Note: Descriptions are shown in the official language in which they were submitted.
CA 03002488 2018-04-18
WO 2017/072127
PCT/EP2016/075700
"BIELASTIC FABRIC AND ITS MANUFACTURING PROCESS"
*****
TECHNICAL FIELD
The present invention relates to a bielas tic fabric comprising biopolyamide
yarn and
elastane yarn, having excellent elastic properties and high dimensional
stability, as well
as to a cost-effective, efficient process for obtaining it.
BACKGROUND OF THE RELATED ART
Environmental impact issues related to the textile industry, in particular
water and air
emissions, use of water and energy, are known and of current interest.
lo It is therefore an important goal to be able to produce textiles and
clothing products
which reduce energy consumption and environmental impact, without impairing
the
technical features of the products themselves.
It is thus an object of the present invention to provide a solution to such
problems,
which simultaneously allows excellent qualities and technical performance to
be
obtained.
SUMMARY OF THE INVENTION
Said object is achieved by a bioelas tic fabric as claimed in claim 1.
In another aspect, the present invention relates to a process for obtaining
such a bielastic
fabric.
In a further aspect, the present invention relates to a clothing or furniture
item, at least
partially made of such a bielastic fabric.
DESCRIPTION OF THE DRAWINGS
The features and advantages of the present invention will become more apparent
from
the following detailed description, from the embodiments shown by way of non-
limiting
examples, and from the accompanying drawings, in which:
- Figure 1 shows the pattern of jersey fabric (weave of stocking stitch)
seen from the
knit side on the left and from the purl side on the right;
- Figure 2 shows the bielastic jersey fabric obtained from Example 1;
- Figure 3 shows the pattern of interlock fabric in which the front overlap
of the front
and back stitches is shown: the latter are represented by thinner lines solely
to help
understanding the figure itself, actually being all of the same length and
width;
- Figure 4 shows the pattern of the same interlock fabric in Figure 1 in
which the
CA 03002488 2018-04-18
WO 2017/072127
PCT/EP2016/075700
overlap of the front and back stitches is shown in perspective; and
- Figure 5 shows the bielastic interlock fabric obtained from Example 3.
DETAILED DESCRIPTION OF THE INVENTION
The invention thus relates to a bielastic fabric comprising biopolyamide yarn
and
elastane yarn.
The term "bielastic" means that the fabric is elastic in the warp and weft
directions.
The term "biopolyamide" means a polyamide entirely or partly of plant origin.
Preferably, the biomass from which the biopolyamide for the purposes of the
present
invention originates is the castor seed, referred to as "Ricinus communis".
The
monomers used in the polymerization process are partly or totally derived from
castor
oil.
Biopolyamides exhibit high resistance to chemical agents, in particular to
hydrocarbons,
dimensional stability, relatively low density and good processability.
Preferably, said biopolyamide is biopolyamide 6, biopolyamide 6.6,
biopolyamide 6.10,
biopolyamide 6.12, biopolyamide 11, biopolyamide 12, or a mixture thereof.
More preferably, said biopolyamide is biopolyamide 6.6.
In embodiments, the biopolyamide yam has a count of 10-200 dTex, preferably 20-
150
dTex.
By "elastane" it is meant a synthetic fiber of polyurethane, also known as
Spandex or
Lycra.
At present, polyurethane is typically produced from raw materials. The
reaction takes
place in two steps, in the first step a polyol is placed to react with a
diisocyanate to form
an intermediate referred to as prepolymer, which will later be co-linked with
amines or
glycols. The polyol is characterized in that it has hydroxyl functional groups
(-OH) at
both ends and will form the elastic part of the molecule; it may be a
polyester or a
polyether or a mixture thereof. The diisocyanate, instead, has isocyanate
functional
groups (-NCO) at its ends and will be the rigid part of the polyurethane. The
isocyanate
most used is diphenylmethane diisocyanate ("MDI", 1-isocyanate-4-[(4-
phenylisocyanate)methyl]benzene).
The reaction takes place between -NCO and -OH groups to form the urea bond and
since the molar ratio of isocyanate to polyol is 2:1, the final product will
be a
macrodiisocyanate, that is, the prepolymer will be a macromolecule having -NCO
2
CA 03002488 2018-04-18
WO 2017/072127
PCT/EP2016/075700
groups at the ends.
