Correlating Porosity and Tensile Strength of Chemically Modified Hair

1. Correlating Porosity and Tensile Strength
of Chemically Modified Hair
Ali N. Syed and Hasan Ayoub
Avian Industries, Inc, Bedford Park, Illinois USA
o
....
»
s:::
Keywords en
ver the years, many individual studies have been con contact time. As explained by c:
O ducted regarding the extent of damage imparted to Feughelman, the absorption of water hairporosity, hair
tensile strength. hair
quot;quot;
en
.....
hair. These studies deal with the damaging effects of various takes place initially onto the hydro- damage, permanent
»
z
chemical processes such as permanent waves, permanent philic sites of the globular protein hair colors~ avid .....
colors and hair bleaches. !-8 matrix and on the surface of the mi- permanent waves. hair »
.....
relaxers, hair bleaches
The most commonly employed method to quantify this crofibrils. After the initial absorption, o
damage is the measurement of change in tensile proper- more sorption of water builds up on z
Abstract
ties ofthe hair. This method takes two to three days in the water molecules already attached to
preparation of samples of hair fibers. It also requires a the protein structureY According to Ibis study validates the
poroSity method against
minimum of 30 to 40 fibers for statistical analysis. There- Chamberlain and Speakman, the total the widely accepted
fore, there is a need for other simpler methods that are uptake of water is 31.18% at 100% method of tensile ::0
strength for detennining quot;'tI
equally valid and less time-consuming. humidity.!2 The uptake of water or the hair damage ::0
One such method could be the determination of hair swelling of hair can be measured by imparted to hair due to o
cosmetic treatments.
o
porosity or water uptake of hair fibers as described by two methods: the volume method or c:
o
Valko et aU and by Menkart et al.! However, to the best of the weight method. .....
en
our knowledge, no study so far has correlated the tensile Volume method: Shansky, in
strength method with the water uptake (swelling/poros- 1963, was the first person to measure
ity) method following chemical treatments such as perma- the change in the diameter of the
nent waves, permanent colors, hair bleach, and perma- individual hair fibers using a micro-
nent hair relaxers. scope. 13 In 1990, Nothen et al. de- quot;quot;
o
.....
Therefore, we have conducted a study whose purpose vised a more accurate instrument uti-
»
Was to validate the porosity method against the tensile liZing an optical unit for sensing the z
strength method. Another purpose of this study was to diameter of a single fiber, and an o
»
....
use these two methods to compare the magnitude of hair online analyzer for displaying the data
en
damage between permanent waving, permanent color- in real time.!4 In 1998, Syed et al.
z
ing, hair bleaching, and permanent straightening pro- measured real time swelling of indi-
»
cesses. Finally, this study ranked the various chemical vidual fibers using a laser micrometer z
.....
processes in terms of their hair damage potential. We that measured the major and minor
believe this is the first comparative damage ranking for axis of the fiber simultaneously dur-
various chemical processes in the hair care field. ing the immersion of the fiber in an
appropriate solution.!5
Swelling or Porosity of Hair In each of these volume methods,
Professionals who are involved in the art of styling hair the selection of the fibers takes a long
define the porosity of hair as the capacity of hair to absorb time and then swelling of each fiber
liquids. Hair that absorbs a larger quantity of liquid is said has to be measured over a 20-30
to be more porous than hair that absorbs less liquid. Hair minute period. Also many individual
stylists associate higher porosity of hair with higher de- fibers have to be used in order to get
gree of damage.!O statistically significant results. Addi-
Water is able to penetrate into hair after a sufficient tionally, this method may not be ap-
Vol. 117, No. 11 /November 2002 0361-4387/02/0011-0057$05.00/0-© 2002 Allured Publishing Corp. Cosmetics & Toiletrie~ magazine/57

2. I>ropri;ltt' for lllc:lsuring the change treatmenls if il correlates wilh most Widely accepled
in diameter of tfrican·descellt fibers methods for measuring hair d:lmage. One of those melh·
where the inherent variation in diam- ods is the measurement of tensile strength,
eter is significant within a single fiber
along the hair shah.'quot;
Tensile Strength of Hair
Weigbl melbo/I: The wdght The tensile propenies of hair fiber.!> play an imponant
method is much less tedious and has role in eJcterrnining the efficacy of hair treatments such as
the ability to study the swelling or permanent wavcs. pcrmancllt hair colors. bleaches and
water uptake of hair fibers using a permanent hair straighteners. The influencc of '3.rious
centrifuge. With thb method. a single hair tre:ltments on the tensile propenics of h2ir can be
operalOr can conduce mure Ihan 50 measured using tensile meters such as Insuon' and Oia-
measurements a day_ ,- The weight Stronquot;,I.
