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Evaluation of the rheological properties of sulfonic acids and sodium sulfonates
Author(s) -
Berna J. L.,
Bengoechea C.,
Moreno A.,
Rounds R. S.
Publication year - 2000
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1007/s11743-000-0139-7
Subject(s) - chemistry , sulfonate , sulfonic acid , linear alkylbenzene , sodium , rheology , dodecylbenzene , organic chemistry , chemical engineering , pulmonary surfactant , materials science , composite material , biochemistry , engineering
Sulfonic acids of linear alkylbenzene (LAB) are converted into the corresponding sodium salts to produce the most widely used anionic surfactant worldwide, linear alkylbenzene sulfonate (LAS). Used in many industrial applications and consumer products, the physical and mechanical properties of the sulfonates are strongly dependent on the LAB manufacturing process. Until recently, commercial alkylation of benzene has employed aluminum chloride or hydrogen fluoride catalysts, but a new fixed‐bed alkylation process (DETAL) has been developed with improved 2‐phenyl isomer selectivity and low tetralin concentration. In order to better understand the rheology of LAS in aqueous media, a comprehensive comparative evaluation of sulfonic acids and sodium sulfonates of the three LAB process derivatives has been done using dynamic mechanical rheometry, steady shear viscometry, and X‐ray diffraction for phase identification. LAB sulfonic acids are Newtonian fluids in the temperature range of 20–60°C. The neat AlCl 3 , HF, and DETAL sulfonic acids are Newtonian fluids within the temperature range of 20–60°C. At 30 wt%, all three sulfonates are Newtonian at 20–60°C, and the 40 wt% AlCl 3 sodium sulfonate remains in the Newtonian regime within this temperature range. Lamellar liquid crystalline phases have been identified for the sulfonates in the concentration range of 40–60 wt% in water at 20–60°C, and a hexagonal lattice phase also has been identified for DETAL sodium alkylbenzene sulfonate at 40 wt%, 60°C. The presence of anisotropic phases results in non‐Newtonian pseudoplastic behavior with time‐dependent viscosity functions.