The chain extension is obtained by adding bifunctional amines (H2NR-NH2) to
the
prepolymer, which by reacting with the -NCO groups form a urethane bond. The
exothermic reaction increases the molecular weight by hundreds of times and
the
viscosity therewith; in order to keep the product manageable, the reaction is
conducted
in a suitable solvent and small amounts of monofunctional amines regulate the
final
length thereof. The most common solvents are dimethylformamide (DMF) and
dimethylacetamide (DMAc).
A suitable elastane yarn for the purposes of the present invention is the yarn
described
in the international patent application W00181443.
In preferred embodiments, said elastane yarn is the reaction product between
(A)
poly(tetramethylene-ether-co-2methyltetramethylene-ether)glycol, (B) a mixture
of 1-
isocyanate-4-[(4'- isocyanatephenypmethyl]benzene (abbreviated "4,4' -MDI")
and 23-
55 mol% of 1-isocyanate-2-[(4'-isocyanatephenyl)methyl]benzene (abbreviated
"2,4'-
MDI") over the total diisocyanate, and (C) at least one chain extender.
More preferably, said elastane yarn is the reaction product between (A)
poly(tetramethylene-ether-co-2methyltetramethylene-ether)glycol, (B) a mixture
of 1-
isocyanate-4-[(4'- isocyanatephenypmethyl]benzene and 28-55 mol% of 1-
isocyanate-
24(4' -isocyanatephenyl)methyl]benzene over the total diisocyanate, and (C) at
least one
chain extender.
Preferably, the chain extender is ethylenediamine, 1,4-butanediamine, 1,6-
hexanediamine, 1,2-propanediamine, 1,3-propanediamine, 2-methy1-1,5-pentane-
diamine, 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, 1,3-diaminopentane,
or a
mixture thereof.
In preferred embodiments, the chain extender is ethylenediamine.
The elastane yarn is preferably obtained by dry spinning.
Preferably, the bielastic fabric comprises at least 60% of biopolyamide yam,
more
preferably at least 70% of biopolyamide yam.
Preferably, the bielastic fabric comprises at least 5% of elastane yarn, more
preferably
at least 15% of elastane yarn.
In embodiments, the elastane yarn has a count of 10-200 dTex, preferably 15-
100 dTex.
Alternatively, commercially available elastane yarns may be used, such as the
Easy Set
3
CA 03002488 2018-04-18
WO 2017/072127
PCT/EP2016/075700
LYCRA yarns marketed by Invista.
Preferably, the bielastic fabric has a basis weight of 50-270 g/sqm
(grams/square meter).
The basis weight is the weight of a fabric per unit area, expressed in grams
per square
meter, and is an indication of the total amount of fiber in the fabric.
Typically, reference
is made to a "nominal basis weight" rounded for practical reasons to tens of
grams,
therefore different from the actual basis weight, which corresponds to the
actual weight
per unit area. For the purposes of the present invention, the basis weight
indicated is a
nominal basis weight, which corresponds to the actual basis weight 5 g/sqm.
The
measurement of the basis weight is obtained by taking a fabric round having a
diameter
of 11 cm and weighed with a precision balance.
In some embodiments, the bielastic fabric comprises at least 60% of
biopolyamide yarn
and at least 5% of elastane yarn.
Preferably, the bielastic fabric comprises at least 70% of biopolyamide yarn
and at least
15% of elastane yarn.
More preferably, the bielastic fabric comprises 75-90% of biopolyamide yarn
and 10-
25% of elastane yarn.
Preferably, the bielastic fabric has jersey stitch or interlock stitch.
"Jersey" is a fabric made of stocking stitch; the name refers to most of the
products of
the knitwear industry. Produced with knitting machines, it is elastic both in
length and
in width and if made in warp, it has ladder-proof properties. An example of
jersey fabric
pattern is shown in Figure 1.
"Interlock" is a crossed knitted fabric; it is a variant of jersey but easier
to cut; it is one
of the fundamental weaving of weft knitting, made on double knit machines,
i.e. with
two series of needles working in opposite positions. The cylinder needles are
coincident
with the dial needles, so they cannot stitch together; so, one yarn is worked
by the odd
needles of the cylinder needles and the even ones by the dial needles, thus
forming a
first row of rib stitch. The subsequent yarn is worked by the needles, which
have not
worked the first one: a second rib row is thus obtained, "crossed" with the
first one.
