160 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Illill p. H. S. '::O MINERAL OIL lall SWEET ALMOND OIL I• MIGLYOL 812 5o =, . .,,, Figure 1. Relationship between the occlusivity of emulsions and HLB values of the surfactants (Montane 80©/Montanox 80©). The general formula of emulsions is water/oil/surfactant: 80/15/5. Significance of the difference between the emulsions at various HLB for each oil: **p 0.01 P.H.S. Perhydrosqualen RESULTS OCCLUSIVITY OF OILS As shown on Table I, there is no direct relationship between occlusivity and polarity of the four oils studied. The dielectric constant which is related to polarity was the same for P.H.S. and mineral oil, whereas the occlusivity of these oils were 78 _+ 5 and roll p.H.S. MINERAL OIL SWEET ALMOND OIL MIGLYOL 812 50 25 Figure 2. As figure 1 replace Montane 80©/Montanox 80 © by Simulsol 92©/Simulsol 96 ©. Significance of the difference: *p 0.05, **p 0.01 *Fatty acid triglycerid (C8-C•2) **Seppic-Montanoir, Paris, france.

OCCLUSIVITY OF AQUEOUS EMULSIONS 161 35 + 4 respectively. For Miglyol 812 ©, the dielectric constant was 3.78 the occlusivity being 57 _+ 3. RELATION BETWEEN OCCLUSIVITY OF EMULSIONS AND HLB VALUES The occlusivity of emulsions having an oil/surfactant ratio equal to three was measured for various HLB. The results obtained from emulsions stabilized with ester surfactants (Fig. 1) and those stabilized with ether's one (Fig. 2) showed that for each oil, there was an HLB value for which the occlusivity of the emulsions was maximal whatever the surfactant used. As an example the occlusivity was maximum for an emulsion containing P.H.S. and ester surfactants to HLB = 9.25 (Oc%: 61 + 2). It was of interest to note that for the P.H.S. two O/W emulsions at HLB = 9.25 (Oc% -- 61 ___ 2) and HLB = 8.5 (Oc% = 47 ___ 5) were significantly more occlusive than a W/O emulsion at HLB = 4.3 (Oc% = 39 + 3). OCCLUSIVITY AND OIL/SURFACTANT RATIO Emulsions with the greatest occlusivity were chosen, the range of HLB was between 8.5 and 11.5, and the surfactants used were only the Montane-Montanox 80 © mixtures. As shown in Fig. 3, whatever the nature of the oil, occlusivity was higher when the I-Ip. H.S. /lB [] MINERAL OIL / /-t • •1" / I SWEET ALMOND ,LYOL,2 50 25 ** * - 8,5 9,25 10,5 11,75 Figure 3. Relationship between the occlusivity of emulsions and the proportion of oil and surfactants (Montane 80©-Montanox 80 ©) they contain at various HLB's 1: water/oil/surfactant: 80/10/10 2: water/oil/surfactant: 85/10/5 3: water/oil/surfactant: 80/15/5 Significance of the difference between the emulsions for each oil with various oil-surfactant ratio: *p 0.05 **p • 0.01 *Fatty acids triglycerid **Seppic-Montanoir, Paris, France.