Viscosities and Surface Tension of N, N' Methylureas in Aqueous Solutions Measured with Survismeter, a Novel Instrument
Viscosities (η, ± 0.06 × 10-5 N s m-2), surface tension (γ ± 0.05 × 10-3 N m-1) and densities (ρ ± 1 × 10-2 kg m-3) for 0.005 to 0.25 mol kg-1 1-methylurea (MU), 1, 3-dimethylurea (DMU) and 1, 1, 3, 3-tetramethylurea (TMU) as N, N' methylureas at interval of 0.005 mol kg-1 were measured at pH 7.99 to 7.01 and 293.15, 298.15 and 303.15 K temperatures. Intrinsic viscosities [η] and limiting surface tension γ0 are obtained from regression with molality, m. Contributions of -CH3 (methyl) groups are derived from differences in [η] and γ0 values individually between their subsequent ureas. The [η] and γ0 values infer weakening of hydrophilic interactions with -CH3 and strengthening of hydrophobic, and TMU shows structure making effect. As compared to measurements of viscosities and surface tension individually with viscometer and stalagmometer, the Survismeter minimizes 2/3rd of materials, human efforts and infrastructure with better accuracies. It prevents evaporation of liquids during surface tension measurements.
Survismeter, Surface Tension, Viscosity, Intrinsic Viscosities, Tetramethylurea, Structure Breaking/Making Interactions.
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