Determination of Average Oxyethylene Chain Length of Nonionic Surfactants by Cloud Point Measurement

Studies on the soil redeposition of synthetic textile fibers (Part 7)

Abstract

The effect of the distribution of oxyethylene chain length of nonionic surfactants on the cloud point has been studied, using homogeneous C₁₂H₂₅O (CH₂CH₂O) _nH (n=08). The broader the distribution of oxyethylene chain length, the lower the cloud point becomes. A small deviation from Poisson distribution does not cause major difference in cloud point. The cloud point vs. oxyethylene chain length calibration curves for commercial p, t-C₈H₁₇C₆H₄O (CH₂CH₂O) _n-H, _i-C₉H₁₀C₆H₄O (CH₂CH₂O) _n-H and molecularly distilled C₁₂H₂₅ (CH₂CH₂O) n-H were obtained. The distribution of oxyethylene chain length of these samples is close to the Poisson distribution. Byproduced polyethylene glycol does not affect appreciably to the cloud point. This cloud point measurement is relatively rapid and accurate for determining the average oxyethylene chain length of nonionic surfactant. While, determination of the oxyethylene chain length by other methods requires elimination of polyethylene glycol, water, etc, and also forces not only to consume the time but alters the distribution of oxyethylene chain length in the process of the elimination, these are the disadvantages of other methods.