6533b836fe1ef96bd12a074a

RESEARCH PRODUCT

The use of utraviolet-visible spectrophotometry in the determination of average properties of nonylphenol ethylene oxide condensates

subject

description

Ultraviolet spectrophotometry is usd in the determination of average molecular weight (M), average degree of polymerization (X), the hydrophilic-lipophilic balance (HLB) and ethylene oxide percentage of nonylphenol ethylene oxide condensates. The method is based on determination of the absorptivity a, expressed in g lt-1 cm−1, from the absorbances measured at 275 nm for a series of dilutions of an aqeuous ethanolic solution (60:40, v/v/) of a given product, followed by numerical interpolation of this value in the expression a = f(HLB), log a = f(log M), and log a = f(log X). These expressions are obtained from reference samples or samples previously analyzed. The proposed method gives relative standard deviations of 1% for the estimation of m and X, and 0.5% for HLB and ethylene oxide percantage, with reasonable accuracy. .Aqueous solutions can be used but the method is then restricted to samples with HLB > 13. For the estimation of M, the molar absorptivity can be used, because the value obtained for this paramater (1700 remains constant for a variety of degrees of polymerization.