Studies on viscosity build-up properties of sodium alcohol ether sulphates

Narrow and broad range distributed ethoxylates of linear C-12-C-14 alcohols were synthesised using a calcium-based unconventional catalyst and NaOH, r espectively. Their composition was determined by gas chromatography. Sulpha tes were synthesised in the traditional way by reaction of ethoxylates with sulphur trioxide in a film reactor and neutralised with sodium hydroxide. Products were characterized by the ethoxylate homologue distributions and a cid value of the intermediate sulphuric acid derivatives. Viscosity build-u p properties of the narrow and broad range distributed ethoxylates-based so dium alcohol ether sulphates were studied. Effects of ethoxylate homologue distribution were compared with those of average ethoxylation grade and sul phation degree. It was shown that the acid number of the obtained sulphates , ethoxylate homologue distribution, average polyaddition degree and sodium chloride content influenced remarkably the thickening ability of ethoxylat es. Furthermore, it was found that the limited content of the longer ethoxy late chains in narrow range distributed alcohol ethoxylates is responsible for enhanced viscosity build-up properties of their sodium sulphate derivat ives. The following empirical relationship was obtained: log eta = (2.99 +/- 1.25) + (3.78 +/- 0.86) x 10(-2) V - (1.48 +/- 0.15)N-a v - (2.69 +/- 0.7) x 10(-2) A(N) + (0303 +/- 0.058) x C-surf + (0.832 +/- 0.041) x C-NaCl where eta is the viscosity in cP, V is the distribution coefficient, N-av i s the average oxyethylation degree, A(N) is the acid number of alcohol ethe r sulphuric acid and C-surf and C-NaCl are concentrations (wt%) of the stud ied surfactants and sodium chloride, respectively. (C) 1999 Society of Chem ical Industry.