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Effect of elastane linear density on compression pressure of V-shaped compression socks

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The aim of this study was to evaluate the effect of elastane material linear densities on lateral compression values (ankle and calf) in newly designed shape (V-shape) compression socks. For this purpose, three types of yarns: main yarn (MY), plating yarn (PY) and inlaid yarn (IY) were used. Each yarn contains elastane material as core with varying linear densities. Firstly, Machine adjustments were optimized to achieve special V-shaped compression socks according to fix leg size. All the yarns were installed simultaneously and evaluated for their impact on compression pressure value at different segments of leg. Total eighteen socks samples were developed and quantified for pressure exertion using MST MKIV, Salzmann pressure monitoring device. All samples were analyzed using ANOVA in MINTAB 16 software. Consequently, only two socks samples finalized acquiring pressure exertion values of 21 mmHg and 23 mmHg with graduation percentage of 76% and 74% simultaneously.
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INTRODUCTION
Compression socks are highly recommended textile
garment for pressure exertion on the lower part of leg
[1]. Mechanism of action is a varying degree of com-
pression to different segments of the leg, with the
highest pressure at the ankle, must gradually
decrease in upward direction. These types of socks
are highly recommended for treatment of chronic
venous diseased patients [2]. Physical and construc-
tional properties of compression socks are of most
importance because its properties directly relate to
the type of patient and intensity of the disease. The
extent of compression that a patient can easily man-
age depends on stage (limb size and shape) of
venous disease and his activities (mobility, age).
Apart from above considerations, compression socks
must exert maximum pressure at the ankle, which
should decrease to the upper part of the limb. These
compression socks must acquire both comfortable
and appropriate level of compression. Medical com-
pression devices (MCD) are considered being more
effective in preventing and reducing edema if it is
capable to exert interface pressure on the gaiter area
up to 40 mmHg [3].
As per international classification of pressure exertion
intensity, it is classified as CCL1 (light) up to 20 mm Hg;
CCLII (moderate) 20–30 mmHg and CCLIII firm
compression (30–40 mmHg). These levels of pres-
sure exertion are recommended medically to treat cir-
culatory and vascular medical conditions as well for
tired, sore, swollen, or aching legs [3–6].
Theoretically, the amount of pressure in the circum-
ferential direction of leg depends on the radius (R) of
leg and reversal force T (N).
According to Laplace’s Law [5]
T (N)
P (Pa) =   (1)
R (cm)
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2018, vol. 69, nr. 2
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Effect of elastane linear density on compression pressure of V-shaped
compression socks
SIDDIQUE HAFIZ FAISAL HAVELKA ANTONIN
MAZARI ADNAN HUSSAIN TANVEER
REZUMAT – ABSTRACT
Efectul densităţii liniare a elastanului asupra presiunii de compresie a şosetelor de compresie cu fire
de vanisare
Scopul acestui studiu a fost de a evalua efectul densităţii liniare a materialelor din elastan asupra valorilor de compresie
laterale (gleznă şi gambă) a unor noi variante de şosete de compresie (cu fire de vanisare). În acest scop, au fost
utilizate trei tipuri de fire: fire de bază (MY), fire de vanisare (PY) şi fire de căpuşeală (IY). Fiecare fir conţine material
elastan drept miez cu densităţi liniare variabile. Reglajele maşinii au fost optimizate pentru a se obţine şosete de
compresie speciale cu fire de vanisare, în funcţie de dimensiunea fixă a piciorului. Toate firele au fost instalate simultan
şi evaluate pentru impactul lor asupra valorii presiunii de compresie la diferite segmente de picior. În total, au fost
dezvoltate şi cuantificate 18 probe de şosete pentru exercitarea presiunii utilizând dispozitivul MST MKIV, un dispozitiv
de monitorizare a presiunii Salzmann. Toate probele au fost analizate utilizând software-ul ANOVA în MINTAB 16.
