TCS Industries Limited (China-sourced API supplier) supplies Styrene-Isoprene-Styrene (SIS) Rubber – Thermoplastic Elastomer for Adhesives CAS 25038-32-8 for pharmaceutical B2B procurement — COA, MSDS, and technical documentation available on request.
> Overview
| Product Name | Styrene-Isoprene-Styrene (SIS) Rubber – Thermoplastic Elastomer for Adhesives |
|---|---|
| Structural Formula |  |
| CAS Number | 25038-32-8 |
| Molecular Formula | (C8H8)m(C5H8)n (styrene-isoprene block copolymer) |
| Molecular Weight | Grade-dependent (typ. 100,000–300,000 g/mol) |
| InChIKey | Not applicable (block copolymer) |
| SMILES | Available on request where applicable |
| Appearance | White to pale yellow crumb or pellets |
| Purity / Grade | By agreed specification and batch COA |
| Storage | Keep tightly closed in a cool, dry, well-ventilated place |
Styrene-Isoprene-Styrene (SIS) rubber (CAS 25038-32-8) is a thermoplastic elastomer (TPE) with a triblock copolymer structure: polystyrene end blocks provide physical crosslinks, and the polyisoprene midblock provides elastomeric behavior. SIS combines the processability of thermoplastics with the elasticity of vulcanized rubber. It is used in hot-melt pressure-sensitive adhesives (HMPSA), sealants, and modified bitumen for roofing membranes.
TCS Industries Limited, a Hong Kong-based trading and sourcing company, supplies SIS rubber in various molecular weight grades for adhesive, sealant, and polymer modification programs.
> Applications
Hot-melt pressure-sensitive adhesives (HMPSA)
SIS is the base polymer for hot-melt PSA formulations used in labels, tapes, hygiene products (diapers, feminine care), and medical adhesives. It is compounded with tackifying resins (C5, C9, rosin esters), plasticizing oils, and antioxidants to achieve target peel, tack, and shear properties. The unsaturated isoprene midblock provides high tack but requires antioxidant stabilization. Kim et al. (J Appl Polym Sci, 2006, 99:2132–2139) characterized the structure-property relationships of SIS-based hot-melt pressure-sensitive adhesives and the effect of tackifier type on peel and shear performance.
Bitumen modification and sealant applications
SIS is used to modify bitumen for polymer-modified asphalt (PMA) in roofing membranes and road paving. The polystyrene domains form a physical network that improves high-temperature softening point, low-temperature flexibility, and elastic recovery of bitumen. SIS is preferred over SBS (styrene-butadiene-styrene) in applications requiring higher tack and better compatibility with aliphatic tackifiers.
> Sourcing & Supply
TCS Industries Limited supports development, qualification and commercial purchasing discussions for Styrene-Isoprene-Styrene (SIS) Rubber – Thermoplastic Elastomer for Adhesives with buyers in South America, Europe, the United Kingdom, Australia, New Zealand, Mexico and Canada.
- Evaluation and commercial quantities: 25 kg samples for adhesive formulation trials; pallet quantities (900–1125 kg) for production. Multiple grades with different molecular weights and styrene content available.
- Pallet quantities and production campaigns: repeat supply is coordinated against packaging, lead time, annual demand and destination-market import requirements.
> Quality & Documentation
Key specification parameters include styrene content (typically 14–22%), solution viscosity (Brookfield, 25% in toluene), melt flow rate, volatile matter, ash, diblock content, molecular weight distribution, and colour (Gardner). Different grades are characterized by molecular weight, styrene/isoprene ratio, and linear vs. radial architecture. COA and MSDS are standard.
> Packaging
SIS rubber is supplied as white to pale yellow crumb or pellet in 25 kg kraft paper bags or PE-lined bags, palletized and shrink-wrapped. Store at controlled room temperature (below 30 °C) protected from direct sunlight and UV exposure to prevent oxidative degradation of the isoprene midblock. Shelf life is typically 12 months from production. Labels and documents are checked before dispatch.
> Pricing & MOQ
Pricing is quoted by specification, packaging and destination. Common commercial discussions use 25 kg bag/drum formats, pallet quantities and production-campaign planning; smaller samples may be reviewed for qualified formulation teams.
