ISSN:
1435-1536
Keywords:
Microemulsions
;
non-ionic surfactants
;
phase behaviour
;
structure
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract The non-ionic surfactant pentaethylenglycol-4-octylphenyl ether (igepal CA-520) represents a good industrial alternative to the long-tail members of the CiEj family. In this paper, the phase behaviour of the microemulsion system igepal CA-520/n-decane/brine is studied in detail. An isotropic phase was found, as well as liquid crystalline and cream-like structures, depending on composition and temperature. Such structures can either form single-phase homogeneous mixtures, or coexist with other structures when phase separation takes place. Below surfactant concentration of about 20%, more complicated phase equilibria develop as temperature changes. The presence of different additives shifts the temperature ranges where the different phases exist, while keeping the general shape of the phase diagram, which agrees with the general rules for non-ionic surfactants. Complementary rheology experiments reveal a change from non-Newtonian to Newtonian behaviour during the phase transition from a lamellar phase to the isotropic microemulsion. A structure of water droplets associated in clusters can be proposed from SANS and electrical conductivity.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00665640
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