Polyethylene Glycol (PEG) H-(O-CH2-CH2)n-OH vs Propylene Glycol
Comprehensive comparison of Polyethylene Glycol (PEG) H-(O-CH2-CH2)n-OH and Propylene Glycol including physical properties, applications, safety considerations, and pricing. Alliance Chemical supplies both chemicals in various grades and concentrations.
Quick Comparison Summary
Polyethylene Glycol (PEG) H-(O-CH2-CH2)n-OH
- CAS:
- 25322-68-3
- Formula:
- H(OCH₂CH₂)ₙOH
Physical & Chemical Properties Comparison
| Property | Polyethylene Glycol (PEG) H-(O-CH2-CH2)n-OH | Propylene Glycol | Key Difference |
|---|---|---|---|
| Boiling Point | >200 °C (decomposes) | 188.2°C | Propylene Glycol boils 188.2°C higher |
| Flash Point ⚠️ | 182-287 °C (open cup) | 99°C | Propylene Glycol is more flammable |
| Density | 1.125 g/cm³ (20°C, PEG 400) | 1.036 g/cm³ | Propylene Glycol is denser |
| Water Solubility | Miscible with water | Miscible with water | Both fully water soluble |
| pH | 5.0 - 7.0 (50 g/L in H₂O, 20 °C) | 6.0-8.0 (50% aqueous solution) | Similar pH range |
| Molecular Weight | Varies | 76.09 g/mol | Propylene Glycol is heavier molecule |
| Melting Point | 4 - 60 °C (depending on molecular weight) | -59°C | Polyethylene Glycol (PEG) H-(O-CH2-CH2)n-OH melts 63°C higher |
| Vapor Pressure | <0.01 mmHg at 20°C (estimated for high molecular weight) | 0.13 mmHg at 20°C | Propylene Glycol is more volatile |
| Auto-ignition Temp ⚠️ | 360 - 420 °C (depending on molecular weight) | 371°C | Polyethylene Glycol (PEG) H-(O-CH2-CH2)n-OH auto-ignites at lower temp |
| Vapor Density | N/A | 2.62 (air = 1) | Data not available for direct comparison |
| Appearance | Clear, colorless liquid to white solid (depending on molecular weight) | Clear, colorless, viscous liquid | |
| Odor | Slightly sweet | Slightly sweet | Similar odor |
Data sourced from PubChem (NIH), OSHA Technical Guidelines, and Alliance Chemical laboratory analysis. Last verified June 2026.
Applications & Use Cases
Polyethylene Glycol (PEG) H-(O-CH2-CH2)n-OH Best For:
- Pharmaceutical excipient
- Cosmetic ingredient
- Plasticizer
- Lubricant
- Solvent
Propylene Glycol Best For:
- Industrial solvent
- Antifreeze
- Humectant
- Chemical intermediate
- Heat transfer fluid
Choosing Between Them
The right choice depends on your specific application, required purity, and handling capabilities. Contact our team for guidance on which chemical best fits your needs.
Safety & Handling Comparison
Storage Requirements
Always store in original containers in a cool, well-ventilated area per NFPA 30 guidelines. Refer to each product's SDS for specific storage temperature ranges and incompatible materials.
PPE Requirements
At minimum: chemical-resistant gloves, safety goggles, and adequate ventilation per OSHA 29 CFR 1910.132-138. Check each SDS below for chemical-specific PPE requirements.
Fire Hazard
Propylene Glycol has a lower flash point and requires extra fire precautions.
Safety Data Sheets (SDS)
Which Chemical Should You Choose?
Decision Snapshot
| Decision Factor | Better Fit | Why |
|---|---|---|
| Evaporation Profile | Polyethylene Glycol (PEG) H-(O-CH2-CH2)n-OH | Lower boiling point supports faster flash-off. |
| Fire Safety Margin | Polyethylene Glycol (PEG) H-(O-CH2-CH2)n-OH | Higher flash point generally reduces ignition risk in handling and storage. |
| Application Breadth | Propylene Glycol | Compares distinct listed use cases to avoid generic recommendations. |
| Purity Flexibility | Standard grades | Based on availability of 99%+ concentration options in current product metadata. |
Choose Polyethylene Glycol (PEG) H-(O-CH2-CH2)n-OH if:
- You specifically need support for pharmaceutical excipient applications.
- You specifically need support for cosmetic ingredient applications.
- You want a faster-evaporating solvent for quick-dry production steps.
- Fire-risk controls are a priority and you prefer the higher flash-point option.
Choose Propylene Glycol if:
- You specifically need support for industrial solvent applications.
- You specifically need support for antifreeze applications.
- You need a higher-boiling solvent that stays in-process longer.
- You can manage stricter flammable-liquid controls for lower flash-point performance.
Commercial & Fulfillment Snapshot
Built for purchasing teams that need predictable dispatch, compliant documentation, and freight flexibility from parcel to full truckload.
| Procurement Advantage | Polyethylene Glycol (PEG) H-(O-CH2-CH2)n-OH | Propylene Glycol |
|---|---|---|
| Grade & Concentration Coverage | multiple concentration options by application with industrial/lab procurement support. | 50% to 30% with industrial/lab procurement support. |
| Packaging Depth | small packs through bulk freight quantities for parcel, pallet, and truckload planning. | small packs through bulk freight quantities for parcel, pallet, and truckload planning. |
| Dispatch SLA | Lane-scheduling cutoff is 1 PM CT (Mon-Thu) and noon CT Friday. Outbound dispatch from Taylor, TX typically completes within 1-2 business days. | Lane-scheduling cutoff is 1 PM CT (Mon-Thu) and noon CT Friday. Outbound dispatch from Taylor, TX typically completes within 1-2 business days. |
| Freight Optionality | UPS Ground for small packs plus LTL/FTL lanes through ABF, SEFL, Saia, XPO, and partner carriers. | UPS Ground for small packs plus LTL/FTL lanes through ABF, SEFL, Saia, XPO, and partner carriers. |
| Compliance Readiness | SDS ready now; COA/TDS support available pre-PO and post-order. | SDS ready now; COA/TDS support available pre-PO and post-order. |
| Bulk Procurement CTA | Request bulk quote or call (512) 365-6838. | Request bulk quote or call (512) 365-6838. |
Need Help Deciding? Our technical team can help you choose the right chemical for your specific application. Email sales@alliancechemical.com for expert guidance.
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Alliance Chemical supplies both Polyethylene Glycol (PEG) H-(O-CH2-CH2)n-OH and Propylene Glycol in various grades and package sizes.