Measurement of combing forces by xiuliliaofz

VIEWS: 58 PAGES: 14

									      Cosmet.
j. Soco    Chem.,37, 111-124 (May/June 1986)




          of
Measurement combingforces

Y. K. KAMATH       and HANS-DIETRICH         WEIGMANN,        Textile
      Institute,
Research               NJ
               Princeton, 08542.


       April 22, 1985.
Received


Dedication


          is      to       Helmut
Thispaper dedicated Proj•ssor                   of
                                Zahn ontheoccasionhis
70th birthday.

Synopsis
                                          for
A doublecombmethodhasbeendeveloped the determination combing   of             for            and
                                                                         forces hair tresses, the
      of
effects environmental  humidityhavebeenstudied.The origin of the midlengthand end-peak      forces is
          and                  of
discussed, the contribution comb-hair                                                  to
                                            frictionto the midlengthforcehasbeenshown be smallas
          to                         No
compared fiber-fiberinteractions. significanteffectof environmental       humidity on midlengthand
                                              On
end-peakcombingforceshas been observed. the other hand, wetting the tressresultsin a drastic
        in
increase the midlength forceand a concurrent               in
                                                  decrease the end-peakforce.It appears  that surface
tensionforces                                                             for
             involving the liquid film betweenfibersare largelyresponsible this behavior.



INTRODUCTION

Combingis an importantmethodof groominghumanhair, basically             involvingparal-
lelizationof hair fibers. The useof liquids (suchas hair oils), which form films on the
             as                          the        of
hair surface, groomingaidsfacilitates process combing.Theseliquidsplay the
dual role of holding the fiberstogetherby surface  tensionforces  and lubricatingtheir
surface, thus reducinginterfiberand comb-fiberfriction. One way of characterizing      a
               in
hair assembly terms of the easewith which a comb can traverse           through it is to
         the
measure forceand the energyrequiredto pull a combthroughthe assembly.              Such
combing   parameters                             of
                     wouldpermit the evaluation hair careproducts      that areintended
to improvecombability.
One of the early attemptsto measure                for                 was
                                     combingforces a hair assembly madeby
Newman et al. (1). The method basically                             of
                                         involvedthe measurement the forcere-
              a                             and
quiredto pass combthrougha hair assembly wasprincipallyusedto compare          the
conditioning effectsimpartedby differentcommercial   formulations.Although factors
suchas comb-hair and hair-hair friction which contribute to the combing force were
          the                        of
discussed, natureand significance the combing      forces         in
                                                          obtained these  measure-
                       in                                             by
mentswerenot explored anydetail. An indirectmethodwasdeveloped Waggoner
andScott(2) in which the soundgenerated  during combingwasamplifiedand usedasa
        of                      of
measure conditioningand ease combing.First attemptsto explainthe natureof
                                                      of
the combing'forcecurvesobtainedduring the passage a comb through a hair as-
                                               111
112             JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS


                                               (3),
semblyweremadeby Tolgyesiand co-workers who useda methodsimilarin prin-
                                                        of
ciple to that of Newman et al. (1). During the passage the comb throughthe hair
assembly,  the force remainedat a low steadylevel for the most part but suddenly
          to                                        the
increased a peak value as the combapproached free end of the hair assembly.
Tolgyesireferredto theseforcesas midlength (ML) and end-peak(EP) forces,respec-
                                    that
tively. The fundamentalprocesses contributeto the midlength forceare hair-hair
and comb-hair   friction and the forcerequiredto compress                  into the
                                                          smallfiber bundles
spaces                                                                as
       betweenthe teeth of the comb. The end-peakforceis produced the resultof
                of
entanglements the fiber endswith oneanother.Tolgyesiand his co-workers       clearly
               the            of                                         a
demonstrated association freefiber endswith the EP forceby combing hair tress
madeof two differentfiber lengths, in which casetwo forcepeakswere obtained:one
relatedto the shortfibersand the otherto the long ones.More recentlyGarciaandDiaz
                          to             the            of
(4) usedthis technique characterize effectiveness various         conditioningtreat-
mentsin improvingcombability.
Although a considerable amountof work hasbeendonein this areafrom the point of
                            no
view of productdevelopment, detailedstudyof the methoddealingwith the effects
of environmental           on                  is         in
                 conditions the combingforces available the literature.There-
                                                                       factors.
fore, an attempt has been made to studythe effectof variousenvironmental
Furthermore,the method has beenmodified to minimize the effectof entanglements
and to maximizethe effectof surface          on
                                   treatments combingforces.