În final, numai două probe de şosete au fost finalizate, obţinându-se valori de exercitare a presiunii de 21 mmHg şi
23 mmHg, cu un nivel de compresie graduală de 76% şi 74%, simultan.
Cuvinte-cheie: compresie, densitate lineară, elastan, şosete cu fire de vanisare, fir filat cu miez, fir acoperit, fir dublu
acoperit
Effect of elastane linear density on compression pressure of V-shaped compression socks
The aim of this study was to evaluate the effect of elastane material linear densities on lateral compression values (ankle
and calf) in newly designed shape (V-shape) compression socks. For this purpose, three types of yarns: main yarn (MY),
plating yarn (PY) and inlaid yarn (IY) were used. Each yarn contains elastane material as core with varying linear
densities. Firstly, Machine adjustments were optimized to achieve special V-shaped compression socks according to fix
leg size. All the yarns were installed simultaneously and evaluated for their impact on compression pressure value at
different segments of leg. Total eighteen socks samples were developed and quantified for pressure exertion using MST
MKIV, Salzmann pressure monitoring device. All samples were analyzed using ANOVA in MINTAB 16 software.
Consequently, only two socks samples finalized acquiring pressure exertion values of 21 mmHg and 23 mmHg with
graduation percentage of 76% and 74% simultaneously.
Keywords: compression, linear density, elastane, V-shaped socks, core spun yarn, air covered yarn, double covered
yarn
Where P = Pressure, T = Reversal fabric tension,
R= Radius of leg.
For the pressure measurement on a patient’s leg, cir-
cumference of the ankle and calf portion is required
(1), so the equation (1) can be modified to
T (N) × 2p
P (Pa) = (2)
C (cm)
Where P= Pressure, T= Reversal fabric tension,
C= Circumference of leg
or
T (N) × 2
P (Pa) = (3)
W (cm)
Where P= Pressure, T= Reversal fabric tension,
W= width of socks.
Using the Laplace's formula, it is evident that the
operating pressure should be greatest at the point of
the lowest girth area (ankle) and have the slightest
pressure at the point of maximum girth area (calf).
Apart from the position of the leg, the circumference
(thin or thick) of the leg also needs optimum or lower
pressure on cutaneous and subcutaneous skin layers
which satisfies the Laplace's Law [7].
Hui and Ng (2001) attempted to design a theoretical
model for prediction of interface pressure between
the skin and garment using multilayer fabric tubes. All
tubes have different tensile properties and compare
its validation. Designed model is given below.
2p(E1h1 + E2h2)
P= (4)
C
Where = axial strain, E= modulus of elasticity, h=
thickness of textile tube.
This model was experimentally verified by measuring
the tensile properties of elastic fabric exhibit breaking
load capacity up to 60 kg and breaking extension
capacity in both directions (warp and weft)up to 360%
using an Instron tensile strength machine (model
1026) under zero load, using the cut-strip test.
Specimen size selected 5 × 15 cm, gauge length 10
cm, specimen extended 5–60% lengthways at 5%
intervals, extended rate 200 mm/min; clamp width 5
cm (flat faces), tension load cell was 5 Kg. The ten-
sion force (Kgf) was recorded for each 10% stretch to
calculate the stress (N/m2) of a fabric specimen. In
order to obtain a stable stress-strain curve for an
elastic fabric, we ran a few cycles of extension and
relaxation before the test. Elastic tubes pressure was
measured using oxford MKII pressure monitoring
device at fix locations of cylindrical tubes under the
elastic fabric. This pressure values were compared
with the modulus properties were measured under
ASTM D2256-97.Theoretical and actual measure-
ments were compared and found the values to be
very closer [8].
Hui and Ng (2001) attempted to design pressure
model for the human leg interface pressure by the
compression garment given below. They selected
warp knitted elastic fabric and compared these pres-
sure values using Oxford MKII pressure monitoring
device between human body skin and donned gar-
ment
1
Re = (5)
2p EI (CF)
1 +
C human + F
They concluded that compression factor is very
important parameter. Instead of using a trial and error
approach, this proposed pressure model could help
therapists to make pressure garments more effec-
tively and efficiently [9].
