Wool WERNER VON BERGEN Forstmann Woolen Co., Passaic, N . J.
001 fabrics have enjoyed their long years of deserved HE; wool outlook in the for wool in the apparel grOUpb popularity because of their comfort, good wear, and excelA very interesting analysic battle of fibers is problent appearance. These are the properties that make the ably best summarized in (19) was made by the D u use of wool important and necessary, especially for outerPont Co. for the year 1949. the pamphlet ( 8 ) entitled, wear garments. These functional properties are due to Extracting from the variouc “The Wool Outlook,’’ pubits peculiar physical and chemical structure. The main tables covering the men’s, lished by the Department attributes of wool are its high moisture absorption, high boys’, women’s, misses’, chilof Commerce and Agriculresilience in its dry and wet state, resistance to wicking dren’s, and infant’s apparel ture of the Commonwealth of water, its ability to felt, its good dyeability, and its groups, we find that wool'^ of Australia in October 1951. resistance to free flaming. I t is the combination of all h good indication of trends main domain is still the these properties that makes wool so outstanding, versatile, heavier outerwear garmenb in the world’s fiber consump and healthful. No other natural or synthetic fiber has such as men’s suitings, top tion can be gained from a yet been found or produced with such qualities. coatings, and overcoatings; &udy of the consumption of the five fibers-cotton, woven and knitted women’e suits, jackets, and coats; and wool, rayon, other synthetics, and s i l k - o v e r the past 30 children’s and infants’ coat9 years in the United States. and coat and legging sets. Table I shows this recent trend in American mills. The wool Table I1 shows the end use changes that took place in these apconsumption figure excludes reclaimed wool and shoddy. The parel groups between the years of 1937 and 1949. Whereas the percentage share of consumption for wool fluctuated the least in total poundage of the various items increased 16% from 311,000,this past 30 years, and its position has held closely around a 9% 000 t o 361,000,000, i t is surprising t o see t h a t the actual perlevel. Unfortunately, the world wool production showed a slight centage of wool products increased 24% from 204,000,000 pounds decline in its percentage share on the world production of all the t o 253,000,000 pounds. Taking the over-all poundage, the inmain fibers combined. From a 19%level in 1900, it dropped t o crease is 31%. t3T0 in 1950. Even so, the actual production increased from I n studying the various itpms, the strongest position wool 1.61 billion pounds to 2.4 billion pounds of clean wool. holds is in men’s overcoats and topcoats and in ladies’ I n order t o get the proper conception of the position wool holds coatings; 95% of the items made are classified as wool items. Between 80 and 90% of the men’s suitings and children’s and in the fiber field, it is necessary to study the traditional end uses
T
-
-
-
-
I
-
-
~llil~llll~lll~~lll~~~~l~~~lil~
September 1952
INDUSTRIAL AND ENGINEERING CHEMISTRY
2157
Table I. -
Year 1920 1930 1938 1946 1947 1948 1949 1950
Cotton 2828.1 2610.9 2918.7 4803.3 4668.1 4461.2 3838.2 4719.8
Consumption of Five Fibers in the United States (2)
Weight of Fibers Consumed (ThouslLb.) Wool Synthetics (clean) Rayon Other Silk 314.2 29.2 8.7 118.8 263.2 75.7 329.3 284.5 51.7 56:O 875.5 6.5 748.1 50.0 987.9 2.0 708.3 1149.5 7.4 75.0 704.5 992.1 92.0 4.4 511.0 145.0 1351.4 636.5 8.4
Total 3180.2 3068.6 3584.3 6489.4 6416.3 6397.7 5437.7 6861.1
Cotton 88.9 85.0 81.4 74.0 72.8 69.7 70.6 68.8
Per Cent of Total synthetics Wool Rayon Other 9.9 0.3 3 9 8.6 9.2 7.9 11.5 13.5 0.9 11.0 15.4 0.8 11.0 18.0 1.2 9.4 18.2 1.7 19.7 9.3 2.1
~~
Bilk 0.9 2.5 1.5 0.1
...
0.1
0.1 0.1
Table 11. Fiber Content Changes in Outerwear Apparel (Millions of pounds) 1937 ManCotton made
Total
Wool
175 32
103 31
36 55
15 47
13 311
8
4
Total Percentage
LOO
65
27
Men’s and boys’ apparel Suits coats, trousers Over;?oatea n d topcoats Women’s a n d misses’ a parel Suits, jackets, a n d s i i r t s (woven) and suits. jackets, a n d skirts (knit) Coatings Children’s and infants’ apparel Coats and coat and legging b e t s
Q
Total
\Tool
..
