Standard International Trade Classification
U.S. imports of Polyisobutylene, Primary Forms (SITC 57512) totaled $11.6M in August 2026, imported from 18 countries.
Importers of Polyisobutylene, Primary Forms paid $1.9M in duties in August 2026, an average duty rate of 16.59% — duty actually collected as a share of the imports that cleared customs, not the published tariff schedule. Polyisobutylene, Primary Forms imports of $11.6M in August 2026 ran 38% above the year-to-date monthly average of $8.4M.
Last updated: August 2026 dataPolyisobutylene (PIB) in primary forms is a specialty synthetic rubber-like polymer valued for its exceptional gas impermeability, tackiness, and chemical resistance, making it a critical input for inner tubes, sealants, adhesives, lubricant additives, and pharmaceutical closures. Molecular weight is the defining commercial variable: low-molecular-weight PIB is used in adhesives and lubricant viscosity modifiers, while high-molecular-weight grades serve tire and industrial sealing applications. Because PIB is a relatively concentrated specialty market with fewer global producers than commodity polyolefins, supply chain disruptions can have outsized pricing effects. Importers should confirm whether the grade being sourced is a pure PIB homopolymer or a butyl rubber precursor, as the latter may fall under a different classification.
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233 import shipments a month
Pure polyisobutylene is a homopolymer of isobutylene, while butyl rubber (IIR) is a copolymer of isobutylene with a small percentage of isoprene that introduces vulcanizable unsaturation. The two are classified differently — butyl rubber falls under synthetic rubber headings — so a certificate of composition confirming the absence of isoprene comonomer is important documentation for PIB imports.
Commercial PIB spans a wide range: low-molecular-weight grades (roughly 300–5,000 Mn) are viscous liquids used in adhesives and fuel additives, medium grades are semi-solid, and high-molecular-weight grades (above 100,000 Mn) are solid or highly viscous and used in sealants and tire applications. The molecular weight specification should be clearly stated on the commercial invoice and technical data sheet to support classification and end-use verification.
Basic heading 240 of 465 in section 5
Basic heading 57512 · $11.6M of $27.5B
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Imports · August 2026
origin
Germany and France together supply 41% of it. Brazil pays 44.0% duty; France 10.0%.
customs district
Census does not publish district detail for this classification system.
destination
Census does not publish state detail for this classification system.
entry
Census does not publish port detail for this classification system.
ImportsExports
Imports
$11.6MYoY · free account
Exports
$12.9MYoY · free account
12-mo low · imports
Low · free accountOver the twelve months to August 2026, the U.S. imported $92.2M of Polyisobutylene, Primary Forms and exported $125.2M.
Through August 2026. Source: U.S. Census Bureau.