Normally, compression socks are recommended for
the patients who have stabilized leg circumference
and no longer edema. In this situation the socks will
correspond effectively to a minor increase in leg cir-
cumference. It is also recommended for optimal com-
pression, these would be donned early in the morn-
ing when edema is reduced.
A few of the studies are there in which proper devel-
opment of socks has been done, but mostly
researcher had worked on manufactured socks.
Liu et al. (2005) investigated the effect of different
material properties and fabric structure characteris-
tics of graduated compression stockings (GCS) on
the Skin Pressure Distributions. For this study, they
selected eight different commercially available stock-
ings comprised of polyamide and elastane material of
varying composition. They concluded that structural
characteristics and material properties of stockings
were not even along the length of the leg except
gradual variation of compression pressure from ankle
to thigh which significantly influenced the corre-
sponding skin pressure gradient distributions [10].
Partsch et al. (2006) studied interface pressure and
stiffness of ready-made compression stockings. In
this study the interface pressure of several medical
compression stockings was measured on 12 legs
from six employees (5 women, 1 man) having their
mean ages 43.2 years (range, 20 to 61). Calf-length
compression stockings of the European classes I, II,
III and the two class I socks over each other were
applied on 12 legs. Interface pressure was measured
using MST tester using wooden leg models. It was
concluded that in vivo and in vitro measurement, an
increase in stiffness causes the increase in compres-
sion pressure. The highest values are found for two
class I stockings applied over each other [8].
Gaieda et al. (2006) used the combination of main
yarn as well as inlaid yarn having Lycra in core
wrapped by polyamide. The objective was to obtain
compression pressure up to 30 mm of Hg, but
observed no significant results except 20 mm of Hg
was achieved [11].
Maleki et al. (2011) investigated the effect of different
stitch lengths (0.22 cm, 0.25 cm, 0.27 cm, 0.29 cm
and 0.32 cm) and repeated usages on two different
types (plain and interlock) of knitted structures. They
concluded that stitch length is significant parameter,
as it increases; there occurs a decrease in pressure
and vice versa. While interlock structured fabrics
exhibit higher stitch length so display more pressure
reduction [12].
Dalbey et al. (2011) had patented their work using
core spun yarn having sheath of Polyester as a main
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2018, vol. 69, nr. 2
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yarn and double covered Nylon yarn on Lycra core as
inlaid yarn achieved maximum compression up to
40 mm of Hg [13].
Troynikova O et al. (2013) studied the influence of
material properties and garment composition on the
pressure generated by sport compression garments
using two differently structured knitted fabrics with
different physical properties and elastic performance.
These samples were tested using compression pres-
sure measuring device MST MK IV. The researchers
concluded that different material composition of fab-
ric assemblies influenced the pressure delivery of
garment [14].
Normally, socks (weft knitted) are composed of three
yarns types defined body yarn, plated yarn and inlaid
yarn. Body yarns as in direct contact with skin pro-
vide different feels to wearer. Inlaid yarns used are
single covered or double covered yarns that run
through the heads of loop form by body yarn. It con-
trols stretch, optimum pressure, intimate contact and
grip over the leg portion and avoids the sliding of the
socks. The loop-forming yarns like body yarn (spun/
filament) and plated yarn (air covered) form the loops
together. Inlaid yarn (double covered yarn) is inte-
grated into each loop of every course [13–16].
Various studies exits in which different fiber/yarn
types (varying elastane linear densities and composi-
tions) different types of spun/core spun yarns of dif-
ferent linear densities, different kind of inlaid yarn,
varying tension by increasing or decreasing ultra
feeder yarn tensions into knitting machine and differ-
ent fabric structures (manufactured and ready-made),
different sizes and shapes of the substrate (cylindri-
cal tube or wooden leg) had been used to exert max-
imum pressure at the ankle and optimum graduation
[2, 4, 14, 16–18]. But there is no study in which the
effect elastane material linear densities used in all the
three socks components body yarn, plated yarn and
inlaid yarn is studied in specially
designed V-shaped socks.