EXPERIMENTAL

MATERIALS


All measurements    were made on Europeandark brown hair suppliedby De Meo
          of
Brothers New York. Hair samples        were cleanedeither by Soxhletextraction  with
                                 in
methanol/chloroform/methanol, that order, or by washingwith a 2% solutionof
sodiumdodecyl                         the
                sulfate.In both cases, samples   weresubsequently  rinsedthoroughly
                                           at
in distilled water, dried, and conditioned 65% RH and 21øC. Tresses       were built
                    by
from thesesamples gluing the fibersto a plastictab. Carewastakento preserve      the
naturalcurl of the hair, and fiberswerealignedprior to gluing to minimize the forma-
tion of severetangles.Unlessmentioned             the
                                        otherwise, fiber endswereanvil cut with a
razorblade. The tresses  were about25 mm wide and 200 mm long, containing      about
2- 2.5 g of hair.

METHOD      I


                                                          in
Two differentmethodshave beenusedto determinecombingforces this investiga-
tion.    In the first method   the hair tress was mounted   on the crosshead of an Instron
tensiletesteras shownin Figure 1. A hard rubbercombwith 16 teeth/25mm was
mountedon the load cell. Only 25 mm of the centerpart of the combwasusedfor
insertion of the hair tress and this area was marked with adhesivetape. A smooth
retainingbar wasusedto preventfibersfrom slippingout during the measurement.    The
tress            to
     wascombed removesevere       tangles and wasthen introducedinto the teethof the
                                    and             in
comb.The loadcell waspreloaded, the reduction loadwasmeasured the tress  as
waspulled throughthe combat a rate of 8.3 mm/s. An environmental       chamber  was
usedto controltemperature    and humidity during the measurements.
                        COMBING      FORCE   MEASUREMENT                         113




                                          Lood       Cell




                                                                      Comb




                     Instron Crosshead
                             arrangement measuring combingforces a hair tress.
         Figure 1. Single-comb         for       the           for



METHOD    II


The second                        to          and
            methodwasdeveloped precomb alignthe tress           automatically prior to
                  of
the measurement combingforce.As shownin Figure 2, the hair tressis mountedon
the load cell and two combsare mounted 100 mm apart on a frame connected the    to
crosshead.  Both combsare providedwith retainingbars, and as described      above,25
                                                                        the
mm of the centralpart of eachcombwasused.With this arrangement, lowerhalf
                        is           and             by
(--100 mm) of the tress precombed detangled comb 1 beforebeingcombed               by
comb2. The natureof the combingforcecurveobtainedby this methodwill be dis-
cussed                of
        later. Because the removalof tanglesby the first comb, the combingforce
          by               is                             in
obtained this technique morelikely to reflectchanges the surface        characteristics
of the fibers.Sinceelectrostaticchargebuild-up is a kommon             in
                                                            occurrence the combing
of a hair assembly           at
                   especially low humidities  (5), a sealedradiation       (c•,
                                                                    source [3, and
                                                                    to
'y radiation)was kept closeto the hair tressduring the measurement preventcharge
build-up.
114                 OF          OF      CHEMISTS
             JOURNAL THE SOCIETY COSMETIC

                                                       CELL
                                                    LOAD



                                                       I    COMB   2




                                                       i    COMB




                                      INSTRON   CROSSHEAD

                  Figure 2. Comb holderfor double-combcombingforcemeasurements.



                      of
Twenty measurements combingforcewere obtainedon eachtressundereachcondi-
tion. Averagesand standarddeviationswere calculatedusing the logarithmsof the
                        the
combingforcesbecause distributionof theseforceswas slightly skewedtowards
highervalues.In all cases,             limits are given.
                          95% confidence