method is also known as the liquid One commonly used method 10 deu'rmine ifhair fibers
retention or porosity test. Valko and have been altered by treatment with cosmetic productS is
Uarnell ha'c defined I>orosity as the 10 extend the fibers 10 20quot;quot; ofthcir lengt h before and after
capacity of hair fibers to absorb wa- treatment and detemlin(' the so-called F20 Index. A single
ter.'quot; Chemically d:tma}o:ed fibers arc fiber is stretched 10 20% Strain orclongation:1I a specified
considered hrdrophilic or porulls:lnd COnSl:lnl rate (dong:llion per minute). The area under lhe
therefore would more readil)' pick up curve (Energy) reqUired 10 slrelch the fiber to 20% str:.lin
moisture :lIld retain W:llcr than the is used to assess the condition of Ihe fiber, The index
U1ureated or unmodified hair. Valko values (After/Before Treatment) :Ire e:tlculated and used
and Uarnclt believed that lhe gre:lter 10 assess Ihe extent of hair damage. An Index of less than
the porosity of hair, the greater was 1,0 indicales damage to th(' hair fiber produced by thc
the damage 10 the hair fiber, They chemical hair product. This mClhod was first den:loped
found the uptake of water for un· b)' Speakman in 1947 in order to study Ihe effects of
modified or normal hairto be 31.10%. physical and chcmical processes on kcratin propcnics.
Therefore, the poro.!>ity technique may
become:l primary method for dcter· ·llI$lmquot; Iml,.,., e.quot;por.,,_•. Omquot;'quot; ,1/'os.lIKbuJl'1b
mining hair damage due to cosmetic ·'Nt-51ron. f)k.-SltWl Uti ~Q, f·... lSlf..quot;quot;...
581Cosmellcs & To<lelll6tquot; magazine WNW TheCosmelic$'lecom Vol 117, No 11/Novembet 2002

3. Table 1. H11lr trNtmenb by commetel8l cosmetic products prior to determination of porosity and tensU,
strength of IrNhKI hlilr flberw
--
Hol,
T _ .......
-
T_ _
_....
T_
..... ...-
-- -
.... 28 g Logicquot; Permaoent Color Blond-12G AN ~1T'in TRP AN' '~NCS
--... 38 g logIC Color 0eIIel0pef (30 YO! H,OJ
77 g SyntoOCs' Mulbplex Acid Wave lotIOn AN 2O~TRP 2.51'lW'1 5~CNS 2.511'lln
18.5 g Syntcncs Wllving lIClJVator
.. ,-
-.-
Relexer GHquot;
HIIII bleach'
Alfirme No-Base ReWcer
139 g Affirm No-lye No-BMe ReIa.llerquot;
37 g Affirm liquid ActIVIIIOf
1.5 g logk: Powdef 8lee<:h
12,
12,
AN'
.. -
~
45 mlnTRPH
,-
,~
3 min
2 ITWI 2x NCNS
2 min 2x NCNS
1 min NeS
,~
1 min
9.0 g Logic COlor GeneratOf (30 vol)
quot; Rmsed wilh Wllfm funning lep waler
• Rinsed willi fUfllling laP walef
~ Rinsed until all excessive Color was gone
• Applied by bfIstl to COYEIf enlUelJes5
quot;logIC product, life manule<:tured by Malnx. a pat! of L'Oreal, Fraoce.
'Syntoruet. I, a tradernartl of Syntonics Inlematlonal. Sl.rMlII, Illinois USA.
_...-
• Affirm ia alfaclemarll of AVIan IfldustrI8S Inc. 6ec:lIofd PanI, Illinots USA.
