Definly Chemicals supplies 3-Mercaptopropionic Acid (3-MPA, CAS 107-96-0) — the dominant chain transfer agent used in polycarboxylate ether (PCE) superplasticizer polymerization for molecular weight control. Our 98%+ purity 3-MPA ships in HDPE drums and IBC totes, with full ADR/IMDG-compliant dangerous goods documentation for sea and overland freight worldwide.
Thank you for reading this post, don't forget to subscribe!Quick Facts
| Chemical Name | 3-Mercaptopropionic Acid |
| Synonyms | 3-MPA, Mercaptopropionic Acid, β-Mercaptopropionic Acid |
| CAS Number | 107-96-0 |
| Molecular Formula | C₃H₆O₂S |
| Molecular Weight | 106.14 g/mol |
| Purity | ≥ 98% (99% available) |
| Appearance | Colorless to pale yellow liquid with strong thiol odor |
| Water Content | ≤ 0.5% |
| Packaging | 200 kg HDPE drums, 1,000 kg IBC totes |
| UN/Class | UN 3265, Class 8, Packing Group II |
| Sample MOQ | 1 MT |
| FCL MOQ | 20 MT |
| FOB Port | Qingdao |
Primary Application: PCE Chain Transfer Agent
3-MPA is added during PCE polymerization to control the molecular weight of the resulting polymer. The thiol group (-SH) reacts with growing polymer radicals, terminating chain propagation and starting new chains. By adjusting 3-MPA dosage, PCE manufacturers can target specific molecular weight distributions for different applications.
- Low dosage (0.5–1.0%) — produces higher molecular weight PCE with better slump retention. Suited for ready-mix and long-haul concrete delivery.
- Mid dosage (1.0–1.5%) — balanced PCE for general-purpose ready-mix and standard precast.
- High dosage (1.5–2.5%) — produces lower molecular weight PCE with faster cement dispersion. Suited for high-early-strength precast and specialty admixtures.
3-MPA dosage interacts with macromonomer chemistry. Use less 3-MPA with HPEG (which is more reactive); use standard dosage with TPEG and EPEG. See our PCE Macromonomer page for macromonomer specifications and our TPEG vs HPEG vs EPEG comparison article for full recipe implications.
Other Industrial Applications
- Mercapto-acid coupling chemistry — building block for thiol-ene click reactions and specialty polymer functionalization
- Metal corrosion inhibitor synthesis — intermediate for industrial corrosion inhibitor formulations
- Polymer modification — thiol-functional polymer building block
- Pharmaceutical and specialty chemical synthesis — intermediate in custom synthesis
Handling, Storage, and Safety
3-MPA has a strong thiol odor (similar to other low molecular weight thiols). It is corrosive (skin contact and inhalation) and requires standard chemical PPE: gloves, safety glasses, and ventilation. Store in cool, dry, well-ventilated area below 30°C, away from oxidizers, strong bases, and incompatible materials. Sealed shelf life is 12 months from manufacture date.
Maintain 3-MPA in dedicated storage segregated from food, low-odor goods, and finished PCE inventory to avoid odor cross-contamination. PCE plant operators typically dose 3-MPA from sealed feed lines into the polymerization reactor, minimizing operator exposure.
Sourcing & Logistics
Definly ships 3-MPA in 200 kg HDPE drums (palletized) or 1,000 kg IBC totes. Sea freight requires IMDG-compliant packaging and dangerous goods declaration; we issue all required paperwork (ADR/IMDG declaration, emergency response codes, MSDS in target market language). FOB Qingdao pricing typically applies; CIF available on request.
For PCE compounders running steady polymerization volumes, 3-MPA is commonly consolidated into mixed-FCL shipments alongside macromonomer, 2-HEA, and acrylic acid — reducing per-unit logistics cost and simplifying customs paperwork. See our market pages for region-specific lead times.
Documentation Provided
Each shipment includes Commercial Invoice, Packing List, Bill of Lading, Mill Test Certificate / Certificate of Analysis per batch, MSDS in target market language, Certificate of Origin (Form E for ASEAN, GSP Form A where applicable), and Dangerous Goods Declaration with UN 3265 / Class 8 / PG II designation. Third-party SGS test reports available on request. See our Certifications & Compliance page for full details.
Frequently Asked Questions
What is 3-mercaptopropionic acid used for?
3-MPA is the dominant chain transfer agent in PCE superplasticizer polymerization. Its thiol group caps growing polymer chains, controlling the molecular weight distribution of the final PCE. It is also used in mercapto-acid coupling chemistry, polymer modification, and metal corrosion inhibitor synthesis.
What dosage of 3-MPA is typical in PCE polymerization?
Typical 3-MPA dosage is 0.5-2.5% by weight of total monomer charge. Lower dosage (0.5-1.0%) produces higher molecular weight PCE with better slump retention; higher dosage (1.5-2.5%) gives lower molecular weight PCE with faster cement dispersion. Optimal dosage depends on macromonomer chemistry, target Mn, and application.
What purity should I specify for 3-MPA?
For PCE polymerization, 98%+ purity is standard. Critical impurities to monitor: free thiol content, water content (<0.5%), and dipropionic disulfide. Higher-purity grades (99%+) are available for specialty applications but rarely needed for standard PCE production.
How is 3-MPA shipped and stored?
3-MPA ships in HDPE drums (200 kg) or IBC totes (1,000 kg). Store in cool, dry, well-ventilated area below 30 deg-C, away from oxidizers and strong bases. Sealed shelf life is 12 months. The thiol odor is strong; store in dedicated storage area away from food and other low-odor materials.
Is 3-MPA classified as dangerous goods for shipping?
3-MPA falls under UN 3265 (corrosive liquid, acidic, organic, n.o.s.), Class 8, Packing Group II. Sea freight requires IMDG-compliant packaging and dangerous goods declaration. Definly issues all required paperwork including ADR/IMDG documentation, MSDS in target market language, and emergency response codes.
Request a Quote
Email [email protected] or WhatsApp +86 186 6370 6930 with your purity grade (98% or 99%), volume, and destination port. We respond within 24 business hours. For complex orders involving 3-MPA plus other PCE inputs in one consolidated FCL, we typically deliver a detailed proposal within 2–3 business days. Use our contact form for written inquiries.
Related on This Site
Related Products
- PCE Macromonomer (TPEG / HPEG / EPEG)
- 2-Hydroxyethyl Acrylate (2-HEA)
- Acrylic Acid (AA)
- PCE Superplasticizer