154 23
103
9 3
87 73
39
24
20
11
61 1
‘I
1949
.-__
1
22
69
361253
24 8
100
70
Cotton
Manmade
9
.
42 1
9 1
39 3
.
3
E 6
I
86” 24
75% staple.
infanta’ coats are made of wool. Of the women’s and misses’ suits, jackets, and skirts, 45% are classified as wool items. The question here is, what are the properties that make the use of wool so important and necessary in these outerwear garments? It ia clear by the name of the items that they are bought for warmth and protective purposes. They have comfort, good appearance, good wear under all conditions, pleasing and fast colors, and style and me known for ease of tailoring.
There is no question that all theEe properties are highly defiirabh also for civilian goods. 111 order to fully understand these properties it is necewtrg. to have a knowledge of the basic physical and chemical structure of the wool fiber. HISTOLOGY OF WOOL FIBER
Because n’ool fiber is the hair of the sheep, by its nature it forniv the protective covering of the animal. The ultimate phgsicnl limit of N O O ~ fibers is a series of minute cells of different forms artd properties, and the cross section reveals that there are either tvc-o er three layers of these cells. These layers are named according to their position-i.e., the cuticle or outerlayer, the cortex or cortical layers, and the medulla (Figure 1). The cuticle is made up of flat, irregular, horny cells or scales. They may overlap like t h e shingles of a roof or fit together like a network of tile6
SINGLE SCALE
CROSS -SECTION
A- CUTICLE 8- CORTICLE CELLS C- MEDULLA
Figure 1 .
Physical Structure of Wool Fiber
Kennedy ( I d ) in one of his recent speeches on why the military will continue the use of wool stated that there are a t least four properties of wool that contribute to its desirability from a military standpoint: 1. Resistance to w-icking of water 2. High resilience when wet 3. Absorptive properties 4. Resistance to free flaming No other fiber developed t o date combines all of these properties in the same way aa does wool. To these four properties may be added the wool fiber’a ability to felt and its good dyeability. 2158
I- EPICUTICLE: 2- EXOCUTICLE 3-ENDOCUTICLE
Figure 2.
Cuticle Structure of Wool (14)
The free end of the scale projects outward and points toward rhe tip of the hair causing the surface of the fiber to present a serrated appearance. Depending on the diameter of the fiber, the number of scalcti necessary t o cover the circumference of the fiber varies consider-
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol, 44, No. 9
ably. The average height of the scales is approximately 28 microns and the average width approximately 36 microns. The thickness varies between 0.5 and 1 micron. This peculiar scale structure is one of the reasons why wool fibers felt. The cuticle as revealed by the optical microscope was regarded until recently simply as a sheath of flattened, overlapping cells cloYely covering the cortex. Recent studies of the cuticle with ulc electron microscope have led to the view that it is an elaborate w -
CO
-c?;"
\
/CHNH )NH )GO co CH-CHz-S-S-CH2-CH NH / )NH co CYSTINE LINKAGE Go -CH )CH\ NH
'
>
FIBRIL
N~CLEUS
/ /
\
,NH
/
Fine Structure of Cortical Cell (14)
)NH
September 1952
)CH NH
\
NH
-+
GO structure of several more or less distinct layers. Lindberg, Mercer, Philip, and Gralen (14, 17) postulated that the cuticle cell consists of three layers. One of the layers, called the epicuticle, appears as a thin, uniformly thick film of about 100 A. Its most remarkable property is its chemical stability (Figure 2). Further research is being conducted to examine these conjectures. The cortical layer, found below the protective cuticle, constitutes the principal body of the wool fiber. It is made up of long, slightly flattened and more or less twisted, spindle-shaped cells. The average cells range from 80 t o 110 microns in length, 2 to 5 microns in width, and 1.2 to 2.6 microns in thickness. Near the center of each cell is a nucleus which has a granular structure (9). Each individual cortical cell again consists of many fibrils and microfibrils. The latter ieem to be formed from a string of globular particles. The forces holding these cells together are not yet fully known. All indications are that they adhere to each other by reason of a cement material between them (Figure 3). The photomicrograph, Figure 4, shows the arrangement of the cortical cells after treatFigure 4. Wool Fiber Showing Arrangement of Cortical Cells ment with solution (X500) after Treatment with of pepsin. Pepsin In medium Treatment: 64 days, 1/10 pepsin, pH 1.8, and coarse wools, 200 c. a third layer is found within the cortical layer-a cellular marrow or medulla. I n the fine merino wools medullated fibers are present to the extent of 1 in 2000. The medulla is built up of many superimposed cells of various shapes, often polygonal, forming a honeycomblike structure. Tiit. fineness or diameter of the fiber ranges between 10 to 70
\
C
/Go -CH Figure 3.
