BASIC PRINCIPLES GOVERNING THE FORMATION OF HIGHLY STABLE CONCENTRATED EMULSIONS

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80-00809A000600270731-0
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 3
• Document Creation Date: December 22, 2016
• Document Release Date: September 15, 2011
• Sequence Number: 731
• Publication Date: January 3, 1950
• Content Type: REPORT

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CLASSIFICATION CONFIT.C44NTIpL ~t1~~Isr~'~.1~~~~~
CENTRAi. INTE!_LIGENCE AGENCY REPORT
INFORMATION F'?~1M
FOREIGN [30CUMENTS OR RAnlO ?ROFk?CA5T5 CD NO.
Scientific -Chemistry
Bimo7uthly periodical
N,oscow
Jan~E'eb 1948
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YIt{TYD YY LAp. p[IRGOnCTOY 01 TNI[ IOYY 19 ItOMIY1TLD.
DATE DISC., Jars 1950.
NO. OF PAGES 3
SUPPLEMENT TO
REPORT NO.
THIS IS UNEVALUATED INFORMATION
BABTC PRIAICIFIdSS GOVffi2NI14G THE FORMATION
OF HIGffiY 8TAffi.E CONCEATRAT3D ffid1ISI0AS
The factors governing the stability of concentrated emul$ione are stable
protective films, small; drop size, end the ability of the drops to ezecnte
Brownian movement. Ae Ire showed ee~rlier (1935 -1936), in. a .hS~2r1.Y :oacentrated
emulsion, when moat drops are one rpicron is diameter, high stability depends
upon the formation of structure due to the profimm4t,; of the 9lbsdsg3:y defeiwed
drops. Our laboratory btndies on highly. oonoeHtrrted,-gelat3al3sA -es~s~orm,
e.g.,`265 cubic centimeters of bens{ol in one centiaeter ,of 51~peroenL?aodlwi
olente solution, shave that a tough film covering can mnintain.ataldlity for
mend months and that any disturbance of the oell val~.a .or .ha~sgoa~ba-sasses
the emulsion to break down. 9uoh esulsi~om oea,Ds s~-ebil~i~aed~ b3 !a'ebe}~B
t`se layers with a critical thickness of 0.01-micron sodi~ a7lestie-?ecds~ttlam;
which has lea r--?-ta.ca `o breakdown. 3uoh an emnl:alari,..therefare,.,.le:sae3.1~
broken dawn by slusking with an ezcese of orgaaio. ligni?C. fihskSag with eaversl
drops of venter, hwever, not only prevente.breakdox+- of.tha etwlsl.on but alsa-..
re-establishes the, emulsion because eddf.tion of water inc7ihasee the distance
beSxaen the drops. If s greater nrpount of water is added, a dilate emulsion
le obtained.
According to Rebinder's work in 1926 - 1930 and 19~b - 1938, the condi-
tions necessary for stability in concentrated emttleioni~are adequate surface
activity of soluble emulsifiers and etabiZity of the_sdsorption lager. But
if there ie a considerable number of .lai4ge drops witL?out Brownian movement,
uniform distribution ie dietntHled and interphase layers appear, due to insaf-
ficient i>linetic stability. -
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between th?' dzop ~xnder the circo~atances, the laver walls of the atructu_~?e
moat be eteong enaugu to support the drops, according to Talmud a..d Brasier.
Br?aler'a so~caYl6d "epumoid" atracturea in dilute emulsion in such $ way Ll~t
the movemezrt of drops is impeded.. To brine about a aud.den increa?a in a con-
the cells to b'rask and the Arops to coalesce. Only thixotropic aolutleno of sir-.
face-activo sulbetancea can cover drops with a protactiae layer, even when the
network between the drops is disrupted by shaking the ?asalsion. Hence, although
amuleif'.caticn moat na.caaeari?.y first disrupt the spatial structures in the
stabiliiing solution, separation into layers ehou~d tee prevented by instanteneoua
An emulsion becomes kinetically stable for long periods if the structural
absorption layers on the dispersed drops era rapidly connected by atre:ctural ip?ee- _
solution fragments during repeated gelatinization. The struc~ure should be easily
dioturbed by mechanical emnleification in order to overcome resistance without u~-
ing large energies.
These s,,ctams should be studied and characterized by meaau_-ing the 'c'iacoeity
of solutions ar. ~az?Soue pressures and flow velocities. '~e employed such studi~a
to obtain very stable emulsions by using thixotropic solutions. In this connec-
tion we shall briefly describe our expsriments with the ~tablliain3 properties of
sodium oleate with aliphatic alcohol tc obtain concentrated emuyeiona:
Benzol was the dispersed phase. The alcohol wee mixed either with benzol or
a one-percent soap. solution. Viscosity was measured by Oatwald's viscoeimetar in
Sroyt's apparatus; surface tension, by Rebinder'e maximum-drop and bubble-pree~aure
method. Rmaleiona were made by stirring stabilizer solutions with benzol by means
of a 4GQ-rpm agitator for 5 alrnxtes. Stability was determined by the emalsion's
rate of layer formation in graduated cylinders.
Oar research showed that alcohol in benzol or soap solution geaerally increases
the ai:ability cf o11-water typo emulsions. Stability Se higher, (1) tie higher
the quantity of a1c~.7ho1 of ax~y chain length, and (?) the longer the chain for
equal alcohol concentrations. The epatiai stractt..as of solutions containing
.sodium oleate and the ffiddle members of the homologous aeries of aliphatic alcohols
axe rather fragilr~, but the emulsion's stability ie considerably increased. Cetyl
alcohol, however, bz?inga an exceptionally abrupt increase in stability when used
in benzol or soap solution. In fact, ae small a quantity as 0.1 percent of catyl
alcohol in a one??parcent sodium oleate solution is sufficient to farm an em?laion
which is practically nonaeparatiag for Iong periods. With increasing alcohol con-
tent, the emulsion beca~mes stable without limit and nonaeparRting for a year or
longer if stared in tightly closed containers. 7n this com-ectioa, we cannot
nadersta~d Shuman and Cockbain's reference to the very poor stability of emulsions
'prepared with the aid of sodium oleate and containing cetyl slc~hol in the o11
phase. Their attempt at a theoretical proof of thin le also not clear,
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~e obtained 9laoometrio rdsnlts cn soap aolntiona as a functlon of
catyl-alcohol content, in the form of ~Srves of re3.ative viscosity at 20
degrass centigrade plotted against pressure. Our data showed that is a
sodlnm oleate aolntion, cetyi: nlcohol forms spatial atructnres xhicta are
strax~sr tha higher the-alcohol concentration; Thus, xe can ass that tha
spatial atructnres deg' Loped 1u the eolutiou axe party distnrbsd at lncreaaed
flow rates but are rapidly re-eatabllehed during states of rest. In affect,
Tor alcohol concentrations np to cne percent, the spatial structure is fully
restored almost lmmediataly after dimruptlon brought about by *orcing the
solution thrargh fine capillaries. iPith less than 0.1 percent ei elc~lhol,
structure formation is not observed in soap aolntlona; also, thea~e ec~ttiuna
do not shox any increase in stability of the g~xlalon. Solutlona xeaker
than 0.06 percent do not 1?struotvriz?" and 8e not influence stability.
Temp?ratnre hew bean Shown tc influence structure formation, which
increases xith decrease irx temperature.
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