• Affirm SensitlY'I Scalp No-Lye No-8ase Re/axef NgrmaJ Strength
I Pem'Ianenl half reiaxel' contIirWIg sodiun hydroxide
•P8m'IaoenI half relaxer contasfW1g guanidine /1ydroxIdIll
m.as~
NCS • non-<:OI'ldi.oOfWlO shampoo
eNS • condiUoning neutralizWlg shampoo
NCNS. non-condibonlng neutralimg shampoo
TAP. tress Wl'apped in plastic
TRPH • treas wrapped in plaslic and placed i,n;Ier oYerhead dryer al 55-<:
Speakman used a percentage to express the changes in hair using the methods of Spcakman lH
thc stress for a fixed strain of fibers. IH and Menkan et ai.'
Sooknc and Harris coined the tenn 30% indcx as the Therefore, in order to verify thc reli·
ratio of extension values. 19 This test is similar to the F20 ability of the porosity/Weight method,
test except that the singlc fiber is stretched to 30% strain we dcsignt.quot;d a study to com:I:lle the
or elongation. porosit}' of rum flbelquot;S at I{)(J% humklit}'
Over the laSi 50 }'(:;1rs, it has become a standard practice with the tcnsile stn:llgth of h.:Ur fibc:rs at
to ;1SCen;1in the F20 Index of the fibers bt'fore ;1nd :mer thc 100% humidity, We hypothesizc.quot;d that a
given trr.ttment in ortler to detcnnine the positive or nega· nc:gath'tquot; COITd:ttion would exist bc.:twt:t:ll
ti'e effect of the treatment on the fibt'rs, In 1966, Menkan el porosit}' and tensile sucngth. Addition-
al. compared the F20 Index of hair and wool and found hair a.lI}', we assc:.:ncd thai if the cocfficinu of
to h;1'e slightly higher no Index than wool. I detcmtination (r-) is al 0.95 or highc.:r.
In addition, man}' published studies ha'<quot; examined the then the porosity/wcight method would
changes in the tensile strength ofcosmeticall)' modified hair be considered COrn:latLquot;d and thereb}'
in the area of pcmlanent hair colors. permanent hair wavcs, established as a reliable method for fu-
and hair bleaches.~'quot; The field of pennancnt hair relaxers is tun.: USC in thc labor:uory.
not well rcsearched, although Syed et :11. have compared the 111is method will cnablt: the hair
tensilt:: strength of Caucasian hair against African·American rcsearcher to obtain rcsults that are
Vol 117, No 11!Novembef 2002 www.TheCosmel.eSile.com Cosme/icsquot; ToilfJ/fleS<- magazloo/59

4. % Porosity = {[W. - (W - 0.162Wl]IW.1 x 100
where
An,... ~ora.lquot;
W. = Weighl 01 hair Immediately after centrifuging
Trttlmtrrt frIlquot; (%)
W = weight of hair at 65% R.H.
w- O.162W is described by Mankart at aI.' Untrealed 3t.15 i:0.63 N.6
Hair colof with 30 vol develope' 32.01 ±0.12 N.S
(The average % moisture absorbed from 0% to 65% R.H. for
Acid wave 35.32 i:0.29 N:S
normal hair is approICimately 16.2%.) Hai, relaxer (NaOH) 36.15i:1.26N_S
Hair relaxer (gl.lanidine) 38.00 i: 1.1 7 N.7
ngun I. CAlrutQl/on o/port/$U,r
Hai, bleach with 30 vol developer 54.57 i:2.48 N.5
N • Number Of samp~s
bOlh fasler and reliable. This method 'See Table I for specific plquot;oducts lested.
will also allow the haif dH:Olisl to
compare I he degree ofd:lmagc impanel!
during various cosmetic treatments.
Table 3. Tensile strength of treated hair
Experimental
Trf!(llillg tI}e bquot;ir: For the poros- Anrlquot; telllll,
ity testing, all h:llr used was Callcl- T,,,lmenl quot; quot; , IIrtng1ll (mJ)
sian h,llr 8 inches long, assembled Untreated t.210i:0.1SN=60
into six tresses of equal weigh!. Till' Hair color with 30 ~ol de~eloper 1.138 i:0.20 N..41
tresses wcrc accur:ltcly weighed on ACId wave 0.991 i:0.12 N_SS
an analytical balance :114.0 gfO.1 mg. Hair 'elaxer (NaOH) 0.776i:0.11 N=53
Hair lelaxer {guanidine) 0.698:1:0,11 N..57
For lesting tht: tensile strength of
Half bleach with 30 vol developer 0.480 i:0.08 N .. 51
the hair. dark brown European-de-
scent fibers (Level 2) of 80-90 mi· N= Numbel or samples
• see Table 1 fOl specific products tesled.
crons were obtainell'- anll separ-lled
inlO six lIifferelll groups.
