Note: Descriptions are shown in the official language in which they were submitted.
~ ~a ~ Y
~ 1 --
BACKGROUND` `OF `THE `INVENTION
The present invention relates to surgical sutures,
and more particularly, to soft, elastomeric sutures having
unique handling and knGt tying characteristics. The sutures
may be prepared from segmented copolyether/esters or other
5 elastomeric polymers.
Many natural and synthetic materials are presently
used as surgical sutures. These materials may be used as
single filament strands, i.e, monofilament sutures, or as
multifilament strands in a braided, twisted or other multi-
ln filament construction. ~atural materials such as silk, cotton,linen and the like, of course do not lend themselves to the
fabrication of monofilament sutures and are accordingly
generally used in one of the multifilament constructions.
Synthetic materials which are extruded in continuous
15 lengths can be used in monorilament form. Common synthetic
monofilament sutures include polyethylene terephthalate,
polypropylene, polyethylene, and nylon. Such monofilament
sutures are preferred by surgeons for many surgical applications
due to their inherent smoothness and noncapillarity to body
20 fluids.
The presently available synthetic monofilament
sutures all sufer to a greater or lesser degree from one
particular disadvantage, that is inherent stiffness. Besides
making the material more difficult to handle and use, suture
25 stiffness can adversely affect knot tying ability and knot
security. It is because of the inherent stiffness of available
monofilament sutures that most larger suture sizes are braided
or have other multifilament constructions with better handling
flexibility.
Monofilament sutures of the prior art are also
characterized by a low degree of elasticity, the most elastic
of the above-mentioned synthetics being nylon which has a
yield elongation of about 1.7 percent and a visco-elastic
elongation of about 8.5 percent. The inelasticity of these
35 sutures also makes knot tying more difficult and reduces knot~~~
'~
lZ~3~3`~
security. In addition, the inelasticity prevents the suture
from "giving" as a newly sutured wound swells, with the result
that the suture may place the wound tissue under greater
tension than is desirable, and may even cause some tearing,
5 cutting or necrosis of the tissue.
The problems associated with the use of inelastic
sutures in certain applications were recognized in U.S. Patent
No. 3,454,011, where it was proposed to fabricate a surgical
suture composed of Spandex* polyurethane. Such sutures,
however, were highly elastic with "rubbery" characteristics
and did not find general acceptance in the medical profession.
It is accordingly an object o~ the present invention
to provide a novel soft, limp, monofilament suture material.
It is a further object of this invention to provide a mono-
filament suture with a controlled degree of elasticity toaccommodate changing wound conditions. It is another object
of this invention to provide a new, nonabsorbable suture having
a diameter of from about 0.01 to 1.0 mm and possessing unique
and desirable physical properties. These and other objects
will be made apparent from the ensuing description and claims.
SUMMARY
Monofilament sutures of the present invention are
characterized by the following combination of physical
properties:
Yield elongation - from about 2 to 9 percent
Visco-elastic
elongation - from about 10 to 30 percent
Young's modulus - preferably from about 30,000
to 320,000 psi
Tensile strength - at least about 40,000 psi
Knot s-trength - at least about 30,000 psi.
Sutures possessin~ the above characteristics may be prepared
by melt extruding certain elastomeric polymers such as
copolyether/ester polymers to form a continuous filamentary
strand, and thereafter drawing the extruded filament to
obtain the desired suture properties. Certain copolyether/
ester polymers available commercially from E.I. du Pont de
*Trade mark
3~37
-- 3 --
Nemours & Co. under the trademark "HYTREL" have been discovered
to be suitable starting materials for the preparation of
sutures in accordance with the present invention.
This invention is therefore further characterized
5 by the use of such polymers which comprise intrapolymerized
butylenephthalate hard segments and polytetramethylene ether
soft segments and having the following general structure
(o - (CH2)4 ~ - Cta (o(cH2cH2cH2cH2o)x C ~ -~
(hard segment) (soft segment)
The monofilament non-absorbable sutures of this invention
are in a sterile condition with a needle attached to at least
one end thereof.