RESULTS    AND      DISCUSSION



COMBING   FORCE    CURVES


A typicalcombing   forcecurveobtained usingmethodI with a singlecombis shown  in
Figure3. The forcelevelremains                        of
                               low during the traversal the combthroughthe tress
                                                 is        at
(midlengthforce,ML) until the freeendof the tress reached, whichpoint the force
increases sharply(end-peak                                  as
                           force,EP) and dropsprecipitously the combclears   the
tress. The fundamental         that
                       processes give riseto the midlengthforce are: 1) comb-hair
                        of
friction, 2) compression fibersinto the spaces        the
                                              between teeth of the comb,and 3)
            of        as
separation the tress the teethof the combmovethroughit. The latter two pro-
cesses                 of                                              In
       containelements fiber bendingand interfiberfrictionandadhesion. the case
of wet hair tresses,eventhoughcomb-hairand hair-hairfrictionmay be reduced    by
           swelling the fibers the forces
lubrication,      of          and           necessaryseparate
                                                     to     fibers     the
                                                                 against
      tension
surface           of
             forces the liquid holdingthe fibers        can        leading
                                                together predominate,
                     in
to an overall increase the midlength force.
The end-peak forceresultsfrom entanglements  formedby the freefiber ends.It is not
clearto what extentagainst-scale                        of
                                frictionand interlocking scaleedges  contribute to
the end-peak                              can              in
            force.Interfiberfrictionforces be significant this region    becauseof
highnormal forces         the       in
                 between fibers theentangled               In             in
                                                    regions. experiments which
        was
the tress combed    priorto measurement,  end-peak       are
                                                   forces significantly lowerthan
in thosecases wherethe tresses  were not precombed.                   is
                                                     Thus precombing obviously
                          COMBING       FORCE        MEASUREMENT                               ! 15



COMBING           FORCE
           (mN)




 I00



                           I                     I                   I                     i
       0                  50                    I00                 150                  200
                                        DISTANCE (rnrn)
                                                                                        traversed
Figure 3, Combingforcefor an untreatedhair tress(20 cm) at 65% RH asa functionof distance
by the comb(singlecomb).


                 the          of       forces combing compared the
usefulin enhancing contribution adhesive    in       as      to
      of
forces fiber disentanglement.
COMB-HAIR    FRICTION


                                     the
An attemptwasmadeto determine magnitude comb-hair  of           frictionand compres-
sionusingthe arrangement    shownin Figure 4a. Basically,                   is
                                                          this arrangement similar
to that in Figure 1, with an auxiliarycombmountedon the frameof the Instronbelow
the measuring                            to
               combwhich is connected the load cell. The hair tressis carefullyput
into thesecombsso that the samefiber bundlespassthrough the spaces        betweenthe
                                as        in
alignedteethof the two combs shown Figure4b. The lowercombcompresses             the
               its
fibersbetween teeth, andthese      prealignedfiberbundlesthenpass   throughthe spaces
         the
between teethof the measuring       comb.This fiber bundlearrangement            the
                                                                        eliminates
tressseparation              to
                contribution the midlengthforce,andthe uppercombthusmeasures
                   of
mainly the forces comb-hairfriction and compression.
                                                   is
A typicalforcecurveobtainedfrom this measurement shownin Figure5. The average
midlength force read from these charts is significantly lower than that observedin
Figure3 (the tresswasthe same),and the end-peak  forceis almosteliminated.To seeif
tresslength had any effecton theseforces,measurements                      of
                                                       were madeon tresses three
different lengths. Midlength forcesobtainedwith and without the second    comb are
shown in Table I.