In normal compression socks
graduation percentage varies
from 60% to 80% of the total
compression pressure at the
ankle. The most important prop-
erty required in graduated com-
pression socks is to attain the
highest sub-garment compres-
sion pressure at ankle according
to European classification of com-
pression pressure. The gradua-
tion compression pressure means
gradually lowering of pressure along the length of the
leg towards the calf. If does not reduces while mov-
ing upward may cause blood clotting and swelling of
inner walls of the veins. The intensity of compression
pressure suggested for the patients depends on the
type, history and intensity of the disease. The severe
is the disease, the higher compression pressure sug-
gested for the patient to prevent the recurrence of
lymph edema.
The objective of this study is to investigate the influ-
ence main yarn (MY), plating yarn (PY), and inlaid
yarn (IY) on compression pressure at ankle, calf and
graduation percentage between 70 to 80%.
MATERIALS AND METHOD
Materials (yarns)
Compression socks are comprised of three yarns
types i.e. main, plated and inlaid abbreviated as main
yarn (MY), plating yarn (PY) and Inlaid yarn (IY).
Main/Body yarn: Three types of main yarns (core
Spun) were selected abbreviated as (MY1*, MY2* &
MY3*) as shown figure 1. All have same Overall lin-
ear density i.e. 29.52 tex but different elastane mate-
rial linear densities i.e. 4.4 tex, 7.77 tex, 11.7 tex
respectively. Here *MY1: 4.4 tex Lycra-29.52/1 tex
core spun cotton 96%, *MY2: 7.8 tex Lycra-29.52/
1 tex core spun cotton 93% and *MY3: 11.7 tex
Lycra-29.52/1 tex core spun cotton 90%. Testing
results of main yarn are given below in table 1.
Inlaid yarn: Three types of double covered Nylon fil-
ament yarn were selected as shown in figure 2 can
be abbreviated as (IY1*, IY2*& IY3*). Each type con-
tains elastane yarn of different linear densities i.e.
13.3 tex, 15.5 tex and 33 tex but fixed sheath yarn
linear density i.e. 15.55 tex/24f/1. Here *IY1: 13.3 tex-
15.55/ 24f/1 tex Raw White Nylon DCV 17%, *IY2:
15.50 tex-15.55/24f/1 tex Raw White Nylon DCV
19% and *IY3: 33.0 tex-15.55/24f/1 tex Raw White
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Sr. no Main yarn codes Yarn linear density (tex) Draw ratio Elastane composition (%)
Resultant Elastane
1 MYELD1 29.52 4.4 3.48 4.32
2 MYELD2 29.52 7.8 3.64 7.22
3 MYELD3 29.52 11.7 3.65 10.83
Table 1
MY: Main Yarn, E: Elastane, LD: Linear Density
Fig. 1. Front view of
Core Spun yarn [12] Fig. 2. Double covered Nylon Filament yarn [19]
Nylon DCV 34% (DCV: Double covered). Testing
results of inlaid yarns are given in the table 3.
Plating yarn: Two types of nylon air covered yarns
were selected abbreviated as (PY1* & PY2*) as
shown in (figure 3) having different draft values (2%
& 3.2%) were selected. Here *PY1: 2.2 tex Lycra-
7.77 tex/24 filamnet/1 Raw White Nylon ACV 8%,
*PY2: 2.2 tex Lycra-7.77 tex/24 filament/1 Raw White
Nylon ACV 12.5% [ACV: air covered]. Testing results
of plating yarn are given in table 2.
Method
Machine specifications
Technical specifications of selected conventional
machine are given below in table 4.
