High Cis Elastomeric Polyisobutylene HMW

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.

Import Duty Rates by Country of Origin

Origin CountryMFN RateCh.99 SurchargesTotal Effective Rate
🇨🇳ChinaFree+35.0%35%
🇲🇽MexicoFree+10.0%10%
🇨🇦CanadaFree+10.0%10%
🇩🇪GermanyFree+10.0%10%
🇯🇵JapanFree+10.0%10%

Alternative Classifications

This product could be classified differently depending on its characteristics or intended use.

3907.99Lower: 16.5% vs 35%

If chemically modified with halogens

Halogenated derivatives like chlorobutyl are classified under 3907 per subheading note (a)(3) 'Other'.

3920.43.50Higher: 39.2% vs 35%

If containing plasticizers over 50% by weight

Plasticized polymers meeting US note criteria shift to plates/sheets in 3920.43.

3504.00Lower: 14% vs 35%

If peptizers or processing aids added

Rubber processing chemicals are in Chapter 35, not primary polymers.

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Import Tips & Compliance

Conduct FTIR spectroscopy for customs verification of structure

Differentiate from butyl rubber copolymers to stay in 3902

Beware of moisture absorption affecting elasticity claims