270 JOURNAL OF COSMETIC SCIENCE 0.014 ---------�- - � - · -·� - 0.012 :' 0.008 l J 0.006 0.004 o,._ __________________________________ ......,. 0 10 20 30 40 50 60 70 80 90 100 Water Content In Mlcroemulsion [%wt] Figure. 2. Influence of temperature on the viscosity of the microemulsion region of the SDS/pentanol/water system. Temperature 15°c 22°c 30°c 40°C Table II Temperature Influence on Viscosity of Water Data 1 (mN · s/m2) (mPa · s) 1.404 0.958 0.807 0.656 Data 2 (mN · s/m2 ) (mPa · s) 1.005* 0.801 0.656 * 20°C: data 1---(40) data 2---(41) data exp.-measured values. Data exp. (mN · s/m2) (mPa · s) 1.11 0.931 0.812 0.664 in various pharmaceutical and cosmetic formulations, where processing variables can result in a change of dispersed phase volume, size distribution, and particle-particle interaction as well as particle deformability, but also in studying the naturally occurring processes. Micelles can be considered as a simple model of the cell membranes present in the biological system (18,25,38,39). EXPERIMENT AL The sodium dodecyl sulphate, L-ascorbic acid, and 1-pentanol used were supplied by Fluka Chemie and RdH Laborchemicalien GmbH & Co. KG. Water was doubly redis tilled.
VITAMIN C AND SDS/PENTANOL/WATER SYSTEM 0.004 -----......------.......----- 55 0.0035 0.003 l 0.0025 b 0.002 "iii � 0.0015 0.001 0.0005 . - - - , - - - - -,- - - - - r - - - - r - - - - �iscoslty [Pax s] �shear rate (1/s] 50 45 ,!! 40 ;' 35 i 30 25 Cl) .c Cl) 0+-----.---.-----.,---....----.�-... 20 0.04 0.05 0.06 0.07 0.08 0.09 0.1 0.11 Shear Stress (Pa) 0.045 --------------------- 55 0.043 0.041 _ 0.039 = 0.037 e:. b 0.035 .§ 0.033 0.031 0.029 0.027 - - - - - , - - - - - � - - 50 45 40 � .! &! 35 i 30 25 Cl) .c Cl) 0.025 .... --.---.--.....--.... --...---+ 20 1.1 1.2 1.3 1.4 1.5 1.6 Shear Stress (Pa) 0.01 ----------------.------ 55 0.0095 - - - - - • - - - - - _, - - - 0.009 e 0.0085 ca i 0.008 'jg � 0.0075 0.007 0.0065 �cosily [Pax s] 50 45 ,!!! 40 � .! &! 35 1 30 .c Cl) � rate [1/s] 25 -- - - 1 - - - - - - , - - - - - - I - - - - - 0.006 +---.--....�--.--....--..---+ 20 0.15 0.2 0.25 0.3 0.35 0.4 0.45 Shear Stress (Pa) 271 Figure 3. Flow curves for (a) W /0 microemulsion, (b) biconrinuous system, and (c) O/W microemulsion.
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