This results in a thickness and volume similar to those of the rib stitch but
with a much
more reduced extensibility. An example of interlock fabric pattern is shown in
Figures 3
and 4.
In some embodiments, the bielastic fabric has a basis weight of 100-250 g/sqm.
4
CA 03002488 2018-04-18
WO 2017/072127
PCT/EP2016/075700
Preferably, the bielastic fabric has a basis weight of 180-210 g/sqm, more
preferably
190-200 g/sqm.
Preferably, the bielastic fabric has a basis weight of 100-140 g/sqm, more
preferably
110-130 g/sqm.
Preferably, the bielastic fabric has a basis weight of 160-200 g/sqm, more
preferably
170-190 g/sqm.
In some embodiments, the bielastic fabric has 40-200% of elasticity in the
weft.
Preferably, the bielastic fabric has 45-90% of elasticity in the weft, more
preferably 50-
80%.
Preferably, the bielastic fabric has 120-200% of elasticity in the weft, more
preferably
140-180%.
Preferably, the bielastic fabric has 110-190% of elasticity in the weft, more
preferably
130-180%.
In some embodiments, the bielastic fabric has 30-200% of elasticity in the
warp.
Preferably, the bielastic fabric has 35-80% of elasticity in the warp, more
preferably 45-
70%.
Preferably, the bielastic fabric has 120-200% of elasticity in the warp, more
preferably
140-180%.
Preferably, the bielastic fabric has 50-100% of elasticity in the warp, more
preferably
60-90%.
More preferably, the bielastic fabric has a basis weight of 100-250 g/sqm, 40-
200% of
elasticity in the weft and 30-200% of elasticity in the warp.
For the purposes of the present invention, the elasticity is measured by
taking 10x5 cm2
strips of fabric and placing them in a dynamometer (e.g. dynamometer
Zwick/Roell
Z0,5). By "elasticity in the weft" it is meant the measure of the elasticity
taken in the
weft direction, while "elasticity in the warp" means the measure of the
elasticity taken
in the warp direction.
In some embodiments, the bielastic fabric comprises 75-90% of biopolyamide
yarn and
10-25% of elastane yarn, and has jersey stitch, a basis weight of 180-210
g/sqm, 45-
90% of elasticity in the weft and 35-80% of elasticity in the warp.
Preferably, the
bielastic fabric comprises 80-90% of biopolyamide yarn and 10-20% of elastane
yam,
and has jersey stitch, a basis weight of 190-200 g/sqm, 50-80% of elasticity
in the weft
5
CA 03002488 2018-04-18
=
WO 2017/072127
PCT/EP2016/075700
and 45-70% of elasticity in the warp.
In other embodiments, the bielastic fabric comprises 75-90% of biopolyamide
yarn and
10-25% of elastane yarn, and has jersey stitch, a basis weight of 100-140
g/sqm, 120-
200% of elasticity in the weft and 120-200% of elasticity in the warp.
Preferably, the
bielastic fabric comprises 70-80% of biopolyamide yarn and 20-30% of elastane
yarn,
and has jersey stitch, a basis weight of 110-130 g/sqm, 140-180% of elasticity
in the
weft and 140-180% of elasticity in the warp.
In further embodiments, the bielastic fabric comprises 75-90% of biopolyamide
yarn
and 10-25% of elastane yarn, and has interlock stitch, a basis weight of 160-
200 g/sqm,
110-190% of elasticity in the weft and 50-100% of elasticity in the warp.
Preferably, the
bielastic fabric comprises 70-80% of biopolyamide yarn and 20-30% of elastane
yam,
and has interlock stitch, a basis weight of 170-190 g/sqm, 130-180% of
elasticity in the
weft and 60-90% of elasticity in the warp.
Optionally, the bielastic fabric may further comprise at least one yam of
natural fiber
selected from wool, cotton, silk, and flax.
Optionally, the bielastic fabric may further comprise at least one yam of
synthetic fiber
selected from polyester, polyamide, acetate, acrylic, rayon, and polyolefin,
such as
polyethylene or polypropylene.
In some embodiments, the bielastic fabric consists essentially of biopolyamide
yarn and
elastane yarn. The expression "essentially consists of' indicates that the
fabric may
further comprise other types of yarns which, however, do not alter the
technical features
of the final bielastic fabric.