Monofilament sutures having physical properties in
accordance with the present invention are particularly useful
in many surgical procedures where the suture is used to close
a wound which may be subject to later swelling or change in
position. The combination of low Young's modulus and signif-
icant yield elongation provides the suture w.ith an appreciable
degree of controlled elasticity under low applied force. As
a result, the suture is able to "give" to accommodate swelliny
in the wound area. The relatively high visco-elastic yield
elongation and high tensile strength of the suture allows
the suture to stretch during knot tie-down so that the knot
"snugs down" for improved tying ability and knot security
with a more predictable and consistent knot geometry regardless
of variations in suture tying technique or tension.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 is a representive stress-strain curve
characteristic of the surgical filaments of the present
invention.
Figure 2 is a representative stress-strain curve
comparing filaments of the present invention with monofilament
sutures of the prior art.
`` ~ ;Z1~3:~3'7
-- 4 --
DEs(~ o~ OF PR~ ;~K~;L~ EMBO~ IENTS
.
The sutures of the present in~ention are character~
ized by a combination of~ physical properties which are unique
for monofilament sutures, and which provide the sutures of the
5 present invention with unique and desirable functional proper-
ties.
The characteristic propertïes of the inventive
sutures are readily determined by conventional test procedures.
Figure 1 illustrates a typical stress-strain or load-elongation
10 diagram for the sutures of this invention. In Figure 1, yield
elongation (Ey) is the point at which permanent deformation of
the suture begins to ta~e place. So long as the filament is
- not elongated beyond Ey, elastic recovery is essentially complete.
The sutures of the present invention have an Ey with the range
15 of 2 to 9 percent.
Young's modulus is a measure of the slope of the
stress-strain curve over the initial portion of the curve ex-
tending from the origin. In Figure 1, line a is a drawn tangent
to the curve at the origin, and Young's modulus is equal to
20 tan ~. The slope of the curve, and Young's modulus, are seen
to be a measure of the resistance to elongation in the initial
elastic portion of the curve. The sutures of the present
invention are designed to have a significant, but relatively
lo~ modulus of 30,000 to 320,000 psi and preferably 200,000 psi,
25 and more preferably within the range of 50,000 to 150,000 psi.
A modulus within the claimed range provides the correct amount
of increasing tension on the suture as the suture is extended
towards its yield point (Ey). At lower values of Young's modulus
the suture readily elongates under very low tension to its yield
30 point and the advantages of having a significant yield elonga-
tion are lost. At higher values of Young's modulus, filament
stiffness becomes the controlling consideration, and the softness
and good handling properties of the suture ~;m;n;sh
~ The portion of the stress-strain cur~e extending
35 between Ey and Ev on Figure 1 i5 the visco-elastic region during
which there is considerable elongation and permanent deformation
of the suture with only slightly increasing tension. The visco-
3~3~
elastic elongation (E~) o~ the sutures of the present in~ention
is controlled to be within the xange of from about 10 to 30
percent. This property of the suture allows the suture to
draw down during knotting to assure good knot security.
As the suture is elongated beyond Ev, the ioad
increases rapidly as indicated in Figure l. This rapid increase
in load imparts a positive feel to the suture which, in the
hands of a skilled surgeon, signals when Ev and maximum knot
security are achieved. Preferably, the value of Ev is at least
2.5 times the value of Ey in order to provide the surgeon witha broad visco-elastic region in which to work during suture tie-
down.
As seen in Figure l, the load from 0 to Ev elongation
is relatively low compared to the breaking load (Sb). Preferably,
the breaking load or straight tensile strength is at least 40,000
psi, and the load Sv corresponding to visco-elastic elongation
is less than one-third of the breaking load, with the result
that the suture may be easily knotted under relatively low forces
and without risk of unintentionally breaking the suture. Knot
strength of the suture is preferably at least 30,000 psi.
The breaking elongation (Eb~ of the sutures of the
present invention are generally within the range of 30 to 100
percent. ~lthough this property is not critical to the perform-
ance of the suture since suture elongation in use does not
generally exceed Ev, it is preferabIe that Eb be at least 1.5
x Ev in order to reduce the possibility of inadvertantly over
elongating and breaking the suture during tie-down.
The unique mechanical properties of the sutures of
the present invention will be more readily appreciated from
Figure 2 where such sutures are compared to nylon and polypro-
pylene sutures of the prior art. Representative physical
properties of these three suture materials are given in Table I.
Each of these prior art sutures has a considerably higher Young's
modulus which results in the characteristic stiffness of these
materials. In addition, neither suture has a noticeable Ey or
an extended visco-elastic region which characterïze the sutures
of the invention and impart the desirable properties discussed
3L2q33~1L3~
above.