The data in Table I indicate that comb-hair friction constitutes about half of the mid-
                                             As                  the
length forceobtainedin a singlecombmeasurement. would be expected, mid-
                          of
length forceis independent the tresslength.
116               JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS


(a)                           Cell
                           Load
                                                                                Combs




                                             robs




                           "•
                        •'•1"[             Frame
                                      Instron
               Instron Crosshead
                     sketchof apparatus measuring
   Figure 4. Schematic                for                              arrangement).
                                                combingforce(prealigning


END-PEAK       FORCES


As mentioned   earlier, the end-peak                to
                                    forceis assumed arisemainly asa resultof tangles
                                                 the
formedby the fiber tips asthe combapproaches lastfew millimetersof the tress.If
                 is
thisassumption correct,tress                  not
                                 lengthshould haveanyeffecton the end-peak     force.
In an effort to checkthis hypothesis,  end-peak forces              at
                                                       weremeasured threedifferent
                             the
tresslengthsby changing positionof combinsertion         alongthe length of the tress,


COMBING FORCE
           (iN)
      120 -



       80-



      40




           0                     5o                 i00                 150

                                      DISTANCE       (ram)
                                                hair tress(20 cm) at 65% RH as a functionof
Figure 5. Combingfbrcefor an untreated,prealigned
                 by
distancetraversed the combs.
                          COMBING    FORCE          MEASUREMENT                          1 17


                                           Table     I
               in           of
 MidlengthForces the Combing a Hair Tresswith andwithoutAuxiliaryComb(65% RH, 2 IøC)

                                  Midlength Force,                   Midlength Force
     TressLength                    SingleComb                     with Auxiliary Comb
        (mm)                           (mN)                                  (raN)

         100                        38.2   -+ 2.9                      20.6 -+ 3.9
         150                        33.3   -+ 2.0                      20.6 -+ 2.0
         200                        36.3   -+ 4.9                      18.6 _+ 2.0




                       the                         the
ratherthan by shortening tress,soasto avoidchanging natureof the fiber ends.
The data are shown in Table II.

The data in Table II indicatethat the end-peak               to
                                                 forceseems dependon the combed
         up
distance to a certainlength (in this case150 mm), beyond                       is
                                                              whichthe increase not
statisticallysignificant. This suggests that up to a point the nature of the tangles
                                        on
formedduring combingis dependent the distance                                   or
                                                        the comb has traversed, in
other words, on the length of the free end that can get involvedin entanglements.
If the end-peak                   to
                 forceis assumed be a resultof interfiberfriction, then its magnitude
                                                      at
F is given by the summationof the frictionalforces pointsof contact,fi = Ri
                                                     R
wherefi is the frictionalforceat the point of contact, i the normalforcebetweenfibers
                                                 of
at the point of contact,and Ix is the coefficient friction:
                                              i
                                     F = • niR po.                                       (1)
Sincein a hair tressthe numberof pointsof contactis somefunctionof the numberof
fibers, n = f(N), wheren is the numberof pointsof contactand N is the numberof
      and   n                  end-peak
fibers, since = •nl, the average          per             is
                                      force pointof contact givenby

                                  • n i•    niR
                               • __ niR _ • fiN) i Ix                                    (2)
                                     the
The natureof the functionthat relates numberof fibersto the numberof pointsof
       for
contact a dense             is                        the
                   assembly not known.For this reason, numberof fibersin the
                                                            a
tresshasbeenusedas a normalizingfactorin this work, assuming linear relationship
betweenn and N (n = kN). Sincefor a given tresslength the numberof fibers is
            to
proportional the tressweight, midlengthand end-peak       havebeennormalized
                                                     forces
by the weight of the tress.
                                            of
The importanceof fiber ends to the existence the end-peakforce is seen in the
combing            for
       forcecurves taperedtresses   shownin Figure6. The taperingwasachieved


                                           Table    II
           Forces a Function CombingDistance
    End-Peak    as          of             Along the SameTress(65% RH, 2 IøC)
          Combed    Distance                                      End-Peak    Force
               (mm)                                                   (mN)

                   100                                             194 --- 15.7
                150                                                273 + 36.0
                200                                                286 + 36.0
118                  JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS


COMBING FORCE
         (raN)




                 I                                                   Thinned
                                                                    C- {she(•rs)
         0                             50                   I00                  150             200
                                                 DISTANCE (turn)
                                                     for     hair tresses
                          Figure 6. Combingforcecurves tapered          (65% RH).



by cutting the endof the tressin the form of a V, by blendinghair of differentlengths,
                             to
or by thinning with shears producefree fiber endsall along the tresslength. The
second            is                  to                              of
       specimen probablyclosest natural long hair. The shape the combing
                                (A)
forcecurveof the tapercut tress is similar to that shownin Figure3 exceptthat the
end-peakforcehasbeendrasticallyreduced.In this casethe numberof fiber endsen-
countering  the teeth of the combat any instantand the opportunityfor entanglement
formation between   fibersof equallengthhavebeendrastically           as
                                                             reduced compared a   to
tresswith a flat cut end. The sameis true for the tressmade up of fibersof different
lengths(B); the various  forcemaximain the curvefor this tressindicatepositions where
the comb encounters free fiber ends. And the same is also true for the tress thinned with
shears (C).


