HS code · 6-digit subheading
HS Code 3903.90 – Styrene polymers; in primary forms, n.e.c. in heading no. 3903
HS code 3903.90 is the 6-digit subheading for styrene polymers, in primary forms, n.e.c. in heading no. 3903. It is used for styrene-butadiene-styrene (SBS) block copolymers, styrene-isoprene-styrene (SIS) block copolymers, styrene-ethylene/butylene-styrene (SEBS) block copolymers, styrene-maleic anhydride (SMA) copolymers and styrene-butadiene rubber (SBR) in primary forms.
What HS 3903.90 covers
This 'not elsewhere specified' category for styrene polymers in primary forms covers a diverse range of specialized styrene-based polymers that don't fit into the more specific categories like expansible PS, general PS, SAN, or ABS. These often include block copolymers, graft copolymers, or blends designed for unique performance characteristics, such as thermoplastic elastomers. Exporters are typically specialized chemical companies, and importers are manufacturers requiring advanced materials for niche applications in sectors such as adhesives, sealants, footwear, asphalt modification, and specialized films. Key aspects involve the high-value nature of these materials, the complexity of their chemical structures, and the need for precise formulation to meet specific performance criteria for demanding end-uses.
- Covers
- Styrene-butadiene-styrene (SBS) block copolymers
- Styrene-isoprene-styrene (SIS) block copolymers
- Styrene-ethylene/butylene-styrene (SEBS) block copolymers
- Styrene-maleic anhydride (SMA) copolymers
- Styrene-butadiene rubber (SBR) in primary forms
- Styrene-acrylic copolymers
- Styrene-butadiene latex (SBL) in primary forms
- Examples
- Kraton Polymers (SBS, SIS, SEBS)
- Sartomer (Styrene-Acrylic)
- Polyscope (SMA)
- Asahi Kasei (SBR)
- Dynasol (SBS)
Codes often confused with 3903.90
Common mistake. Can be confused with 390319 (other polystyrene) if the complex copolymer structure is overlooked, or with 4002 (synthetic rubber) if the primary form of SBR is mistaken for a finished rubber product.
Top exporters and importers of HS code 390390, 2025
In 2025, the largest exporter of HS code 390390 in UN Comtrade data was South Korea, with 18% of world exports; the largest importer in UN Comtrade data was China, with 18% of world imports. Countries that did not report 2025 data are estimated from partner records, which can understate them.
Top exporters 2025 · share of world exports
- 1 South Korea $663M 18% of world exports
- 2 United States $619M 17% of world exports
- 3 Germany $330M 9.0% of world exports
World total: $3.7B Reported figures on UN Comtrade ↗
Top importers 2025 · share of world imports
- 1 China $747M 18% of world imports
- 2 Mexico $293M 7.2% of world imports
- 3 Germany $277M 6.8% of world imports
World total: $4.1B Reported figures on UN Comtrade ↗
How these figures are built
109 countries reported 2025 trade to UN Comtrade in HS 2022, and their own totals are used. Countries that did not report are estimated from what other countries recorded trading with them. Those estimates miss trade with other non-reporting countries, so they can be low, and a non-reporting country can rank higher than shown or be missing from the list. World totals add both and leave out trade between two non-reporting countries. Figures are in current US dollars; reported imports are mostly valued CIF and exports FOB, and exports include re-exports. The UN Comtrade links show the underlying records; they can also list a few reporters left out here (regional groups and older HS editions).
Source: UN Comtrade (United Nations Statistics Division), 2025 annual data.
Brazil NCM codes for 3903.90 3
Brazil splits HS 3903.90 into 3 NCM codes, Mercosur's 8-digit tariff lines.
- 3903.90.10 Methyl methacrylate-butadiene-styrene copolymersCopolímeros de metacrilato de metilbutadieno-estireno (MBS)
- 3903.90.20 Acrylonitrile-styrene-butyl acrylate copolymersCopolímeros de acrilonitrilo-estireno-acrilato de butilo (ASA)
- 3903.90.90 Other styrene polymers in primary formsOutros
All Brazil NCM codes in heading 39.03 →
Source: Siscomex NCM table, updated Oct 2026. The Portuguese text is official; the English is our translation.
Questions about HS 3903.90
What is HS code 390390?
HS code 390390 is a 6-digit subheading in the Harmonized System that covers: Styrene polymers; in primary forms, n.e.c. in heading no. 3903. This 'not elsewhere specified' category for styrene polymers in primary forms covers a diverse range of specialized styrene-based polymers that don't fit into the more specific categories like expansible PS, general PS, SAN, or ABS. These often include block copolymers, graft copolymers, or blends designed for unique performance characteristics, such as thermoplastic elastomers. Exporters are typically specialized chemical companies, and importers are manufacturers requiring advanced materials for niche applications in sectors such as adhesives, sealants, footwear, asphalt modification, and specialized films. Key aspects involve the high-value nature of these materials, the complexity of their chemical structures, and the need for precise formulation to meet specific performance criteria for demanding end-uses.
What products fall under HS code 390390?
Styrene-butadiene-styrene (SBS) block copolymers, styrene-isoprene-styrene (SIS) block copolymers, styrene-ethylene/butylene-styrene (SEBS) block copolymers, styrene-maleic anhydride (SMA) copolymers, styrene-butadiene rubber (SBR) in primary forms, styrene-acrylic copolymers, styrene-butadiene latex (SBL) in primary forms
What are common misclassifications for HS code 390390?
Can be confused with 390319 (other polystyrene) if the complex copolymer structure is overlooked, or with 4002 (synthetic rubber) if the primary form of SBR is mistaken for a finished rubber product.
Which countries are the top exporters of goods under HS code 390390?
In 2025, the top exporters of HS code 390390 in UN Comtrade data were South Korea ($663M, 18% of world exports), the United States ($619M) and Germany ($330M). World exports came to about $3.7B, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Countries that did not report 2025 data are estimated from partner records, which can understate them.
Which countries are the top importers of goods under HS code 390390?
In 2025, the top importers of HS code 390390 in UN Comtrade data were China ($747M, 18% of world imports), Mexico ($293M) and Germany ($277M). World imports came to about $4.1B, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Countries that did not report 2025 data are estimated from partner records, which can understate them.
How is HS code 390390 structured?
HS code 390390 is a 6-digit subheading under the Harmonized System. The first 2 digits (39) identify the chapter, digits 3-4 (03) identify the heading, and digits 5-6 (90) specify the subheading. This code is standardized globally by the World Customs Organization.
What is the Brazil NCM code for HS code 390390?
Brazil splits HS code 390390 into 3 NCM codes: 3903.90.10 (Methyl methacrylate-butadiene-styrene copolymers), 3903.90.20 (Acrylonitrile-styrene-butyl acrylate copolymers), 3903.90.90 (Other styrene polymers in primary forms). The first 6 digits of each match the HS code.