The mechanical properties of the sutures of the
present invention reflected in the relative values of Ev and Ey
in combination with the low Youn~ls moduius and high tensile
5 strength are unique in the field of surgical sutures and dis-
tinguish the monofilament sutures of the present invention
from all prior art material~.
TABLE I
Suture property Suture material
Polypropylene Nylon This
invention
Diameter, mils 12.5 12.8 12.9
(mm~ (0.32~ (0.33) (0.33t
Tensile strength, psi 58,900 75,200 64,700
(Kg/cm2~ ~4,100) (5,300)(4,500)
Elongation to break, ~ 32.2 40.1 39.5
Visco-elastic elongation (E~), % 9.0 8.5 14.8
Yield elongation (Ey), % 1.1 1.7 2.2
S~ress at Ey (Sy), psi 5,100 3,600 2,500 ~ e
(Kg/cm2) (360) (250) (180)
Stress at Ev (Sv), psi 25,700 13,200 9,200
(Kg/cm2) (1,800) (930) (650)
Young's modulus, psi 425,000 221,000112,000
(Kg/cm2) (29,900j (15,500)(7~900)
33~3~9
Sutu.res ha~ing mecha.~ic.a~ properties in accordance
with the present invention.~ay be p~epared from the segmen.ted
copolyether/ester compositions disclosed in U.S. Patent ~o.
3,023,192, which states in part at Column 2, line 20 et seq.:.
"The copolyetheresters of thïs invention
are prepared by rea.cting one or more boxylic
acids or their ester-forming derivatives, one
or more difunctional polyethers with the formula:
HO(RO)pH
(in which R is one or more divalent organic
radicals and p is an integer of a value to
provide a glycol with a molecular weight of
between about 350 and about 6,00Q~, and one
or more dihydroxy-compounds selected from the
class consisting of bis-phenols and lower ali-
phatic glycols with the formula:
HO(CH2)~OH
(in which q is 2-10, with the proviso that the
reactants be selected so that substantially all
of the repeating units of the polyester contain
at least one aromatic ring. The resulting
ester is then polymerized."
The preparation of other related segmented thermo-
plastic copolymers are described in the following additional
references: U.S. Patents Nos. 3,651,014; 3,763,109; 3,766,1~6;
and 3,78~,520.
According to the above references, the disclosed
segmented thermoplastic copolymers may be cast as films,
injection molded to form objects, or melt extruded to form
filaments. The products obtained in accordance with these
references, however, are characterized by physical proper~ies
which are not desirable for surgical sutures.
In particular, the filaments o the references are
rubbery with a very high de~ree o~ elasticity as indicated by
break elongations in excess of 500 percent. Tensïle strengths,
on the other hand, are ~ery low, generally less than 8,000 psi.
The ~ilaments prepared from.copolyether/esters in accordance
'~2~:)3:13~
with the teachings of these referen.ces therefore do not possess
the mechanical properties of the sutures of the invention, and,
in fact, are obviously not at all suitable for use as surgical.
sutures.
The disadvantages of the prior art references are
overcome by means of the present invention wherein filaments
extruded from certain copolyether/esters are quenched and drawn
with the result that the mechanical properties of the filaments
are controlled to be within the specific limits discovered to
be particularly desirable for surgical sutures.
The segmented copolyether/esters useful in the present
invention comprise a multiplicity of recurring long chain ether/
ester units and short chain ester units joined head to tail
through ester linkages according to the following general formula:
O O O O
[(O - D - O - C - R - C)a(O - G - O - C - R - C ~ )b3n (I)
The long chain ether/ester units of the polymer are represented
by the general formula:
O O
,. ..
- O - G - O - C - R - C - (II)
wherein G is a divalent radical remaining after the xemoval of
terminal hydroxyl groups from à poly (C2 10 alkylene oxide)
glycol having a molecular weight within the range of about 350
to 6,000, and R is a divalent radical remaining after the removal
of carboxyl groups from an aromatic dicarboxylic acid having a
molecular weight of less than about 300.
The short chain ester units are represented by the
general formula:
O O
ll ll
- O - D - O - C - R - C - (III)
wherein D is a divalent radical remaining after remoual of
hydroxyl groups from an alkyldiol having a molecular weight of
less than about 250, and R is as defined above.