EFFECT    OF MOISTURE        ON   COMBING   FORCE


Midlength and end-peakforces            by
                             normalized tressweight are shownin TablesIII and
                  madefrom the same
IV for four tresses                           All            were
                                   hair sample. measurements donein the
environmental chamber. For "wet with water" (XVXVXV)measurements,the tresswas
      with a mist of waterandcombed spread evenly.
sprayed                            to    it
                 a                      in                            hu-
Table III suggests trend towarda decrease midlengthforcewith increasing

                                                    Table     III
  NormalizedMidlength Forces                                          at
                            (mN/g wt of Tress)for UntreatedHair Tresses VariousHumidities
                                            (28øC,TressLength140 mm)

                                                    RH(%)

         Tress                    30                  65                 90            WWW*

             1                 18 _+ 2              12 _+ 2            11 _+ 1         23 -+ 5
          2                    15 -+ 3              13 + 2           17 _ 1            36 + 7
          3                    19 -+ 2              12 _+ 2          14 + 3            48 _+ 6
          4                    19 + 2               18 + 4           13 -+ 4           36 -+ 4

 Wet     with    water.
                            COMBING    FORCE MEASUREMENT                               119


                                          Table   IV
                                 (mN/g wt of Tress)for UntreatedHair Tresses Various
          NormalizedEnd-PeakForces                                         at
                            Humidities(28øC,TressLength 140 mm)

                                          RH(%)

        Tress               30             65                 90             WWW*

          1              192 ñ 21       175 ñ 22           130 q- 16         51 ñ 4
         2               307 ñ 44       238 ñ 23           221 ñ 23          56 ñ 7
         3               241 ñ 15       227 ñ 33           232 ñ 36          46 ñ 3
         4               305 ñ 18       262 ñ 22           293 ñ 49          39 ñ 3

* Wet   with    water.




                                                             to
midity. Sincethe extentof swelling,which would be expected contribute theto
midlengthforce,changes little in this relativehumidityregion(30-90% RH), the
observeddecreasingtrendin midlengthforce                     to        lubrica-
                                           may be attributable increased
tion by surface                              When the tressis wetted, however,
                moistureas humidity increases.
                    increase the midlength
thereis a significant      in                                  that
                                          force.The threefactors arelikely to
           to            are          in
contribute thisincrease 1)increase hair-hair             due
                                                friction to swelling    (deforma-
                  to
rive contribution friction)and/orin hair-combfriction,2) higherforces requiredto
packswollen                the
              fibersbetween teethof the comb,and 3) forces            to
                                                             required separate
fibers               by
      heldtogether surface          forces.
                              tension     Since                    of
                                               thereis a possibility lubrication
                           contributions themidlength
by theliquidfilm, frictional           to                   are
                                                       force likelyto besmall,
        the                 to                        to
leaving othertwo factors be the majorcontributors the midlength        force.
                                                                is        as
As to the end-peakforces,on the other hand, a significantdecrease observed a
                               the      are
resultof wettingthe tress.Since tresses combed            the
                                                   before combing   forcemea-
                      in                        the
surement,this decrease end-peakforce reflects, fact that the fibers have been
alignedduring pre-combing                                  by
                          and are held in that configuration the surfacetension
     of                  the
forces the liquid between fibers.Thusthe majorforce             for
                                                       responsible the decrease
              forces the virtual elimination entanglements. lessimportant
in the end-peak     is                      of               A
contribution                      lubrication the liquid film.
            may comefrom interfiber          by

