• 4"' .i' ' .: •: .... • :: • • • • : - - •.d •' ' i• •'• :::. ". . • •'• •. • '• :• . ". ' .... •T ' • .. f .• . :• •¾: .•..... . . •-..• •.:• ....... • '•.• •'.' .'" .•?• •:d• ?•.: •..... ..... ':.'.• '.' -.-•'?• • •.• =• ? •.• •'='•-. ..:.'.-:. .... • .,. :•, •: : : . :• •x:..• .... •. -.• ....... •.•.: •.:•? .•=. .. .... :: ...... .....•.. • .• ?,•.,• '•= •.•:•. , ..•...•? ß . .•..•.., •.•.•:•- ?.•:•:.• .•: .:•?• • • .:..• Figure 6. Photomicrograph of a tricthanolamine stearate foam ,.•..•..•. • •. =5='.4 •. " '•' :•i: .:: ,. . . :::•. •...• "'•,.:•:•:• 5'.• :'-'. • .•.:')':': •' '::•'/: - -i':• :-.•' -=' . -..- .' .• •?•.::. ::=:•" • •:• •-• ..•'. i - .. •= .•: .•. •" =:•i•::•'" '=5 ::':•i '•:'•: Figure 7. Photomicrograph of a triethanolamine stearate/stearyl alcohol foam

822 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS The same order occurred with foam persistence. The foam with no alcohol disappeared in about 30 minutes, and that with a soap/alcohol ratio of l:l/g disappeared in one hour. The remainder became thin but retained most of their structure for over an hour. In the triethanolamine myristate/myristyl alcohol series, the first increment of myristyl alcohol had a pronounced effect upon emulsion stability, foam drainage, and foam stability but subsequent additions of myristyl alcohol had much less effect. The foam with no myristyl alcohol wetted paper in about 25 minutes, while those with myristyl alcohol did not wet paper in an hour. After two hours, the triethanolamine myristate foam had disap- peared but the remaining foams maintained most of their structure although the foams with the lower concentrations of alcohol became very thin. Variation in Propellant The effect of variation in propellants upon the properties of tri- ethanolamine laurate/lauryl alcohol systems is shown in Table XII. All of the emulsions were quite stable, and differences in emulsion stabil- ity due to propellant variations were not detected. Freon-12/Freon-11 (50/50) and Propellant 142b gave the most rapidly draining foams, and Propellant 142b and Propellant 152a gave foams with the lowest density. The foams with Freon-12/Freon-ll (50/50) propellant and Propel- lant 142b wet paper immediately after discharge, while foams with the other propellants did not wet during an hour after discharge. These results therefore correlate with the foam drainage data. The foams with Freon-12/Freon-ll (50/50), Propellant 142b and Propellant 152a collapsed almost completely within 30 minutes after discharge. Those with Freon-12, Freon-12/Freon-114 (40/60), or Freon-114, retained their structure for over an hour after discharge, although they showed surface decomposition and thinning. Variation in Soap/Alcohol Concentration The properties of triethanolamine laurate/lauryl alcohol and tri- ethanolamine myristate/myristyl alcohol systems at concentrations of 0.025 and 0.100 M in the aqueous phase are shown in Table XIII. In- creasing the soap/alcohol concentration in the triethanolamine laurate/ lauryl alcohol system increased emulsion viscosity and emulsion stability but decreased the rate of foam drainage. Foams at both concentrations showed some thinning after two hours but retained their shapes.