Physical Properties
Diethylene glycol is similar to ethylene glycol in many respects but has a higher boiling point, viscosity and specific gravity – as might be predicted from its higher molecular weight. Its properties are sufficiently different from those of ethylene glycol to make it a more desirable material in many applications.
Physical Properties of Diethylene Glycol
| Scientific | Common | |
|---|---|---|
| Autoignition Temperature | 364°C | 687°F |
| Critical Pressure | 4,605 kPa | 34,540.3 mm Hg |
| Critical Specific Volume | 0.312 L/gmol | 5.00 ft3/lbmol |
| Critical Temperature | 406.85°C | 764.33°F |
| Dielectric Constant | 31.69 | 31.69 |
| Electrical Conductivity at 20°C | 0.42 x 10-6 mhos/cm | 0.0042 micromhos/cm |
| Evaporation Rate (Butyl Acetate = 1) | <0.001 | <0.001 |
| Flammable Limits in Air, Upper | 12.3%(V) | 12.3%(V) |
| Flammable Limits in Air, Lower | 2.0%(V) | 2.0%(V) |
| Flash Point, Closed Cup (Pensky-Marten Closed Cup ASTM D93) |
154°C | 310°F |
| Flash Point, Open Cup (Cleveland Open Cup ASTM D92) |
163°C | 325°F |
| Heat of Combustion at 25°C | -2,154.82 kJ/gmol | -8,730.4 Btu/lb |
| Heat of Vaporization at 1 atm | 57.9 kJ/gmol | 234.4 Btu/lb |
| Molecular Weight | 106.12 g/mol | 106.12 g/mol |
| Normal Boiling Point | 245.3°C | 473.5°F |
| Δ BP/δ P (750 to 770 mm Hg) | 0.052°C/mm Hg | |
| Normal Freezing Point | -9.0°C | 15.8°F |
| Onset of Initial Decomposition | 240°C | 464°F |
| Refractive Index, nD, at 20°C | 1.4472 | 1.4472 |
| Solubility in Water at 20°C | 100.0 wt% | 100.0 wt% |
| Solubility of Water in DEG at 20°C | 100.0 wt% | 100.0 wt% |
| Specific Gravity (20/20°C) | 1.1182 | 1.1182 |
| δ Specific Gravity/δ T(10 to 40°C) | 0.00073/°C | 0.00073/°C |
| Surface Tension at 25°C | 44.8 mN/m | 44.8 dynes/cm |
| Vapor Density (air = 1) | 3.65 | 3.65 |
| Vapor Pressure at 20°C | 0.0003 kPa | 0.002 mm Hg |
| Viscosity at 20°C | 35.7 mPs | 35.7 cP |