Of thl' six weighed tresses, one
was lefl untreated as a control, and utilizing the centrifuge method of Valko and Bametr.~ Each
each of the other tresses was sub· of tlte six tresses was dh'ided imo eight So1mplcs weighing
jected 10 one of thc following cos· 05 gram each. All samples were equilibrated at 65% rdative
metic treatmenls: permanent hair humidity and 21°C for 2 weeks prior to using.
color, acid wave. permanent hair re· To begin the porosity measurements, each s:tmple was
laxer (sodium hydroxide), permanent wdghell at 65% R.H. using a microbalance d • The samples
hair relaxer (gu:lllidine hydroxide) were immersed in 100 011 of deionized water for 30
and hair bleach. Details of these treat· minutes, removed with stainless steel forceps. and placed
ments arc presented in Table I. The into polystyrene centrifuge tubes (28 011) containing a
method oftreatment employed in c:lch mesh at the bottom of the tubes to keep the hair separate
case was the same:ls pr.u.:ticed in the from the drained water. Thc tubes were capped and
market place. centrifuged~at 7,000 rpm for 10 minutes. After centrifug-
The six sized groups were I'ro- ing, the samples were rcmoved and wcighed again on the
cessed in the same way asthe Weighed microbalance. This method prOlluccd repeat:lble results
tresses, again according 10 the details for cach of the Ire:t1ments. The porosity of hair was
presented in Table I. ca1cut:lted as shown in Figure I.
Dctermltl/quot;g 1Jalr' porosity: The Delermlt,lquot;gflber lertsile strequot;8th: The Ulltre:lted
porosity of the hair was de[ennined fibers and fibersof chemically treated tresses were crimped
at 30 mm length from the root tip and then immersed in
deionized water at 21°C for 30 minutes. Then the amount
s,·quot;,
• I A'.Ifquot;quot; IJquot;,/I,.,,,,. 1'quot;,*. ,j./t. 1'quot;,* llSA J
quot;'I'I/Iquot;r MIquot;fliJquot;,/(mf'·. ,ul'l/I,-, TuI..fo bt,lm,c,· of work required to extend the wet fibers by 20% ofthdr
mU</,1-1'(.'·HOU, ,U,-lIf,quot; ''',J,v/o Illc. Coiquot;mbu$. originallcnglh was determined on the :Htlomated tcnsile
001(, {')ojl
,. J ,11<quot;1/1<quot; MI,·mlx/Iquot;,,,·,'. ,1/quot;/1/(quot; ·1<.I<v/quot; IN/IIIIquot;'quot;
quot;'0</<1 quot;,'O/.fOO. M,1'/,'r n,J,vfo Iquot;c.• O,Jquot;quot;,bus,
lester (!'hase I = 20%; Maximum Force = 200 gmf: Num-
berofcycles= I: Gauge = 1).
• OOI,,'r.'itt
quot; quot;quot;/quot;flliI//oowl Cc'.urlfi'..~' quot;'0<1,1 (.quot;(''111quot;(1 ·t. quot;!lO'
quot;,,,tI,'/ HM. 11:quot;C 1quot;/quot;rull//(}Iwlll'/u'pquot;,,'m 'I)/il-Sm.., Milllquot;/,,,,.· T<'II5111' 7''SI,-r. f)il/-S/'W, fJd. IJrocmll,lI. 1'''''5)1/v'''/I'
...quot;quot;pm,)·. ,'quot;,v:lbquot;quot;, 1k.;p,bl,·.•IllI.<!i<.cb'....·1IJ 1JX.j
quot;'<
GO/Cosme/,cs & Toiletries'quot; magazine www.TheCosmeticSile.com VOl. 11 7. No 11/November 2002

5. -
LO
0.8
0.6
~·O.9607 ~
O'
0.2
0.0
31.15 32.01 35.32 36,15 38.00 54.57
Untreated Hair Color Acicl Wave Sodium Guanidine Hair Bleach
Hydroxide Hydroxide
Relaxer Relaxer
FJ,Il,., 2. CQ~/.,II(Jn betwlllln ptJrosU, tquot;,d tllMUII stnnglb olbnlr ',.,alf'd by .ff!/«tf'd cosmetic products
(see TAble I!tlr detflUS on the ProdllctS tested)
Results and Discussion is similar 10 the order of water uptake for l~al~h of the
cosmetic treatments in Table 2.
