Polyimide Prepolymer Powder from Mexico
Thermosetting polyimide prepolymer powder in primary form for aerospace composites. Under 3911.90.91.50 as NES thermosetting product, classified by predominant imide monomer units.
Duty Rate — Mexico → United States
16.5%
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
• Include cure cycle instructions proving thermoset transformation from prepolymer state
• Test for 95% imide content to rule out copolymer shifts per subheading note (a)(2)
• Comply with ITAR if for defense applications; separate from tariff classification