\
-CHe.CH2-COO GLUTAMIC ACID
>GO
-CH )NH
GO
>co
NH3CHtCH2CtQ-CHe-CH LYSINE )NH GO / \ CHNH
\ - NH~-C-NH-CH~-CH~-CHP+ P O CH
11 )" iCH
Dl :\ : ; : : :s;
"
ARGININE
SALT LINKAGES
Figure 5.
Structural Formula for Wool ( I )
microns. The eight grades generally used for outerwear fabrics range from an average of 18 microns for the finest wool (So's) t o 30 microns (50's) which is equal to a denier range from 3 to 9. CHEMICAL STRUCTURE
Our knowledge of the actual chemical structure of the wool protein, known as keratin, is still very limited (10). The main chemical differences between keratin and other proteins is the presence of cystine. Astbury ( 1 ) and Speakman (23)suggest that the structure of the wool fiber reduced to its simplest terms consists of long peptide chains bridged by cystine and salt linkages. Such a structural arrangement accounts for much of the chemical stability of the wool molecules which make up the fiber (Figure 5). The shape of the wool fiber and its ability to recover after deformation is determined by the nature of the bonds holding together the peptide chains and the partially stable patterns. Cystine is important in influencing the behavior of the wool because of its cross linkage-pairs of sulfur atoms held together by mutual attraction. This bond between the two sulfur atoms can be broken or modified with relative ease as compared with the much stronger bonds between the amino acids in the polypeptide chains. The polypeptide chains possess a large number of highly polar linkages which give rise t o inter- and intramolecular hydrogen bonding. These hydrogen bonds are not entirely stable and rigid. There are also certain electrical forces holding the chains together. These are called van der Waals forces and are even weaker. Lundgren (16) visualizes these hydrogen bondings diagrammatically as illustrated in Figure 6.
INDUSTRIAL A N D E N G I N E E R I N G C H E M I S T R Y
2159
The polypeptide chains also contain relatively large side chains, which prevent close packing of the protein molecules and thus decree the extent t o which hydrogen bonding can occur. The polypeptide chains are folded back on themselves. As the fiber stretches some of the folds of the peptide chains are straightened and there is slippage between chains.
Equal elongations can be obtmied iri bynthetics, but thc resulting elastic recovery properties are usultllv pool-that ifi if the fibers can be strained t o such high values, the strain is not recoverable on load removal. Nylon is a n euception, and t h k accounts for its general excellence. The high elongation in wool automatically means that iii rupturing, it is capable of absorbing a large amount of energy Figure 8 shows the normal stress-strain curve of a wool fiber a. established by Wakelin and his associates (26>27) a t the Textilr Research Institute. Table I11 shoas the stress-strain plopelties of foul wooltwhich formed the basic material in a recent inteinational qtrid? on wool by the Textile Research Institute ( 2 5 ) .
P
EL4STIC BEHAVIOR
MODEL CHAIN NETWORK
“ t S j #
A
F 0ace Figure 6.
Diagram Showing Hydrogenation Boridings in Wool Structure (15)
Woo1 is viscoelastic. This is very clearly brought o u t 1x1 Kasmell’s literature survey (11). When a mass of wool fiberc is crumpled and compressed in the hand, it springs back t o itc original shape when released. Therefore wool is accepted a b being soft, springy, and resilient. Time is an important factor in these spring-back, Wool has the reputation of returning extremely quickly. Recent studies have shown that this reputation is well deserved. According t o Hamburger ( 6 ) , aool has an elastic performance coefficiency close t o one. Tests made on a 300-denier worsted yarn produced the following values: after 25% stress, 0.88; after 50% stress, 0.86; and after 90% stress, 0.67, which indicates the excellent recovery that wool a8sumes even with as high as 90% of rupture. Further data on the elastic properties of single wool fibers were presented b> Dillon ( 4 ) . They showed that when cycling at 10% stress, wimi is outstanding in its lorn progression. Recent research of several investigators including Hamburger and coworkers ( 7 )and Gagliardi and coworkers ( 5 )has shown that the strain developed in an apparel fabric is in the low magnitude of 5%* From such deformations wool is able to recover nearlj instantaneously, which is an outstanding characteristic wher, compared with other fibers. Figure 9 shows plots of instantaneous elastic deflection versus the total deflection of wool, hair fibers, silk, acetate, viscose, nylon, Dacron, and Orlon. Perfect elastic material is depicted by the straight line wherein the instantaneous elastic deflection (1.E-D.) equals the total deflection at each point The curve shows clearly that rip tc.