> Regulatory & Compounding Context
SIS rubber is not classified as dangerous goods for transport. Not a hazardous substance under REACH (polymer exemption applies, but component monomers are registered). FDA-compliant grades (21 CFR 175.105, 175.125) are available for indirect food contact adhesive applications. Buyers should specify food-contact compliance requirements at inquiry.
> Alias Index
- Chemical name: Poly(styrene-block-isoprene-block-styrene)
- CAS Number: 25038-32-8
- Polymer class: Thermoplastic elastomer (TPE), Styrenic block copolymer (SBC)
- Related polymers: SBS (styrene-butadiene-styrene, CAS 9003-55-8), SEBS (hydrogenated SBS)
- Common names: SIS rubber, SIS block copolymer, Styrene-isoprene-styrene
- Commercial request terms: SIS rubber adhesive grade, styrene-isoprene block copolymer, HMPSA base polymer, SIS for bitumen modification, TCS Industries Limited
> FAQ
What is the difference between SIS and SBS?
SIS (styrene-isoprene-styrene) has an isoprene midblock. SBS (styrene-butadiene-styrene) has a butadiene midblock. SIS provides higher tack, better compatibility with aliphatic tackifiers, and more open time. SBS has better UV resistance. Both are unsaturated and require antioxidant protection.
What documents are available for Styrene-Isoprene-Styrene (SIS) Rubber – Thermoplastic Elastomer for Adhesives orders?
COA and MSDS are standard for commercial discussions. COO, packing list, invoice and other import-support documents can be arranged according to order scope.
Can TCS Industries Limited support Styrene-Isoprene-Styrene (SIS) Rubber – Thermoplastic Elastomer for Adhesives supply to South America?
Yes. We support B2B buyers in Argentina, Colombia, Chile, Peru, Ecuador, Uruguay, Bolivia, Brazil, Paraguay, Venezuela, Guyana and Suriname, subject to route and document review.
Do you support Europe, the United Kingdom, Australia, New Zealand, Mexico and Canada?
Yes. These destinations can be reviewed for project supply, import documents, packaging and logistics planning before quotation.
Is SIS food-contact compliant?
FDA-compliant SIS grades are available for indirect food-contact adhesive applications per 21 CFR 175.105 and 175.125. Specify food-contact requirement at inquiry. Not all grades meet FDA compliance — confirm the specific regulation and food-contact condition at inquiry.
What tackifiers are used with SIS?
SIS is formulated with C5 aliphatic petroleum resins, hydrogenated C5 resins, rosin esters, and polyterpene resins. Tackifier selection affects tack, peel adhesion, shear strength, and aging stability. C5 resins are preferred for SIS compatibility. C9 aromatic resins are more compatible with the styrene end blocks.
Can you arrange samples before commercial purchasing?
Samples or evaluation quantities may be reviewed for qualified buyers after target specification, application and destination-market requirements are clarified.
How is Styrene-Isoprene-Styrene (SIS) Rubber – Thermoplastic Elastomer for Adhesives packaged for export?
Packaging is confirmed by quantity and material properties. Typical options include foil bags, HDPE containers, fibre drums, 25 kg bags or palletized export packaging.
Can buyer-defined specifications be reviewed?
Yes. Send the specification, methods, impurity limits and required documents. TCS can review feasibility before confirming quotation and lead time.
What payment terms are normally used?
Standard payment is 100% T/T before dispatch unless a different arrangement has been approved for an established commercial account.
What lead time should buyers expect?
Lead time depends on stock, batch size, document scope and destination. Available stock can move faster; made-to-order or pallet programs require longer planning.
Why does SIS require antioxidant protection?
The isoprene midblock contains unsaturated C=C bonds susceptible to oxidative degradation (chain scission and crosslinking). Antioxidants (hindered phenols, phosphites) are added during compounding and processing to prevent viscosity changes, colour development, and adhesive performance loss. Storage should be in cool, dark conditions.
Last reviewed: June 2026
Evaluation and research orders (≤10 kg) are shipped with COA, MSDS, and certificate of origin. Bulk commercial orders (>10 kg) qualify for volume pricing with a full technical documentation package available on request.
> Request a Quote
If your team already has a target application, estimated quantity, destination market, or documentation requirements, send those details so the commercial response can be prepared more efficiently.