WET   COMBING


The "double   comb"apparatus             in
                              illustrated Figure2 wasusedin this investigation.
Typical combing         for
                  forces "dry"hairtresses                    in       7.
                                           (30% RH) areshown Figure During
the initial part of the measurement, both combs slidethroughthe tress,giving the
combinedmid-length forceML-1,2. Comb 1 is the first to reachthe end of the tress,
giving riseto the end-peakforceEP-1 asthe freefiber endsmovethroughthe comb.
                               the      for          of
Only comb2 is now traversing tress a distance 100 mm, givingthe mid-
                                                                          the
length forceML-2, which is slightly smallerthan ML-1,2. As comb2 reaches end
            it         the
of the tress, generates second    end-peak force                          smaller
                                                EP-2, whichis significantly
than EP-1. As would be expected,                          to
                                  EP-2 wasalwaysobserved be smallerthan EP-1
because                           have
         mostof the entanglements beenremoved                         of
                                                    duringthe passage the tress
                               of
through comb 1, and the release the free tressend from comb 1 under controlled
         leads the formation fewerentanglements a morereproducible
conditions   to            of                  in                  manner
than any manualprocedure.The extent of suchcontrolledentanglementformation
       on
depends the spacing between      1
                           combs and2, shorter distancesgivinglessentangle-
120              JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS

COMBING FORCE
         (raN)
 3000--


                                        EP-i

 2500




 1500



  I000

                                                                            EP-2




                 ML- t,2                               ML-2
                           50                  I00             150             200
                                                 DISTANCE (mrn)
                                                for
                    Figure 7. Combingforcecurves untreatedhair at 30% RH.



ment and thus lowerend-peak         A       of                   for
                              forces. spacing 100 mm waschosen bestrepro-
ducibilityof EP-2, whichis a muchmorereliableproperty                   EP-1
                                                     thanthe unpredictable
                                   in            hair      and
and canthus be usedadvantageously characterizing tresses hair careformu-
lations.

Combing force curvesfor a hair tressat 65% RH and for the sametressin the wet
conditionare shownin Figure 8. At 65% RH, small midlength forces   ML-1,2 and
ML-2 are observed,with relativelyhigh end-peakforcesEP-1 and EP-2. As discussed
     wettingthe tress
above,                    a             in                  and
                     causes largeincrease the midlengthforces essentially
                    of
completedisappearance the end-peakforces.
Wet combingof Negroid hair shows     the opposite behavior:wet combingforces   are
                    for            (6).
lowerthanthe forces dry combing Extreme                 of
                                                curliness the fibersprevents them
                         by
from beingheld together surface   tension       of                          do
                                          forces the liquid whichtherefore not
                      to
makeany contribution the combing      forces(midlength).Furthermore, reductions in
        and bendingmoduli lead to a loweringof the wet combing
torsional                                                          force.It canbe
assumed that torsional                          to
                      and bendingcontributions the midlengthcombing       forcesof
Caucasian hair are minimal and that surface tensionforcestherefore make the major
            to
contribution the wet combingforce(midlength)of Caucasian     hair.
                         the          of
In an effort to establish contribution surface              to
                                              tensionforces midlengthand
end-peakforces,combingmeasurements  were madeon a tressat 65% RH, after wet-
                             COMBING        FORCE MEASUREMENT                              121


COMBING FORCE
        (rnN)
                                                                             COMBING FORCE
                                                                                 (mN)

                                                                                   - 2000


                       .........
                         .^•%.,
                    ..?'"'
                                                                                    - 1500
        •.- H20

                          i•
                       GAF-755                                                          !000



                                                                                        5OO




    0                  50               I00                    150     200
                                       DISTANCE        (ram)
Figure 8. Combing forcecurvesfor a hair tresswet with water and a 1% solutionof GAF-755 (left
                                                 alongthe abscissa.
ordinate).Curvefor GAF-755 is arbitrarilydisplaced               Curvefor the sametressat 65%
RH is alsoshown(right ordinate).