In the above Formula I, a is an integer such that
the short chain copolymer segments represented by a comprise
from 50 to 90 percent by weight of the total copolymer composi-
3~ 7
- 1.0
tion; _ is an integer such that the long chain copolymer seg-
ments represented by b comprise from 10 to 50 percent of the
total copolymer composition; and n is the degree of polymeriza-
tion resulting in a f:iber-orming copolymer.
The copolyether/esters represented by Formula I may
be melt extruded, quenched and drawn to obtain filaments having
physical properties desirable for surgical sutures as above
defined. Polymer to be extruded is dried at about 200-220F in
a circulating hot air oven and/or under vacuum in order to
remove all traces of moisture and other volatile materials.
The polymer is then melt extruded and water quenched in accor-
dance with the conventional melt spinning techniques forsynthetic fibers. The fiber is finally drawn at least about
5X, and usually ~rom about 7X to 9X to achieve molecular orien-
tation.
The preparation of fibers useful as surgical suturesfrom copolyether/esters in accordance with the present invention
is demonstrated by the following examples which are presented
by way of illustration and are not limiting of the present
invention. The polymers utilized in these examples are copoly-
ether/esters prepared from 1,4-butanediol, dimethyl phthalate,
and polytetramethylene ether glycol (M/W/ of about 1,000), and
are ~ ~L~ially available from E.I. du Pont de Nemours & Co.
under the trademark "HYTREL". The polymer contains intrapo]y-
merized butylenephthalate hard segments (short chain ester units)and polytetramethylene ether terephthalate soft segments (long
chain ester units) and has the following general structure as
reported in the Journal of Elastomers and Plastics 9, 416-38
(Oct., 1977):
O O O O
Il ~ 11 11
30 ( ~ (CH2)4 ~ C ~ ~ ~a ((CH2CH ~ 2cH20)x _ C ~ -C~b (IV)
thard segment) (soft segment)
wherein a and b are as defined above a~d x is an integer
xeflecting the molecular weight of the ethex ~lycol reactant
(x = 14 for M~Wo of about 1,000).
f~L2~3~3'7
In the following exa~les, physical properties of
individual monofilaments were determined on an Instron*
tensile tester under the following conditions~
Crosshead speed (XH)~ 5 in/min
Chart speed (CS) : 10 in/min
Sample length (GL) . 5 in
Scale load (SL) ~ 2 lbs~in
With reference to Figure 1, Young's modulus is
calculated from the slope a of the stress-strain curve in the
initial linear~ elastic region as follows-
, tan ~ x GL x ~'S x SL
Young s modulus ~pSl) = XH x XS
wherein ~ = the angle indicated in Figure 1XS = the cross-sectional area of the fiber, in2
SL, XH, CS, and GL are as identified above.
Yield stress (Sy) is the load at the point of inter-
section of lines a and b drawn tangent to the initial elastic
region and the visco-elastic region, respectively, of the curve
as illustrated in Figure 1. Yield elongation (Ey) is the elong-
ation corresponding to Sy and is read directly off the stress-
strain curve.
Visco~elastic stress (Sv) is the load at the point
of intersection of line b with line c drawn tangent to the
curve as illustrated in Figurè 1. Visco-elastic elongation
(Ev) is the elongation corresponding to Sv and is read directly
off the curve.
~reak elongation ~Eb) and breaking tensile strength
(Sb) are read directly off the stress-strain curve as illus-
trated in Figure 1.
EXAMPLE I
A sample of copolyether/ester of Formula IV having
approximately 40 wt percent soft segments and comprising ap-
proximately 51 percent terephthaloyl units, 16 percent units
derived from polytetramethylene ether glycol, and 33 percent
units derived from 1,4-butanediol was dried four hours at 200F
in a circulating hot air oven and then further dried under vacuum
at 100 microns (no heat) fGr 16 hours. The dry polymer was
placed in a one-inch horizontal extruder and extruded through
*Trade ~ark
~`.33~3~
- 12 -
a J/50/1 die at an extrusion te~pe~ature of 380F.
The extrudate was quenched in water at ambient
temperature and drawn to a si~e 2-0 monofilament suture using
a 8.8X draw ratio at a temperature of 530F and with a take-
up speed of 485 ft/min. Physical properties of the resultingfilaments are given in Table II.
EXAMP~E II
.