We presume that this deformation is the result of overcoming the van der Waals forces, breaking of the hydrogen bonds, and modification of the disulfide linkages. If the tension is immediately removed this force causes the fiber to return to its original form at once. If the fiber is held under tension 01- stretched beyond its elastic limits, new bonds may be formed in a new position to replace the broken bonds. The polypeptide chain in its normal unstretched or folded form is called a-keratin. There is a n intramolecular transformation from the a-keratin to the @-keratinas the chain molecules unfold (Figure 7 ) . It is obvious t h a t the various molecular arrangements in the structure have a direct Table 111. Stress-Strain Properties of Four Wools (26) influence on the way the fiber stretches and New Zealand Dornaatii. Australian Domestic recovers from stretch. I t is this molecular patFine Fine Medium Medium tern that is responsible for the excellent elastic Denier 3.4 4.2 6.6 6.1 behavior of the wool fiber. The patterns t h a t Diameter, microns 19.2 21.4 26.7 25.7 Standard deviation 2 . 7 2 . 6 4 . 2 3 .1 control deformation also have direct influence Fibers 888 240 432 a44 on t h e softness of wool t o the hand, on the Breaking extensiono, % ability of a woolen garment t o adjust itself Median 33.Y 36.0 35 8 36. I Mean 32.7 32.8 33.6 33.9 to the curves of the body, on its crush resistStandard deviation 8.0 9.6 9.2 9.n Fibers 143 283 240 432 ance and warmth, and on t h e relaxation factors Elastic modulus, g . / as well as the set of the wool fibers, denier 24. p 29.9 2b.4 26.2 Strength is often taken as the main criteria 5.3 4.2 Standard deviation 4.4 3. < 239 132 288 141 Fibers of a fiber. From this angle vi001 would not Stress at 20% occupy the dominant position which it holds, Extension, g./denier 0.89 0.90 1.02 0.028 Standard deviation 0.050 0 0477 0 071 0,061 for its tenacity is only in the neighborhood Fibers 132 255 215 899 of 1.2 t o 1.4 grams per denier, which is a Energy t o 20% low strength compared with values of 6 t o 8 Extension, &./denier 0.143 0.148 0.166 0.152 Standard deviation 0.010 0,0088 0.0145 0.017 grams per denier for nylon. Therefore me know Fibers I32 25.5 214 399 that wool’s attributes are not based on high Breaking stress, g./ strength. 1.23 1.17 1 32 denier 1.14 0.255 0.221 Standard deviation 0.187 0 204 The elongation t o rupture of wool both 240 132 Fibers 143 288 5 dry and wet is in t h e range from 30 t o 50%. Breaking extension has a badly skewed distribution. This is higher than any other natural fiber. ~~
2160
~
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
Vol. 44, No. 9
UNSTRETCHED
SID_E,CHAIN
chemical treatments. Moisture Regain. Wool has a higher moisture regain than any other fiber, being approached MAIN CHAIN only by viscose rayon. Figure 12 shows the absorption and desorption curve of wool as established by Speakman and Cooper ($4) at varioue KERATIN relative humidities. Wool is a hydrophilic fiber and has a higher moisture regain than any other fiber, yet in one way this is a paradox, because wool cannot be used t o mop up a wet floor. I n this respect wool would be hydrophobic, but it is very hygroscopic in respect t o picking up moisture in vapor form. Meredith (18) shows that the heat evolved when a fiber absorbs water is linearly related to its moisture regain, Wool evolves approxiI fl KERATIN mately three times as much heat as does a hydrophobic fiber, such as nylon, when the relaFigure 7. Molecular Chain Pattern Showing Transformation of tive humidity is raised from 0 t o 65. This is a-Keratin to &Keratin on Stretching (10) illustrated in Figure 13 which shows t h a t t h e heat absorption of wool from 0 t o 65 is over three tiTes that of nylon, over- twice that of cotton, and appreciTable IV. Dry and Wet Properties of Woo1 ably more than silk, Fortisan, and