11 is apparent from Table 2 that
Using a statistical pack:tge~. we corrd:lIcd the porosity
untreated hair has the lowest amount
data from Table 2 and tensile strength data from Table 3.
of water uptake (31.15±O.63%, N=6)
Thc coefficient of determination (r~) was found to be
tll;lt is very close to tile value of31.18%
O.9607(Figure 2.). which isStatistically sigoificlnt. There·
found by Chamberlain and
forc, the water uptake method orporosit)' metho<.l and the
Speakman.quot; Our value of 31.15% is
tcnsile strength method arc highly correlated.
also very close to the valutquot; of
As shown in Tables 2 and 3. the orderofdamagc caused
31.IO±1.00% found b)' Valko and
by the cosmetic treatmelllS is:ls follows: Untreated hair <
narnetl.~ Therefore, our method of
Permanelll Hair Color (Golden B1onde·level 12) < Pemla-
determining water uptake is in agree-
nem Wave (Acid Wave) < Ilair Iklaxer COntaining sodium
ment with both of those studies.
hydroXide < Ibir Relaxer containing guanidine hydroxidc <
The cosmetic treatments such as
Hair Ble;lch.
permanent hair colOr, acid wave. per·
manent hair rc:la..xers and hair bleach Conclusion
impan increasingly higher water in
II is clear from this study that V:llko an<.l Barncft's
that or<.ler, as shown in Table 2. It is
weight method (water uptake) or porosity of hair is
clear that permanent hair rclaxing
significantly correlated (r'= 0.9607) to tensile strength of
and hair bleaching arc more damag-
hair when hair fibers arc chemically treated with various
ing than processes such as perma-
cosmetic trC:l(mcms.
nent hair colors and acid permanent
This study also compares lhe damage imparted to hair
waves.
fibers from various chemical cosmetic treatments such as
As shown in Table 3. untreated
permanent hair colors, acid permanelll waves. hair relax-
hair had the highest avemge tensile
ers and hair bleaches. The order of magnitude of hair
strength(I.210±O.180 m), N=60). On
damage is also determined and it is found that permancnt
the other hand, cosmetic treatments
hair colors are least damaging followed by acid permanent
such as permanent hair color. acid
waves and hair relaxers. whereas the bleaching of hair is
wave, pcrmanent hair relaxcrs and
the most damaging cosmetic treatment.
hair bleach produced incre;lsingl)'
The weight method or porosity of hair is a Jess tedious
greater rcductions in tensile strength
and less time-consuming method for cosmetic chemists. It
(to a low of0.480tO.080 m). N=51).
can be used instead of the tensile strength method to
The order of damage in terms of ten-
determine the degree or damage.
sile strength for each of the cosmetic
The porosit)' method woulquot; seem to be especi:llly
treatments is shown in Table 3 and it
convenient to usc on excessively curl)' hair in which the
Young's modulus varies signific:lIltl)' within a single hair
• 51'SS. JI'SS hlC, ChICtlJ,quot;'. 11I1quot;,,/5 UI:1
fiber due to its cver-changing diameter along the hair
62/Cosmerics & Toile/riesquot; maguine www.TheCosmelicS.le.com Vol, 117. No. Il/NOvember 2002

6. shaft. The Young's modulus is equal manent hair colors; this study was limited to only one hair
to the stress / strain, where strain is color and only a 30 volume developer. Similarly, this study
the deformation expressed in length, needs to be expanded to various types of permanent
while stress is equal to the force di- waves, such as alkaline permanent waves.
vided by the cross-sectional area of
the fiber. The modulus is usually ob-
Reproduction of all or any part of this article in English or any other
tained in the Hookean region (less language is strictly prohibited.
than 2% strain) where the fiber can be References
stretched repeatedly without under- Address correspondence to Ali N. Syed. c/o Editor. Cosmetics & Toiletries
magazine. 362 South Schmale Road. Carol Stream, IL 60188-2787 USA.