A sample of copolyether/ester of Formula IV having
approximately 23 wt percent soft segments and comprising ap-
proximately 45 percent terephthaloyl units~ 4 percent ortho-
phthaloyl units, 20 percent units derived from polytetramethylene
ether glycol and 31 percent units derived from 1,4-butanediol
was dried and extruded at 400F as described in Example I. The
extrudate was quenched and drawn into a size 2-0 monofilament
using a 7.5~ draw ratio at a temperature of 450F and with a
take-up speed of 412 ft/min. Physical properties of the result-
ing filaments are given in Table II.
EXAMPLE III
A sample of copolyether/ester of Formula IV having
approximately 18 wt percent soft segments and comprising ap-
proximately 41 percent terephthaloyl units, 35 percent units
derived from polytetramethylene ether glycol and 24 percent
units derived from l,4-butanediol was dried and extruded at
~05F as described in Example I. The extrudate was quenched
and drawn into a size 2-n monofilament suture using a 6.5 draw
ratio at a temperature of 560F. The take-up speed was 75 ft/min.
Physical properties of the resulting filaments are given in
Table II. It is noted that the Young's modulus of these fila-
ments exceeded the preferred maximum desirable limit for
sutures of the present invention.
EX~PLE IU
Three parts of a copolyether/ester of Example I and
two parts of a copolyether/ester of Exa~ple III were dry blended
to provide a polymer having a total of 30.2 perce~t soft seg-
ments. The blended material was dried in a vacuum o~en fortwo hours at 1-2 mm Hg (no heat~ and then heated at 50C for
three hours at 1-2 mm Hg.
~13~3~7
- 13 -
The dried mixture was me~t blended in a 3/~-inch
Brabe~der extruder with a 25-inch barrel with a 20/1 screw
and extruded at 430F through a 5~32-inch die in a vertical
monofilament assembly. The extrudate was water quenched at
ambient temperature~ pelletized, and again dried as described
above for the dry-blended material before extruding into mono-
filament sutures. A size 2-0 monGfilament suture of this
material was extruded at 400F using a 7.9X draw ratio at a
temperature of 460F and a ~ake-up speed of 435 ft/min.
Physical properties of the resulting filaments are given in
Table II.
EXAMPLE ~
3.5 parts of a copolyether/ester of Example I and
1.5 parts of a copolyether/ester of Example III were dry-blended
for a total of 33.4 percent soft segments and extruded follow-
ing the general procedure of Example IV, and using a final draw
ratio of 7.5X with a draw temperature of 485F and a take-up
speed of 412 ft/min to obtain a size 2-0 monofilament suture.
The physical properties of the resulting filaments are given
in Table II.
EXAMPLE ~I
The procedure of Example IV was repeated using
`various blends of copolyether/ester polymers of Examples I, II
and III having the compositions and blended in ratios as shown
in Table II. The physical properties of the resulting filaments
are also given in Table III.
EXAMPLE VII
A copolyether/ester of Example I with 40 wt percent
soft segments was dried and extruded in accordance with the
general procedure o Example I using a 20 mil spinnerette to
obtain a size 5-0 suture, and a 50 mil spinnerette to obtain-
a size 0 suture. Drawing condition~ and physical properties
of the resulting suture are compared in Table IV with a size
2-0 suture of the same composition prepared according to
Example I.
