Sourcing polyisobutylene from China

6% duty, with qualifying grades at 0%

Read from the UK Trade Tariff on 6 November 2026, heading 3902 covers polymers of propylene or other olefins in primary forms. This guide covers polyisobutylene only. The polypropylene granules guide explains the wider heading.

Both PIB lines have a standard China duty of 6%, with no anti-dumping or countervailing measure recorded. Liquid hydrogenated polyisobutene under 3902 20 00 20 has a 0% suspension. Under 3902 20 00 90, the suspension covers PIB with number-average molecular weight from 700 to 800. These suspensions exclude mixtures, preparations and products made up of different components containing the listed products.

The tariff attaches import waste control to both lines. Waste shipment controls apply only where the material is waste. For Chinese material sold as recovered or off-specification stock, confirm its status and the applicable requirement with your customs broker before shipping. Confirm the commodity code using the composition, physical form and grade datasheet.

Specify PIB viscosity and molecular weight

State whether you need hydrogenated liquid PIB or another PIB grade, and name the intended use, such as a sealant, adhesive or lubricant formulation. Specify viscosity with its test temperature and method, molecular-weight range, colour, volatile content and any additives. Compare the proposed grade with your approved material using the same test conditions.

Agree packaging, storage instructions, batch traceability and the certificate of analysis before ordering. Confirm with HSE the UK REACH registration position for the polymer, monomers and additives, including any exemption or upstream coverage. Ask the supplier for its registration position and safety data sheet rather than assuming blanket clearance.

Worked duty example

Illustrative example, not a quote: Illustrative order: 20 tonnes of other polyisobutylene outside the suspension under 3902 20 00 90, invoiced at £18,000 free on board, with £1,500 of freight and insurance to the UK. The customs value is £19,500. Duty at 6% is £1,170. Import VAT at 20% is charged on the customs value plus duty, £20,670, so it is £4,134. Import taxes total £5,304; a VAT-registered importer can usually reclaim the VAT, so the lasting cost is the £1,170 of duty. The import duty and VAT guide explains each step.

Inspection checklist

Identity: match the product name, hydrogenation status and declared composition to the approved grade and batch certificate.

Viscosity: test arrival samples at the agreed temperature using the agreed method, and compare results with the specification.

Appearance: check colour, visible contamination and consistency against a retained approved sample.

Packing: check seals, leaks, container condition and batch labels, and retain a sample from each lot. Agree sampling through the quality inspection guide.

What goes wrong

A nominally equivalent PIB can behave differently when viscosity was measured at another temperature or the molecular-weight distribution differs. Added diluent can change formulation behaviour and invalidate assumptions about a suspension. Test the proposed grade in your own formulation before approving bulk supply.

Leaking containers and missing batch records make arrival checks harder. Hold material with unexplained colour, contamination or viscosity differences until the supplier resolves the discrepancy against the agreed specification.

Cambridge China Bridge sources these products for UK businesses, checking the factory and the documents before shipment. See factory verification. For repeat volumes, see container programmes.