Optimization of machine adjustments
In this section, we adjusted the conventional socks
knitting machine to 2 steps special settings to achieve
desired V-shape ribbed socks. Step (I): Gradient
change in the Degree of needles for main and plating
yarns Step (II): Varying graduation motor speed for
Inlaid yarn as shown in figure 4 and figure 5. Total
322 courses were inserted in the rib portion (1×1) of
each socks sample.
Main yarn and plating yarn insertion were divided into
three zones of varying degree of needles. In each
zone, 108 courses were inserted
with decreasing degree of nee-
dles from the calf portion (400
degree) to ankle portion (100
degree). A zone with the lowest
degree (100) of needles was
introduced at the ankle portion
as required lowest loop height to
exert highest pressure and high-
est degree (400) at calf portion
is required to attain lower pressure at calf than ankle.
Inlaid yarn insertion was divided into seven zones
and controlled by varying graduation motor speed
from 600 rpm to 1400 rpm from calf to ankle. In seven
zones, each zone contains 46 courses with reduction
of constant speed of 200 rpm of graduation motor at
each zone out of seven.
After optimization of machine adjustments, V shape
socks were manufactured at above mentioned set-
ting, but with changing types of yarns.
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a   b
Sr. no Plating yarn
codes
Yarn linear density (tex) Elastane
ACV Sheath Elastane Draw ratio (%) Composition (%)
1 PYED1 9.11 7.77 2.2 3.2 8
2 PYED2 9.44 7.77 2.2 2 12.5
Table 3
Model Company Cylinder Gauge Diameter Speed Feeder Needles
L462 2005 Lonati Single 12 3.75″ 250 rpm 2 168
Table 4
Fig. 3. Side view of ACV yarn:
a– resultant and elastane diameter; b– scanned plated air covered yarn [20]
PY: Plated Yarn, E: Elastane, D: Draft
Fig. 4. Schematic diagram of elastic motor
Sr. no Inlaid yarn codes Yarn linear density (tex) Draw ratio Elastane composition
(%)
DCV Resultant Nylon Elastane
1 IYELD1 20.22 15.55 13.3 1.63 17.27
2 IYELD2 21.11 15.55 15.5 1.85 18.6
3 IYELD3 27.33 15.55 33 1.56 34.08
Table 2
IY: Inlaid Main, E: Elastane, LD: Linear Density
Preparation of V shaped socks
Three yarns (main, plating and Inlaid) were loaded on
socks knitting machine at above mentioned adjust-
ments. Desired V- shape socks are shown in figure 5.
Physical specifications of socks samples and
wooden leg
Widths (diameter) of all the socks samples were
measured at the ankle (6.5 cm to 8.5 cm) and a calf
portion (9 cm to 10.5). This difference in widths is due
to machine adjustments and varying linear densities
of elastane materials. Width measurements of the
socks samples and wooden leg are given below in
table 5.
Pressure measurement of V-shaped socks
Compression pressure of all the socks samples was
measured using MST MK IV SALZMANN compres-
sion tester under standard test method of ENV 12718
as shown in figure 6. The device consists of a thin
plastic sleeve (4 cm wide, 0.5 mm thick), with four to
six paired electrical contact points. The measuring
points are B, ankle; B1, gaiter area; C, largest calf cir-
cumference; and D, below knee as shown in figure 6,
connected to an air pump and a pressure transducer.
This probe is placed between the leg and the com-
pression device. The air pump at rate of 1 mmHg/sec
inflates the wrapper until the contacts open. The con-
tact of compression garment to wooden leg is dimin-
ished when the inner pressure exerted by the air is
just above external pressure due to the compression
device. When the contact opens, the transducer
reads the pressure at each measuring point and the
pressure value displayed digitally with 1-mmHg reso-
lution [1].
Compression pressure values at ankle portion, calf
portion and graduation percentage (G%) was calcu-
lated. G% is a very important factor keep in mind as
helpful to regulate the blood flow. Liu et al. (2005)
studied that the compression socks should exert
maximum pressure at ankle decreasing to upward
(hip side) [4]. This gradient change in pressure, gen-
erate the pressure between capillaries and enhance
the rate of blood flow through the veins [1].