TABLE II
Examples
I II III IV V
Suture size 2-0 2-0 2-0 2-0 2-0
Diameter, mils 11.1 13.1 12.2 13.2 13.2
~mm) (0.28)(0.33) ~0.31) (0.343 (0.34~
Knot strength, psi 37,20039,700 44,900 40,100 41,000
(Kg/cmZ) (2,600)(2,780)(3,140) (2,800) (2,870)
Tensile strength, psi 64,1bO 71,300 72,300 65,500 60,500
(Kg/cm2) (4 (5,060) (4,580) (4,200)
Break elongation, % -31.8 27.8 18.3 25.2 31.4
Visco-elastic elongation, % 18.6 13.3 7.25 10.35 11.6
Yield elongation, ~ 3.2 2.9 2~6 4.2 4.7
Young's modulus, psi50,000172,000 320,000 140,000 120,000
(Kg/cm2) (3,500)~12,000) (22,400) (9,800) (8,400)
TABLE III
Polymer compositions Wt % Young's Break Visco- Yield
Wt ~ soft Wt ratio soft modulus elonga- elastic elonga-
segments of of segments psi tion elonga tion
components components in blend (Kg/cm2~ Eb, ~ tion Ey, %
Ev, %
40/23 65/35 34.0584,000 34.8 14.3 9.2
( 5,850)
40/18 75/25 34.50107,000 33.4 13.3 3.2
( 7,470)
40/23 50/50 31.50105,000 33.7 14.7 1.9
40/18 70/30 33.40120,000 31.4 11.6 4.7
~ 8,390) ~3
4~/18 65/35 32.30134,000 27.5 12.1 4.6
~ 9,400)
40/18 60/40 31.20140,000 26.5 10.2 4.8
~ 9,790)
40/18 55/45 30.10170,000 24.5 10.8 2.6
(11,920)
40/18/23 30/30/40 26.60173,000 18.9 10.3 3.5
(12,080)
40/23/18 3~/30/40 26.10201,000 22.4 10.3 2.8
~14,060)
~(33~
~ 16 -
~T~BLE~IV~`
Suture size
5-0 2-0 0
Draw ratio 7.5 8.8 7~3*
Draw temperature, F 340 530 370
~5 Take-up ft/min 205 485 110
Diameter, mils 7.08 11.10 14.03
Knot strength, psi48,600 37,200 34,200
(Kg/cm2) (3,400) (2,600) (2,400)
Tensile strength, psi67,50064,10068,600
(Kg/cm2) (4,700) (4,400) (4,800)
Break elongation, ~ 43.5 31.8 36.7
Visco-elastic elongation, ~ 10.8 18.6 17.6
Yield elongation, ~ 3.0 3.2 6.3
Young's modulus, psi49,00050,000 51,000
(Kg/cm2) (3,400) (3,500) (3,600)
*Two stage draw
EXAMPLE VIII
Monofilament sutures prepared from a copolyether/
ester of Example II with 23 wt percent soft segments were
sterilized by cobalt-60 irradiation and with ethylene oxide
in accordance with conventional procedures for sterilizing
20 surgical sutures. The physical properties of th~ sutures
were affected only slightly by ethylene oxide sterilization,
and even less by cobalt-60, as shown by the data in Table V.
3.~
- 17 -
TABLE V
5uture Nonsterile Sterilized
control 60
Co E.O.
Diameter, mils 12.5 12.6 13.2
Knot strength, psi35,30033,400 29,900
(Kg/cm2) (2,500) (2,300~ ~2,100)
Tensile strength, psi 70,300 70,000 67,700
(Kg/cm2) (4,900~ (~,900)`(4,800)
Break elongation, %28.2 31.6 45.2
Visco-elastic elongation, %13.2 15.0 23.5
Yield elongation, %2.9 2.3 2.2
Young's modulus, psi185,000165,000138,000
(Kg/cm2) (13,000) (11,600) (9,600)
The important physical properties of the sutures
prepared from copolyether/esters are responsive to changes
in polymer composition and processing conditions. For example,
visco-elastic elongation and yield elongation increase as the
proportion of soft segments in polymer are increased, and
conversely, Young's modulus decreases with an increasing propor-
tion of soft segments. The break elongation may be decreased and
tensile strength increased by employing higher draw ratios during
the manufacture of the suture. By regulation of the composition
and processing variables therefor, it is possible to obtain
specific mechanical properties for individual sutures with a
great degree of latitudeO
While the preceding examples have been directed to
the preparation of monofilament sutures of copolyether/esters,
this was for the sake of convenience in describing one polym~r
system and the effect of various polymer compositions and spinning
condition~ on fiber properties. The copolyether/ester polymers
30 may also be used in the manufacture of braided or other multi-
filament suture constructions, and sinyle filaments and braids
may be used in the preparation of surgical fabrics and knitted
~3~
- 18 -
or woven prosthetic devices such as ~ein and arterial grafts.
In addition, elastomeric filaments having a ~ombination of
physical properties in accordance with the present invention
may be prepared from other polymer systems such as polyurethane
5 or silicone elastomers or polyether copolymers of urethane or
silicone elastomers. ~urthermore, elastomeric filaments of the
present invention may be blended with each other, with other
elastomeric or non-elastomeric filaments, and with either
absorbable or non-absorbable filaments in order to provide
10 yarns and fabrics with special properties, all of which is
deemed to be included within the scope of the present invention.
