260 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table II Isotropic Oily Phase Formation Capacity of the Binary Mixture P.H.S.-Surfactant: Viscosity and Conductivity of Emulsions and Their Non-volatile Parts [Perhydrosqualene-ester surfactant (HLB 8.5 and 11.5)-sodium lactate (NaL)] % of Sodium Lactate in Emulsions Parameters HLB 0 2.5 5 Water % of water or aqueous solution of NaL incorporated into P. H.S.-surfactant 8.5 5.5 1: l mixture 11.5 0 10% aqu. 20% aqu. sol sol. of NaL of NaL 4.8 4.3 0 0 Viscosity of non-volatile parts of emulsions 8.5 180 447 298 (mPa.s.) 11.5 699 40l 195 Conductivity of emulsions and their 8.5 ( Emulsions 5.4 X 10 -3 3. l 4 non-volatile parts Non-volatile parts 0 8 X 10 -5 7 X 10 ¸ (mS) Emulsions 11. X 10 -2 9.6 16.6 11.5 Non-volatile parts 3.2 X 10 -3 6 X 10 -2 4.6 X 10 -3 that made with HLB 11.5 surfactant (699 mPa. s). Addition of NaL increased viscosity in the HLB 8.5 surfactant emulsion and decreased it in the HLB 11.5 emulsion. Conductivities of emulsions and their non-volatile parts. The conductivities of emulsions made with HLB 8.5 surfactant were less than those made with 11.5 surfactant (Table II). Conductivity rose in all cases in the presence of NaL. The conductivities of non-volatile parts were always much lower than those of corre- sponding emulsions. P.H.S.-ESTER OR ETHER SURFACTANT-UREA (H.L.B. 9.25) Influence of humectant on the occlusivities of emulsions and their non-volatile parts. Figure 2 indicates that the occlusivities of emulsions prepared from P.H.S. with either ester or ether surfactants having an HLB of 9.25 did not noticeably change in the presence of urea. The emulsions prepared with ester were more occlusive (about 52%) than those prepared with ether type (about 21%). The non-volatile parts manifest the same oc- clusive characters as did their corresponding emulsions. Isotropic oily phase formation capacities of PHS surfactant mixtures. Isotropic oily phase formation capacities of mixtures prepared from P.H.S. with ester or ether surfactants having an HLB of 9.25 were similar and did not seem to noticeably change in the presence of urea (Table III). Viscosities of non-volatile parts of emulsions. The viscosity of the non-volatile part of the emulsion prepared with ester surfactant (205 mPa. s) was lower than that (334 mPa.s) of the non-volatile part prepared with ether surfactant (Table III). introduction of urea increased viscosity in both cases.

EFFECTS OF HUMECTANTS ON EMULSION OCCLUSIVITY 261 801 SURFACTANT ' ESTER ETHER o EMULSIONS ß NON VOLATILE PARTS [] EMULSIONS ß NON VOLATILE PARTS 70 60- 50- 40- 30- 20 _:3- 10- , , , , , 0 0.62 1.25 2.5 3.75 5 URE % Figure 2. Influence of urea on the occlusivities of emulsions prepared from perhydrosqualene with ester or ether surfactants of HLB 9.25. % humectant values shown for non-volatile parts are concentrations of humectants in emulsions before volatiles are removed. Conductivities of emulsions and their non-volatile parts. The conductivities of emulsions made with ester-type surfactant were less than those made with ether surfactant (Table III). Conductivity increased in both cases in the presence of urea. The conductivities of non-volatile parts of emulsions were lower than those of corresponding emulsions.