In further embodiments, the bielastic fabric consists of biopolyamide yarn and
elastane
yarn.
It is to be understood that all aspects identified as preferred and
advantageous for the
bielastic fabric comprising biopolyamide yarn and elastane yarn are to be
considered
similarly preferred and advantageous also for the bielastic fabric essentially
consisting
of biopolyamide yam and elastane yarn, and for the bioelastic fabric
consisting of
biopolyamide yam and elastane yarn.
In another aspect, the present invention relates to a manufacturing process of
the
bielastic fabric as described above, said process comprising the steps of:
a) stitching biopolyamide yarn and elastane yam to obtain a fabric,
6
CA 03002488 2018-04-18
WO 2017/072127
PCT/EP2016/075700
b) heat-setting said fabric at a temperature not higher than 160 C over a time
period not higher than 100 seconds; and, optionally,
c) dyeing the fabric thus heat-set.
In step a) of the process, a fabric is obtained according to procedures known
in the field.
Preferably, the fabric is obtained by circular knitting with stitching of the
two yarns.
More preferably, the fabric has jersey stitch or interlock stitch.
For the purposes of the present invention, the knitting looms are selected on
the basis of
the gauge of the stitches they produce; preferably, gauge E (expressed as
"number of
needles per English inch") ranges from E20 to E50.
In particular, the jersey fabric is obtained with a single knit machine, while
the interlock
fabric is obtained with a double knit machine.
In step b) of the process, the step of heat-setting of the fabric obtained in
step a) is
performed.
Heat-setting is a thermal treatment for setting the fibers, imparting
dimensional stability
to the fabric and constancy of mass per unit area of the finished fabric.
The thermal treatment may be carried out with various heat sources:
- warm air, in a tentering machine,
- steam under pressure, in vaporizer,
- warm water, in HT equipment.
For standard polyamide fabrics, the typical temperatures at which heat-setting
is carried
out are 190-195 C.
The biopolyamides allow the heat-setting temperature to bet lowered down to
about
165 C.
For standard elastic material fabrics, the typical temperatures at which heat-
setting is
carried out are 190-195 C.
It has been surprisingly found that by combining biopolyamide yarn and
elastane yarn
as described above, it is possible to obtain a heat-set fabric having
excellent elastic
properties and high dimensional stability by carrying out the heat-setting
step b) at a
temperature not higher than 160 C. This allows a clear advantage in terms of
energy
consumption and production efficiency, because the processing time is reduced,
all
without impairing the technical features of the fabric, such as softness to
the touch and
bioelasticity, while preserving the original and brilliant colors.
7
CA 03002488 2018-04-18
=
WO 2017/072127
PCT/EP2016/075700
This result is even more surprising when considering that, for the Easy Set
LYCRA
yarns marketed by Invista, the temperature indicated by the manufacturer for
heat
setting is 170-175 C.
Therefore, the combination of yarns of the invention goes beyond the already
substantial advantages of the single yarns as compared to traditional yarns
considered
individually.
Preferably, the heat-setting step b) is carried out over a time period of 30-
70 seconds,
more preferably 40-45 seconds.
Preferably, the heat-setting step b) is carried out at a temperature of 100-
160 C, more
preferably of 120-160 C.
Optionally, the process also comprises a step c) of dyeing the heat-set
fabric.
Said step may be carried out according to techniques known in the field,
however,
dyeing is preferably carried out in overflow machines at atmospheric pressure.
In this
type of machines, the fabric moves at variable speeds within the bath which
consists of
water, auxiliary products and dyes. The maximum temperature achievable is
lower than
100 C.
In preferred embodiments, the dyeing step c) comprises the following substeps:
i) scouring at 80-100 C for 10-20 minutes, preferably at 90 C for 15 minutes,
ii) neutralizing the scouring at 50-70 C for 5-20 minutes, preferably at 60 C
for 10
minutes,
dyeing, with dye dosage for 15-30 minutes at 90-110 C with permanence for 20-
40 minutes, preferably for 24 minutes at 98 C with permanence for 30 minutes,
iv) stripping at 30-50 C for 5-20 minutes, preferably at 40 C for 10 minutes,
v) treating with a fixer at 50-90 C for 10-30 minutes, preferably at 70 C for
20
minutes, and
vi) final cold washing.