ting with water, and after wetting with a 1% solutionof Triton X-400 (TR-X-400), a
                                                    in
quaternaryammonium surfactantusedextensively hair conditioners          (Figure 9). A
considerable           in                   is         on
              decrease the combingforces observed loweringthe surface          tension
of the liquid (water:72 raN/m; 1% TR-X-400:27 mN/m). The combing           forcecurve
for the tresswettedwith a 1% Gafquat-755(cationic    polymer)solution        in
                                                                      shown Figure
                                               The
8, on the otherhand, doesnot showa decrease. surface               of
                                                           tension the Gafquat-755
solution(67 mN/m) is similar to that of water. Theseexperiments   appearto reflectthe
significantrole that surfacetensionforcesplay in the wet combing of hair tresses.
                                                       of
However,it hasbeenpointedout that the substantivity Triton-X-400 to hair reduces
                of                                             in
the coefficient friction of wet hair (7), so that the decrease combingforces     after
wettingwith Triton X-400 maynot be dueentirelyto the decreased     surface tension. As
a matter of fact, preliminaryexperiments with nonsubstantive  surfactantsolutions (1%
                                                             in
sodiumdodecylsulfate)did not producesimilar reductions combingforces.This
aspect will be exploredin more detail in a future investigation.

COMBING     FORCE   MEASUREMENTS   DURING     HAIR   DRYING


Blow drying wet hair with hot combsis becominga widely usedgroomingtechnique.
The processinvolvescombing the hair while continuouslyremovingmoisture. These
conditionswere simulatedby combinga wet tressat variousintervalsof time in the
           chamber 60øC.Combing
environmental    at            force     for          up
                                    curves time periods to 0.3 ksare
shownin Figure 10. End-peakforces              at                    a
                                 beginto appear about0.3 ks, reaching peakat
                  the
0.4 ks, suggesting removalof mostof the water held by surfacetensionforcesand
          of                     interactions form entanglements.
the release free endsfrom adhesive          to                   Note that the
combing force curve at 0 ks showsa small end-peakforcewhich is not observed in
122                  JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS

                                                                                                COMBING FORCE
                                                                                                         (mN)-         3000



                                                                                                                  -    2500
   FORCE
COMBING  (mN)

                                                                                                                  -    2000



                                                  •-65%R            H
                                                                                                                  -    1500


                 H                            ,
                                                                                                                  -    I000
   -II                                    ;
                                          I       I
                                      /
 I00                                                                                          ,,'\--•-            -    500



                            I
    0                      50                         I00                       150               200
                                          DISTANCE (mm)
Figure 9. Combing force curvesfor a hair tresswet with water and a 1% solutionof TR-X-400 (left
         Curvefor the sametress 65% RH is alsogivenfor comparison
ordinate).                     at                                    (right ordinate).



COMBING FORCE
         (mN)
       12(




                           ks




                                0.12 ks

                                                        .:'

             Ill           /0.18ks._./'--'-':/•':.-'%,
                                                  ...'"'
             II/.      ............. ""-A 3 k                 ' '-' "-'                   "' ......
             •'/' I              I                I                   I
                                                               I.........             I
             0                  50                            I00                     150                        200
                                                      DISTANCE          (ram)
                  force  for         during
  Figure10. Combing curves a hairtress    drying 60øC
                                               at        various
                                                     after          times.
                                                               drying
                                COMBING       FORCE MEASUREMENT                           123


combing            obtained 0.12 and 0.18 ks. This end-peak
         forcecurves       at                             forcemustbe dueto
                                  has
a ratherunusualtangleand therefore beenignored.
The variationof midlength and end-peak     forcesduring the drying of the tressis shown
in Figure 11 asa functionof drying time. As canbe seen       from Figure 11, the levelling
off of the midlength forceand the maximum in the end-peakforceoccuralmostat the
                                        to
sametime (--0.4 ks), corresponding the removalof extraneous             moisturefrom the
                                                                            the
tress.Further drying hasvery little effecton midlength force, whereas end-peak
                 to          at
forcecontinues decrease a slowrate, presumably           reflectinga continuous improve-
ment in fiber alignmentduring successive    combings.                       the
                                                        This againsuggests contribu-
tion of surface                 of
                tensionforces the liquid to the midlength combingforce.Their con-
tribution to the end-peak  forceis indirectin that the surface  tensionforcespreventfiber
entanglement,thus leading to a lower end-peakforceor completeelimination of the
end-peak   force(as in this case)  dependingupon the methodusedto measure       combing
forces.