Graduation percentage (G%) from ankle to calf por-
tion is calculated using formula
Graduation percentage (G%) = (Pᶜ ÷ Pᵃ) ×100 (6)
Pᶜ = Pressure at calf portion, Pᵃ = Pressure at ankle
portion (16).
RESULTS AND DISCUSSION
Compression properties
The experimental variables are: main yarn elastane
linear density (MYELD), plating yarn elastane draft
(PYED) and in-laid yarn elastane linear density
(IYELD). Table 6 shows compression pressure val-
ues of developed socks at the ankle, at the calf and
the percentage graduation.
Effect of elastane linear densities (main and
Inlaid) and draft (plated) at ankle
Effect of elastane linear densities used in all socks
samples at the ankle was analyzed first using ANOVA
tool (Statistical software MINITAB). In this case to
construe whether the parameters are significant or
not, p values are examined. As known, if the ‘p’ value
of a parameter is greater than 0.05 (p > 0.05), the
parameter will not be statistically significant. ANOVA
values of compression pressure at ankle are shown
in table 7.
The analysis of variance data shown in table 4 indi-
cates that the p-value of effect of main yarn elastane
linear density (MYELD) and inlaid yarn elastane lin-
ear density (IYELD) is below 0.05 which depict the
significant influence of input variables on compres-
sion pressure at ankle while the impact of plating
yarn elastane draft on compression pressure at ankle
is non-significant (p > 0.005).
Figure 7 and figure 8 portray the trend of main yarn
elastane linear density, inlaid yarn elastane linear
density and plating yarn elastane draft on exertion
pressure at ankle.
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Fig. 6. Schematic diagram of MST MKIV Salzmann
pressure-measurement device
Sr.
no.
Socks
width
Unit
(cm)
Wooden leg width
(cm)
1 Ankle 6.5–8.5 8.28
2 Calf 9–10.5 12.42
Table 5
Fig. 5. V-shaped compression socks prepared
on conventional knitting machine
Figure 7 and figure 8 demonstrate that as the linear
density of the elastane material of the main yarn
increases from 44 detx to 78 detx, increase in
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Sr.
no.
Code
detail
MYELD
[dtex]
IYELD
[dtex]
PYED
[ratio]
Pressure at ankle (Pa)
[mmHg]
Pressure at calf (Pc)
[mmHg]
Graduation
[%]
1 M1I1P1 44 133 2 13 11 84.61
2 M1I1P2 44 133 3.2 15 14 93.3
3 M1I2P1 44 155 2 13 11 84.6
4 M1I2P2 44 155 3.2 13 14 107.69
5 M1I3P1 44 330 2 21 16 76.19
6 M1I3P2 44 330 3.2 23 17 73.91
7 M2I1P1 78 133 2 16 14 87.5
8 M2I1P2 78 133 3.2 18 16 88.8
9 M2I2P1 78 155 2 17 15 88.23
10 M2I2P2 78 155 3.2 18 17 94.44
11 M2I3P1 78 330 2 26 22 91.66
12 M2I3P2 78 330 3.2 24 22 91.66
13 M3I1P1 117 133 2 17 16 94.11
14 M3I1P2 117 133 3.2 16 16 100
15 M3I2P1 117 155 2 19 16 84.21
16 M3I2P2 117 155 3.2 17 18 105.88
17 M3I3P1 117 330 2 22 22 100
18 M3I3P2 117 330 3.2 23 22 95.65
Table 6
Source DF Adj. SS Adj. MS F-value P-value
Model 13 243.114 18.7011 24.57 0.004
Linear 5 230.112 46.0223 60.46 0.001
MYELD 2 40.148 20.0741 26.37 *0.005
ILELD 2 189.561 94.7807 124.51 *0.000
PYED 1 0.402 0.4020 0.53 0.508
Error 4 3.045 0.7612
Total 17 246.159
Table 7
* Significant variables
Fig. 7. Main yarn elastane linear density (MYELD),
Plating yarn elastane Draft (PYED) and inlaid yarn
elastane linear density (IYELD) Vs compression
pressure (mm Hg) at ankle
Fig. 8. Surface plot of pressure at ankle(mm Hg) Vs
Main yarn elastane linear density (MYELD), and
inlaid yarn elastane linear density (IYELD)
M1, M2 & M3 = Main Yarns, I1, I2 & I3: Inlaid yarns, P1 & P2 = Plated Yarns