mercerized cotton. T h e only fiber that approaches wool is Tonasco (viscose rayon). Grams per Denier Dry Wet Meredith (18) states t h a t in passing from a room at 70" F. and 45% relative humidity into an outside atmosphere of 1.25 1.05 Breaking tenacity 35.7 48.3 Breaking elongation, % about 40' F., 95% relative humidity, a man's jacket weighing 2 Elasticity (Young's modulus) 25.3 12.2 pounds will produce 100,000 calories of heat, or as much heat aB Stress/tenacity at 20% 0.94 0.42 normal body metabolism will produce in 1 hour. This meane t h a t the adjustment a person must make in going from a warm room into the outside cold should be less severe if he wears wool strains of 5%, wool and silk have a greater amouat of perfect than if he wears hydrophobic fibers of extremely low or zero reelasticity than the other fibers shown. gain. MAIN CHAIN
a
THERMAL QUALITLES OF WOOL MECHANICAL PROPERTIES OF WET WOOL FIBERS
Schiefer and coworkers ( b l ) , Rees (20),and M u s h (16) have One of the outstanding advantages of wool is t h a t it has shown that thermal conductivity of a fabric is a direct function of greater ability t o recover from deformation when wet than when its thickness. Therefore, the ability of a fabric t o maintain it@ thickness will control the continued ability of t h e fabric t o he n hY. In Figure 10 are shown the stress-strain curves of medium domestic wool in its dry and wet state (27). Table IV gives the data from these two curves. Of high significance were the findings of Speakman ( 2 2 ) 1.8 which showed that the absorption of water pro1.6 duces little change in wool's initial resistance t o BREAKIN@ STRCSS deformation. This means t h a t the wet wool fabric 1.4 is no more subject to deformation resulting from el s 1.2 small forces than is a dry fabric. u,v) When the dry wool is loaded beyond its yield " 1.0 point, approximately 20% extension, it does not a 0.8 fully recover but is permanently set. The wet fiber, under the same condition, is more easily extended 06 but is 100% recoverable. Figure 11 from Harris a & 0.4 and Brown (8) confirms these findings. In practical use this means that when wool fabrics are ex0.2 posed to high humidities or become wet, they are 0 more distortable, but on removal of stress they 0 5 IO 19 20 25 EXTENSION PERCENT will rework t o their original shape. This reaction explains why t h e wearer of a wool suit on a Figure 8. Typical Stress-Strain Curve for a Wool Fiber (25) humid day may induce many wrinkles in it, when 70' F., 65% R.H. he sits down or crosses his legs, but when he stands uw and moves about. or even better if he takes the suit off and hangs'it up, most of t h e wrinkles will good insulator. The wool fiber lends itself excellently to the hang out. composition of lofty, low density structures. Such fabrics having The excellent elastic recovery properties of wool, both when l u g e thicknesses per weight are therefore good insulators. The dry and wet, particularly at low loads, resulting in its good reexcellent compressional resilience of wool structure, because of t h e sistance t o wrinkling and creasing, has placed t h e use of wool as a good dry and wet elastic recovery properties ensures maintenance
E
September 1952
INDUSTRIAL AND ENGINEERING CHEMISTRY
2161
of the fabric's original thickness and therefore the fabric maintains all the original high thermal insulation per unit weight. Fundamentally, thermal insulation is controlled by the ability of the textile structure to entrap air. Cmsie ( 3 )claims that wool is unique in ability t o keep a high amount of air entrapped because the air clings t o the fibers forming a windbreak. Therefore wool fabrics tend to maintain a high total fiber surface, high thickness, low density, and concomitant air drag and high heat insulation. /DACRON
I 2.0
I T O I LINE
t
MOHAIR
1.5
ACETATE
H
ORLON
a
VlSCOSE
I
I
0
Figure 9.