CONCLUSIONS

Results         in                              of              in
        reported this paperand the observations earlierworkers this field clearly
                                   make major contributions midlengthand end-
indicatethat interfiber interactions                       to
                     in
peakcombingforces hair tresses.    The contributionof comb-hairfriction to the mid-
                                                             in
length forcehasbeenshownto be relativelysmall. An increase humidity seems        to
                           in
result in a small decrease midlength forcedue to the lubricating effect of surface
                                                      the
moisture.On the other hand, wetting the tressincreases midlength forceasa result


COMBING FORCE
       (raN)




 160 -


                                                                     EP-2    (End-peek)
  120
                                                                                             o




  8(




  4O

                                          x
                                                                     ML-2 {Mid length}

   0 •-o-•                  I         I          I      I x---x I        I        IXX4'x--I
                      0.8            1.2        1.6    2.0     2.4     2.8       3.2       :3.6
                                                 TIME (ks)
                              (EP-2) andmidlength(ML-2) forces
Figure 11. Variationof end-peak                              duringthe dryingof a hair tressat
60øC.
124             JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS


                                                  of
of swellingof the fibers,which makesthe compression fiber bundlesbetweenthe
                                                  the
teeth of the comb more difficult, and alsoincreases forcerequiredto overcomethe
surface              of
        tensionforces the liquid film which hold the fiberstogether.Wetting the
hair assembly  resultsin alignmentof the fibersby the surface                of
                                                               tensionforces the
liquid film after elimination of entanglements.  This leadsto a drasticreductionin
end-peak  forceto which entanglements    make a major contribution.The reductionin
wet combing   forceswith surfactant solutionssuggests the surface
                                                      that          tension     of
                                                                           forces
                                       to                                are
the liquid makea definitecontribution the midlengthforce.Theseeffects further
           by
confirmed the observed             in
                          decrease midlength    force increase end-peak
                                                      and       in          forceas
a resultof removing  capillarymoisture  from a wet tresscombed duringthe process of
drying.


ACKNOWLEDGMENTS

Thesestudiescomprised  one aspectof work on the Textile Research Institute project
                                                     by
"Studiesof the Modificationof Human Hair Properties Surface    Treatments,"sup-
portedby a groupof Corporate                 The
                             TRI Participants. authors    wouldlike to thankMs.
MargaretAnn Rogers  and Ms. Hannelore  Mark for their carefulexperimentalwork.


REFERENCES

 (1) W. Newman, G. L. Cohen,and C. Hayes,A quantitative               of
                                                       characterization combing     J.
                                                                               force, Soc.
     Cosmet.Chem., 24, 773-782 (1973).
                                                                              of
 (2) W. C. Waggonerand G. V. Scott, Instrumentalmethodfor the determination hair raspiness,J.
               Chem., 17, 171-179 (1966).
     Soc.Cosmet.
 (3) W. S. Tolgyesi,E. Cottington,andA. Fookson,           of                      at
                                                Mechanics hair combing,presented the Sympo-
     siamonMechanics ofFibroas         FiberSociety,
                              Stractares,          Inc., Atlanta, Ga., May 14, 1975.
                                                     on
 (4) M. L. GarciaandJ. Diaz, Combabilitymeasurements humanhair,J, Soc,    Cosmet.     27, 379
                                                                                 Chem,,
      (1976).
                                                properties humanhair, J. Soc.
 (5) A. C. Lunn and R. E. Evans,The electrostatic         of                    Cosmet. Chem.,28,
     549 (1977).
 (6) J. A. EppsandL. J. Wolfram, Combing            between
                                          differences                and
                                                             caucasian blackhair,J. Soc.   Cosmet,
     Chem., 34, 213 (1983).
                                           of
 (7) G. F. ScottandC. R. Robbins,The effects surfactant         on                         Cosmet.
                                                       solutions hair fiber friction,J. Soc.
     Chem,,31, 179 (1980).

								
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