High Cis Elastomeric Polyisobutylene HMW from Mexico
High molecular weight (HMW) elastomeric polyisobutylene with high cis content, over 95% isobutylene by weight, imported as primary polymer under HTS 3902.20.10.00. Ideal for sealants, roofing membranes, and vibration dampeners due to superior elasticity. Primary form ensures classification before vulcanization.
Duty Rate — Mexico → United States
10%
Rate breakdown
9903.05.5510%Except for products described in headings 9903.05.85–9903.05.92 and 9903.05.94, articles the product of Mexico, as provided for in U.S. note 52 to this subchapter
Import Tips
• Conduct FTIR spectroscopy for customs verification of structure
• Differentiate from butyl rubber copolymers to stay in 3902
• Beware of moisture absorption affecting elasticity claims