going permanent deformation or dam-
age from extesion. J Menkart, LJ Wolfram and I Mao, Caucasian hair, Negro hair, and wool:
This study needs to be expanded Similarities and differences, J Soc Cosmet Chem 17 769-787 (1966)
2. CE Reese and H Eyring, Mechnical properties and the structure of hair,
to many different hair shades in per- Textile Res J 20743-750 (1950)
3. YK Kamath, SB Hornby and HD Weigman,
Mechanical and fractographic behavior of
Negroid hair, J Soc Cosmet Chem 35 21-43
(1984)
4. R Wickett, Kinetic studies of hair reduction
uSing a single fiber technique, J Soc Cosmet
Acyl Lactylates research Chem 34301-316 (1983)
5. EG Bendit, There is no Hookean region in the
ming, stable, proven, effective as excellent stress-strain curve of keratin, J Macromol Sci-
ulator controlled foaming agents and foam Phys B17(1) 129-140 (1980)
based personal care boosters with adjusted 6. W Edman and M Marti, Properties of peroxide-
bleached hair, J Soc Cosmet Chem 12 133
ts is a reality. ratios of nonionic or ampho- (1961)
Key -- Integrating RITA teric surfactants. 7. L Wolfram, The reactivity of human hair: A
review, in Hair Research, New York: Springer-
The Reuolutionary new RITR Product line -- 8
Verlag (1981) p 497
TA Evans, TN Ventura and AB Wayne, The
5Uersatile Cost Effectiue Ritafactant Blends kinetics of hair reduction, J Soc Cosmet Chem
45 279-298 (1994)
• Easy-to-handle in a blended liquid form - they do not require 9. EI Valko and G Barnett, A study of the swelling
of hair in mixed aqueous solvents, J Soc Cosmet
preheating. Chem 3108-117 (1952)
• Available for clear or opaque blends; torJ;1ll!lat lDJ;S!FJUllY 10 Milady's Standard Text Book of Cosmetology,
Albany, New York: Thomson Learning (2000) p
cold mix and all natural ~urf~ctanri~~tipns.
233
• Choose from various lJlendsf?r spe~iflc pelrfprman(~y 11 M Feughelman, Physical properties of hair, in
characteristics or Ritafactants cifn be tailor-made to cu:stomei('g Hair and Hair Care, DH Johnson, ed, New York:
i;;,,,i Marcel Dekker (1997) P 17
specific applications. 12. NH Chamberlain and JB Speakman, Z
Electrochemie 37 374 (1931)
13 A Shansky, The osmotic behavior of hair during
Ritafactant Blends the permanent waving process as explained by
Are Patent~dbg Milder, Rich swelling measurements, J Soc Cosmet Chem
14427-432 (1963)
the RITA Corporation. 14. J Nothen, V Bollert, G Blankenburg and H
For a FREE Product
Foaming Hocker, The influence of the cosmetic swelling
behavior on the quality of the permanent wave,
Proceedings of the 16th IFSCC Conference,
Sample or more
information, ball:
(800) 426..7759
t It New York, October 8-11, 1990, vol 1 (1990) pp
315-324
15 A Syed, H Ayoub and A Kuhajda, Recent
advances in treating excessively curly hair,
lie
Cosmet Toil 113(9) 47-55 (1998)
In IIIinios: 16 A Syed, A Kuhajda, H Ayoub and K Ahmad,
African-American Hair: Its physical properties
(815) 337-2500 and differences relative to Caucasian hair,
Cosmet Toil 110(10) 39-47 (1995)
17. DH Powers and G Barnett, A study of swelling
f@RITA RITt Corporation
of hair in thioglycolate solutions and its
reswelling, J Soc Cosmet Chem 92-100 (1953)
18. JB Speakman, Mechano-chemlcal methods for
use with animal fibers, J Text Inst 38(2) T 102-
126(1947)
19. A Sookne and M Harris, J Res Natl Bur Stand 19
535(1937) C=&T
P.O. Box 1487
Woodstock, IL 60098
FAX: (815) 337quot;2522
E-mail: cservice@ritacorp.com
Web Site: www.ritacorp.com
64/Cosmetics & ToiletrieSii' magazine www.TheCosmeticSite.com Vol. 117, No. 11/November 2002