 3902.20.50)

HTS 9902.10.67 specifically classifies non-elastomeric poly(2-methylpropene), also known as polyisobutylene. This material is a synthetic polymer with distinct physical and chemical properties that differentiate it from other polymers. Its primary characteristic is its non-elastic nature, which is a key criterion for its classification under this specific provision.

This category is part of Chapter 99, which encompasses temporary legislation and special provisions. Unlike the primary commodity chapters (01xx through 98xx) that classify goods based on their inherent nature and function, Chapter 99 codes are dynamic and can be subject to change based on trade agreements, import restrictions, or other legislative actions. Therefore, the classification here is not solely based on the material's composition but also on its status within specific trade regulations.

Since HTS 9902.10.67 is a leaf node, it does not have further subcategories. This means that any import of non-elastomeric poly(2-methylpropene) that falls under this temporary or special provision will be classified directly under this code. It is important to note that the description explicitly states "provided for in subheading 3902.20.50," indicating that this Chapter 99 code is a modification or restriction applied to goods that would otherwise be classified under the permanent structure of the HTS, specifically under heading 3902 for polymers of ethylene, but in this case, it is polyisobutylene.