After this step, the dyed fabric is discharged from the machines and opened,
using a
specific machinery.
Thereafter, the fabric is dried. Preferably, drying is carried out in a
tentering machine at
a speed of about 20 meters per minute at a temperature of 90 C.
In another aspect, the present invention relates to a bielastic fabric
obtainable by the
process described above, said bielastic fabric comprising biopolyamide yarn
and
8
CA 03002488 2018-04-18
WO 2017/072127
PCT/EP2016/075700
elastane yarn.
The fabric thus obtained is very soft, comfortable and technical. It is
therefore
especially suitable for sea garments, such as swimwear, underwear and
sportswear.
In a further aspect, therefore, the present invention also relates to a
clothing item or a
furniture item, at least partially made of the bielastic fabric of the
invention.
By "clothing item" it is meant any article of clothing for men, women or
children, such
as shirt, pant, skirt, jacket, dress, shirt, blouse, sweater, as well as
accessories such as
handbags, briefcases, wallets, purses, key cases, cases for phones and
tablets. In
particular, it means clothing items suitable as sea garments, such as
swimwear,
underwear and sportswear.
"Furniture item" is meant to include any home linen article, such as
bedspreads,
curtains, tablecloths and linen for pillows, benches, armchairs, sofas,
chairs, beds and
ottomans.
It is to be understood that all aspects identified as preferred and
advantageous for the
bioelastic fabric should be deemed as similarly preferred and advantageous
also for the
manufacturing process and the bioelastic fabric obtained thereby, as well as
for the
clothing item or furniture item.
All the combinations of preferred aspects and embodiments of the bioelastic
fabric, of
the preparing process and of the bioelastic fabric obtained thereby, as well
as of the
clothing item or furniture item set forth above are further understood as also
described.
The following are non-limiting working examples of the present invention.
EXAMPLES
Example 1.
A Jersey fabric was produced, having basis weight 195 g/sqm and comprising 83%
of
biopolyamide yarn (count 88 dTex) and 17% of elastane yarn (count 44 dTex), by
knitting a biopolyamide yarn 6.6 (marketed as Fulgar Bio@ by Fulgar SpA) and
an
elastane yarn (marketed as Easy Set LYCRA by Invista) with circular knitting
in a
single knit machine (gauge E = E28).
The Jersey fabric thus obtained was subjected to heat-setting in a tentering
machine at a
temperature of 160 C over a time period of 40-45 seconds.
Thereafter, the dyeing step was carried out; the fabric was loaded in overflow
machines
and followed the following dyeing cycle:
9
CA 03002488 2018-04-18
WO 2017/072127
PCT/EP2016/075700
= scouring at 90 C for 15 minutes,
= neutralizing of the scouring at 60 C for 10 minutes,
= dyeing, dye dosage for 24 minutes at 98 C with permanence for 30 minutes,
= stripping at 40 C for 10 minutes,
= treating with a fixer at 70 C for 20
minutes, and
= final cold washing.
After this step, the dyed fabric is discharged from the machines and opened,
using a
specific machinery.
Thereafter, the fabric is dried in a tentering machine at a speed of about 20
meters per
minute at a temperature of 90 C.
The bielastic fabric thus obtained is shown in Figure 2 and has a basis weight
of 195
g/sqm, 60% elasticity in the weft and 50% elasticity in the warp. The
measurement of
the basis weight was obtained by taking a fabric round having a diameter of 11
cm and
weighing with a precision balance. Instead, the elasticity was measured by
taking 12 cm
long fabric strips and placing them in a dynamometer Zwick/Roell Z0,5.
Example 2.
A Jersey fabric was produced, having basis weight 115 g/sqm and comprising 76%
of
biopolyamide yam (count 28 dTex) and 24% of elastane yarn (count 22 dTex), by
knitting a biopolyamide yarn 6.6 (marketed as Fulgar Bio by Fulgar SpA) and
an
elastane yarn (marketed as Easy Set LYCRA by Invista) with circular knitting
in a
single knit machine (gauge E = E44).
The Jersey fabric thus obtained was subjected to heat-setting in a tentering
machine at a
temperature of 160 C over a time period of 40-45 seconds.
