Interactions between cationic starch and mixed anionic surfactants
نویسندگان
چکیده
The interactions of cationic starch (CS, degree of substitution=0.8)/mixed anionic surfactant/water systems were investigated. The surfactants investigated were sodium dodecyl sulphate (SDS), sodium octanoate (NaOct), sodium decanoate (NaDe), sodium dodecanoate (NaDod), sodium oleate (NaOl ) and sodium erucate (NaEr). The concentration of CS varied from 0.001 to 10 wt.%. The effect of mixing on the micellisation of the binary surfactant solutions can be described to a good approximation by taking into account only the effects of the volume difference between the hydrocarbon chains. Mixed micelle formation on CS depends on the chain-length difference in quite the same way as for free mixed micelles. Aggregation of the mixed micelles of the surfactants and the polymer coils produces a gel-like complex phase. The water content of the gel phase in equilibrium with aqueous solution increases when the chain-length difference between the two surfactants increases. The more surface-active component is strongly enriched in the polymer complexes and gels. © 1999 Elsevier Science B.V. All rights reserved.
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