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.

Property Scientific Common
Autoignition Temperature 229°C @ 1013.25 hPa 444°F @ 760mm Hg
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 138°C @ 1013.25 hPa 280°F @ 760 mm Hg
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 244.9°C @ 1013.25 hPa 473°F @ 760 mm Hg
Δ BP/δ P (750 to 770 mm Hg) 0.052°C/mm Hg
Normal Freezing Point -6.5°C 20.3°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 25°C 0.008 hPa 0.006 mm Hg
Dynamic Viscosity at 20°C 35.7 mPa s 35.7 cP