I
PROCESSABILITY OF WOOL
I
I
5
2 3 4 PERCENT ELONGATION
I
an uncomfortable feeling on the wearer. A fmther advantage of wool, which makes it highly desirable from a body comfort angle, is the rate of gain or loss of its moisture. As already stated, wool has the highest heat of evolution on wetting, and hence it can act as a heat reservoir. The rate a t which vapor can be absorbed or released has a bearing on the heat absorbed or evolved, which in turn affects the skin temperature and comfort of a person. A very rapid evaporation of water can cause serious reduction in skin temperatures in producing a chilling effect. Wool fabrics not only absorb water vapors slowly but also release water at a very low rate. Thus on both absorption and desorption the hydrophilic wool fiber acts as a damping mechanism in protecting the body from sudden environmental changes. Thermal Stability. Wool is a nonthermoplastic fiber; this is of appreciable advantage in terms of ironing and pressing. Thc safe ironing temperature for wool is 375" t o 450" F. Since it i j nonthermoplastic, there is no danger of its melting or heat shrinking excessively. Related t o the high heat stability and the lack of tendency of wool t o fuse is its resistance to flammability, one of the points mentioned by Kennedy (Zd). It is not subject to spontaneous combustion and by and large can be considered one of the safest materials.
Instantaneous. Elastic Deflection ]Deflection of Fibers (7)
VS.
Wool fabrics feel warm t o the touch. This is due to the rough surface most wool fabrics have. Smooth fabrics as well as smooth fibers feel cold and clammy. The explanation is t h a t smooth fabrics will give better heat tmnsfer from skin to fabric thus causing a cool sensation to the skin as heat is given up, whereas wool fabrics which are made from natural crimped fibers have a low emissivity and therefore feel warm. Based on the conductivity and emissivity as well as the heat of moisture absorption, it can be concluded that fabrics made from wool should provide excellent warmth for apparel use, which substantiates the popular conception. Wool fabrics are also outstanding in regard to moisture transfer, especially in the matter of perspiration from the body to the outside. As wool is a hydrophilic fiber, water vapor will pass not only through the fabric interstices, but also through the fibers themselves. Therefore even the wearer of a tightly woven wool fabric mill be comfortable.
Dyeability. -4s wool is sufficiently hydrophilic, it can swell and thus easily be dyed by various classes of dyestuffs. With few exceptions practically any color combination of fastness properties may be obtained. Because of its amphoteric nature acid, chrome, metalized, basic direct, and vat colors can be applied.
PERCENT ELONGATION
Figure 11. Cyclical Loading and Unloading Diagram for Wool Fiber Tested Dry and Wet ( 8 )
0
Figure 10.
I
0
I 1 20 30 PERCENT ELONGATION
I
I
40
50
Stress-Straiii Curves of Medium Wool ( 2 5 ) Dry and wet, 70° F.
Wool dso has the ability to hold more water than other fibers without feeling wet. This fact is responsible for the high resistance to wicking as mentioned earlier. The fiber can absorb Iwge amounts of water before free water appears and produces 2162
Felting. Wool and related animal fibers are the only ones which will felt in the accepted commercial and practical sense. This is one of its most important properties as it makes possible conversion into nonwoven felts, flannels, and the host of woolen and worsted fabrics such as suitings, coatings, and overcoatings. The fulling of the gray goods produces an increase in weight, weight density, and thickness, and the reduction in dimension. To make felting possible, a fiber must possess a surface scale structure; it must be easily stretched and deformed; and it must possess a power of recovery from deformation. Referring to the previous discussion on the scale structure of the fiber and its other elastic properties, wool is unique in its ability to satisfy these three requirements. This ability to felt works to the disadvantage of wool products when they must be wet-laundered, but it can be overcome by the use of chemical treatments which reduces the differential frictional effect.