Thereafter, the dyeing step was carried out; the fabric was loaded in overflow
machines
and followed the following dyeing cycle:
= scouring at 90 C for 15 minutes,
= neutralizing of the scouring at 60 C for 10 minutes,
= dyeing, dye dosage for 24 minutes at 98 C with permanence for 30 minutes,
= stripping at 40 C for 10 minutes,
= treating with a fixer at 70 C for 20
minutes, and
= final cold washing.
After this step, the dyed fabric is discharged from the machines and opened,
using a
CA 03002488 2018-04-18
WO 2017/072127
PCT/EP2016/075700
specific machinery.
Thereafter, the fabric is dried in a tentering machine at a speed of about 20
meters per
minute at a temperature of 90 C.
The bielastic fabric thus obtained has a basis weight of 115 g/sqm, 160%
elasticity in
the weft and 160% elasticity in the warp. The measurement of the basis weight
was
obtained by taking a fabric round having a diameter of 11 cm and weighing with
a
precision balance. Instead, the elasticity was measured by taking 12 cm long
fabric
strips and placing them in a dynamometer Zwick/Roell Z0,5.
Example 3.
lo An Interlock fabric was produced, having basis weight 175 g/sqm and
comprising 77%
of biopolyamide yarn (count 28 dTex) and 23% of elastane yarn (count 22 dTex),
by
knitting a biopolyamide yarn 6.6 (marketed as Fulgar Bio by Fulgar SpA) and
an
elastane yarn (marketed as Easy Set LYCRA by Invista) with circular knitting
in a
double knit machine (gauge E = E40).
The Interlock fabric thus obtained was subjected to heat-setting in a
tentering machine
at a temperature of 160 C over a time period of 40-45 seconds.
Thereafter, the dyeing step was carried out; the fabric was loaded in overflow
machines
and followed the following dyeing cycle:
= scouring at 90 C for 15 minutes,
= neutralizing of the scouring at 60 C for 10 minutes,
= dyeing, dye dosage for 24 minutes at 98 C with permanence for 30 minutes,
= stripping at 40 C for 10 minutes,
= treating with a fixer at 70 C for 20 minutes, and
= final cold washing.
After this step, the dyed fabric is discharged from the machines and opened,
using a
specific machinery.
Thereafter, the fabric is dried in a tentering machine at a speed of about 20
meters per
minute at a temperature of 90 C.
The bielastic fabric thus obtained is shown in Figure 5 and has a basis weight
of 175
g/sqm, 150% elasticity in the weft and 70% elasticity in the warp. The
measurement of
the basis weight was obtained by taking a fabric round having a diameter of 11
cm and
weighing with a precision balance. Instead, the elasticity was measured by
taking 12 cm
11
CA 03002488 2018-04-18
,
WO 2017/072127
PCT/EP2016/075700
long fabric strips and placing them in a dynamometer Zwick/Roell Z0,5.
Example 4.
A Jersey fabric was produced, having basis weight 195 g/sqm and comprising 83%
of
biopolyamide yarn (count 88 dTex) and 17% of elastane yarn (count 44 dTex), by
knitting a biopolyamide yarn 6.6 (marketed as Fulgar Bio by Fulgar SpA) and
an
elastane yarn (marketed as Easy Set LYCRA by Invista) with circular knitting
in a
double knit machine (gauge E = E28).
The Jersey fabric thus obtained was subjected to heat-setting in a tentering
machine at a
temperature of 150 C over a time period of 50-55 seconds.
Thereafter, the dyeing step was carried out; the fabric was loaded in overflow
machines
and followed the following dyeing cycle:
= scouring at 90 C for 15 minutes,
= neutralizing of the scouring at 60 C for 10 minutes,
= dyeing, dye dosage for 24 minutes at 98 C with permanence for 30 minutes,
= stripping at 40 C for 10 minutes,
= treating with a fixer at 70 C for 20 minutes, and
= final cold washing.
After this step, the dyed fabric is discharged from the machines and opened,
using a
specific machinery.
Thereafter, the fabric is dried in a tentering machine at a speed of about 20
meters per
minute at a temperature of 90 C.
The bielastic fabric thus obtained has a basis weight of 195 g/sqm, 60%
elasticity in the
weft and 50% elasticity in the warp. The measurement of the basis weight was
obtained
by taking a fabric round having a diameter of 11 cm and weighing with a
precision
balance. Instead, the elasticity was measured by taking 12 cm long fabric
strips and
placing them in a dynamometer Zwick/Roell Z0,5.
12
