Poly(ethyl vinyl ether) (PVE, CAS 25104-37-4) is a synthetic polymer base oil produced from the cationic polymerization of ethyl vinyl ether. It is used as a base stock for compressor oils, refrigeration oils, vacuum pump oils and specialty lubricants, offering a useful balance of viscosity-temperature behaviour, low pour point and additive compatibility – with viscosity grades customizable to the application.
1. What Is Poly(ethyl vinyl ether)?
PVE is a homo-polymer of ethyl vinyl ether (CH2=CH-O-C2H5) with a linear polyether backbone. Because the molecular weight (and therefore kinematic viscosity) is controlled during polymerization, the product can be tuned from low-viscosity fluids (ISO VG 10-32) to higher-viscosity base oils (VG 46, 68, 100), matching the requirements of different lubricant systems.
2. Chemistry and Key Properties
| Property | Typical behaviour |
|---|---|
| Structure | Linear poly(ethyl vinyl ether), ether backbone with ethyl side chains |
| Kinematic viscosity (40 °C) | Customisable (VG 32/46/68 standard) |
| Appearance | Colorless to light yellow transparent liquid |
| Density (15 °C) | 0.980-1.000 g/cm3 |
| Acid value | ≤0.03 mg KOH/g (low, clean base) |
| Saybolt color | ≥15 (light, high purity) |
| Pour point | Low (good low-temperature behaviour) |
The polyether backbone gives excellent hydrolytic stability and low deposit formation compared with some ester base stocks, while the ethyl side chain keeps the fluid mobile at low temperature.
3. Production Technology
PVE is made by cationic polymerization of ethyl vinyl ether:
- Feedstock: ethyl vinyl ether monomer, high purity, dry.
- Polymerization: cationic initiation (e.g. boron trifluoride etherate or other Lewis acid systems) in a solvent at controlled low temperature; monomer is fed to control molecular weight and distribution.
- Quenching and finishing: termination, solvent stripping, filtration and viscosity adjustment to the target grade.
Molecular weight control is the key process variable – it directly sets the kinematic viscosity at 40 °C, which is why viscosity grades can be customised.
4. Product Grades and Specifications
| Grade | Kinematic viscosity 40 °C (mm2/s) | Typical use |
|---|---|---|
| PVE 32 | ~32 | Light hydraulic/refrigeration oils |
| PVE 46 | ~46 | Compressor/refrigeration oils |
| PVE 68 | 65-71 | Compressor, vacuum pump and specialty lubricants |
Full specification for PVE 68: appearance colorless to light yellow transparent liquid; kinematic viscosity 65-71 mm2/s; residual solvent ≤0.01; water ≤0.05 wt%; density (15 °C) 0.980-1.000 g/cm3; acid value ≤0.03 mg KOH/g; Saybolt color ≥15; dimer (GC) <0.1%.
5. Applications Overview
- Refrigeration and compressor oils – good refrigerant compatibility and low-temperature fluidity.
- Vacuum pump oils – low vapor pressure and clean residue.
- Hydraulic and gear oils – viscosity-temperature stability as base stock.
- Specialty lubricants and additive carriers – carrier for soluble and dispersion-type additives.
6. Application Details
6.1 Refrigeration and compressor service
For refrigeration and air-conditioning compressors, the oil must remain fluid at evaporator temperature and mix adequately with the refrigerant. PVE’s low pour point and controlled viscosity help maintain lubrication over the operating range; grade selection (VG 32/46/68) follows compressor type and charge.
6.2 Vacuum pumps
Low volatility and clean, low-deposit behaviour make PVE suitable for mechanical vacuum pump service where mineral oils may degrade or leave residues.
6.3 Hydraulic fluids
As a base stock in hydraulic formulations, PVE contributes shear stability and a flat viscosity-temperature curve, though full formulation requires antiwear, antioxidant and antifoam packages.
7. PVE vs Other Synthetic Base Oils
| Base oil | Strength | Consideration |
|---|---|---|
| PVE (poly alkyl vinyl ether) | Custom viscosity, low pour point, clean, refrigerant compatible | Specialty position; fewer global suppliers |
| PAO | Excellent all-round, widely available | Higher cost at low temperature extremes |
| PAG (polyalkylene glycol) | Good for R134a/CO2 systems, water soluble grades | Hygroscopic; additive selection critical |
| Esters | High VI, biodegradable options | Hydrolysis sensitivity, seal interaction |
PVE occupies a niche where clean, low-pour, refrigerant-compatible base oil with tailored viscosity is needed – often in refrigeration/compressor and specialty vacuum service.
8. Buying Guide and Custom Viscosity
- Specify the target kinematic viscosity at 40 °C (ISO VG 32/46/68 or custom).
- Request COA with viscosity, density, acid value, water, Saybolt color and dimer content per batch.
- Confirm packaging (200 kg drum / IBC) and storage life.
- For custom grades, state the viscosity target and application; viscosity is controlled at polymerization.
9. Safety and Handling
- Flammable liquid – keep away from ignition sources; use proper grounding when transferring.
- Avoid prolonged skin contact; use gloves and eye protection.
- Store sealed in cool, ventilated area; dispose per local regulations.
10. FAQ
Can you supply PVE at viscosities other than 32/46/68?
Yes – viscosity is customisable at the polymerization step; contact us with your target grade.
Is PVE suitable as a refrigeration oil?
PVE is used in refrigeration and compressor applications where refrigerant compatibility and low-temperature fluidity matter; select the grade for your compressor and charge.
11. References and Further Reading
- PubChem entry for poly(ethyl vinyl ether) (CID via PubChem REST API).
- Supplier COA and MSDS for the specific grade quoted.
- Industry literature on synthetic base oils and viscosity classification (ISO 3448).
This article is published for industrial and technical reference by PolyblueChem. Verify all values against the supplier’s COA and applicable standards before specification.
PolyblueChem supplies poly(ethyl vinyl ether) (PVE, CAS 25104-37-4) in custom viscosity grades with COA and MSDS. Contact us for specifications and quotations.