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 44, No. 9
been made for many of these fibers. I n a talk before the Wool Stock Institute on March 18, 1952, Kruegel (IS) reiterated Kennedy’s statement that as long as no other fiber developed combines all properties of wool in the same way as does wool, there is little probability of wool being replaced in toto as a major military fiber. H e stated further t h a t there is a great deal of evidence that wool has some very desirable properties for use in military textiles. However, the wool textile industry has not, up to this time, studied the functional properties of wool to a sufficient extent for it to be possible to obtain a clear statement of the physical properties of wool which make it a desirable fiber. CONCLUSION
0
IO
20
40 50 60 70 80 RELATIVE HUMIDITY PERCENT
30
90
100
Figure 12. Absorption and Desorption Curve for
Wool (24)
Fabric Hand and Drape. Wool’s low tensional and bending modulus, its high elastic recovery, and excellent compressional resilience accounts for the soft, lofty, flexible characteristics of woolen goods such rn sweaters, blankets, and other woolen and worsted fabrics. RELATION OF WOOL TO SYNTHETICS
There is no question that in the past 2 years the blending of wool with the various synthetics has gained considerable momentum. One of the main impulses is due t o the change of specifications of military fabrics allowing the admixture of 10 to 1f170 of synthetic fibers in fabrics which for centuries have been made with 100% wool. Again referring to the article in “Wool Outlook” ( d ) , it is stated that if in this present period when fiber
The purpose of this paper is to present the current status of research on the physical and chemical properties of the wool fiber which are responsible for the position wool holds in the fiber field. These properties are: the high moisture absorption, the high resilience of wool in ita dry and wet state, the resistance to wicking of water, its ability t o felt, its good dyeability, and its resistance to free flaming. From these facts it is apparent t h a t no fiber has yet acquired the all-around qualities and versatility t h a t wool possesses, especially for its use in outerwear garments. ACKNOWLEDGMENT
The author wishes t o thank The Wool Bureau, especially
G. E. Hopkins, for supplying the literature entitled “Wool--8 Literature Survey of Its Properties and I t s Relative Position in the Field of Textile Fibers,” by E. Kaswell of Fabric Research Laboratories, Inc., and E. Kaswell, particularly for his guidance to the most important references for this work. LITERATURE CITED (1) Astbury, W. T., J . SOC.Dyers Colourists, Jubilee Issue, p. 24 (1934); J . Textile I w t . , 27, P282-97 (1936). (2) Bureau of Agricultural Economics, Dept. of Commerce and
Agriculture, Canberra, Australia, “Wool Outlook” (October 1951).
(3) (4) (5) (6) (7) (8) (9)
Cassie, A. B. D., J. Textale Inst., 37, 556 (1946). Dillon, J. H., IND. ENQ.CHEM.,44, 2115 (1952). Gagliardi, D. D., Textile Research J . , 20, 180 (1950). Hamburger, W. J.. Zbicl., 18, 102 (1948). Hamburger, W. J., et al., Zbid., to be published. Harris, M., and Brown, A. E., Ibid., 77,323 (1947). Hock, C. W., Ramsay, R. G., and Harris, M., J . Research ,Vat2 Bur. Standards,27,181 (1941).
(IO) Hopkins, G . , Textile Research J . , 19, 12 (1949). (11) Kaswell, E., to be published, Reinhold Pub. Co. (1952). (12) Kennedy, S., Daily News Record (Oct. 18, 1951). (13) Kmegel, E. O., Ibid. (March 19, 1952). (14) Lindberg, J., Mercer, E. H., Philip, B., and Gralen, N., Ter-
I IO
I
I
15
20
PERCENT MOISTURE REGAIN
Figure 13. Heat of Absorption am. Moisture Regain of Textile Fibers (18)
blending is gaining momentum, synthetics become established in the consumers’ mind as reasonable substitutes for wool garments, then their competitive position will be considerably improved in any future conflict with the natural fiber. We in the woolen industry are well aware of the fact that the main feature of the recent synthetic development is the production of special fibers with qualities that make them more September 1952
tile Research J . , 19, 673 (1949). (15) Lundgren, H., personal correspondence. (16) Marsh, M. C., J . Textile Inst., T245 (1931). (17) Mercer, E. H., Lindberg, J., Philip, B., and Gralen, N., Text& ResearchJ., 19, 678 (1949). (18) Meredith, R., “Fiber Science,” chapter XI1 (edited by Preston), Manchester, England, The Textile Institute, 1949. (19) Rayonorganon, 22, No. 5, Supplement May 1951. (20) Rees, W. H., J . Textilelast., 37, P132 (1946). (21) Schiefer, H. F., J. Research Natl. Bur. Standards, 32, 261 (1944) (22) Speakman, J. B., J . TextileInst., 18, T431 (1927), (23) Ibid., 27, P231-48 (1936). (24) Speakman, J. B., and Cooper, C. A., Zbid., 27, T191-6 (1936). (25) Textile Research Institute, Wool Project, unpublished mate-
rial.
(26) Von Bergen, W., and Wakelin, J. H., Il’extile Research J.,22, 123 (1952). (27) Wakelin, J. H., Textile Research Institute, Wool Project, un-
published material.
RECEIVED for review March 31, 1952.
ACCEPTED July 7, 1962.
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