compression pressure from 16 mm Hg to 19 mm Hg
at ankle takes place. But as the linear density of elas-
tane material increases more from 78 detx to 117
dtex, a non-significant decrease in compression
pressure at ankle from 19 mm Hg to 18 mm Hg takes
place. Increase in compression pressure from 16 mm
Hg to 19 mm Hg by increasing the linear density of
the elastane material is due to increase in the con-
traction of the socks. The fabric density at ankle
increases as the linear density of the elastane mate-
rial increases, which gradually reduces loop length
and air spaces while increasing the stiffness and
compactness of the fabric. As the linear density of the
main yarn elastane material increases more 78 dtex
to 177 dtex, there observed a slight decrease in com-
pression pressure. The reason of decrease in com-
pression pressure is due to additional compact-
ness/least air spaces in knitted fabric which do not
allow the fabric to contract more than the size of the
wooden leg minimum girth area (ankle) ultimately
reducing the compression pressure at ankle. The
wooden dummy used in this study has width/circum-
ference (cm) 8.28/26 cm while the prepared socks
has the width range from 6 cm ~7.5 cm that when
worn to leg size it is stretched to extent according to
circumference of the leg.
Inlaid yarn is the yarn which moves transversely
along each course of main yarn loops while missing
the one loop of the wale (rib construction 1×1). It is
evident from the figure 7 and figure 8 that as the lin-
ear density of the elastane material increases from
133 dtex to 155 dtex, a slight increase in compression
pressure from 15 mm Hg to 16 mm Hg takes place
but as the linear density of the inlaid yarn increases
from 155 dtex to 330 dtex, incredible increase in
compression pressure from 16 mm Hg to 23 mm Hg
takes place.
Diana et al. (2013) reported that the linear pressure
depends on the linear density of the PU core materi-
al and insertion density of the inlaid yarn. She also
reported that extensibility of the socks can be con-
trolled (transversely and longitudinally) by the
increasing or decreasing insertion density of the
inlaid yarn according to requirement [23].
Pressure at Ankle (mm Hg) = 2.03 + 0.3094 MYELD +
+ 0.03681 IYELD – 0.001693 MYELD * MYELD (7)
R-Sq. for the regression equation (1) is 93% which
signifies that 93 % change in compression pressure
at ankle can be explained by the terms included in
the equation.
Effect of elastane linear densities (main and
inlaid) and draft (plated) at calf
Analysis of developed compression socks at calf was
made using statistical software called as MINITAB.
For the statistical importance of the experimental fac-
tors, analysis of variance (ANOVA) tool was applied.
In order to construe whether the parameters were
significant or not, p values were examined. As
known, if the ‘p’ value of a parameter is greater than
0.05 (p > 0.05), the parameter will not be statistically
significant.
The analysis of variance data shown in table 8 indi-
cates that the p-value of main yarn elastane linear
density (MYELD) and inlaid yarn elastane linear den-
sity (IYELD) and plating yarn elastane draft is below
0.05 which depict the significant influence of input
variables on the compression pressure at calf.
Figure 9, 10 and 11 represents the impact of main
yarn elastane linear density, inlaid yarn elastane lin-
ear density and plating yarn elastane draft on the
exertion pressure at the calf.
Main yarn is usually in contact with the skin and
forms the wales and courses in the socks, which
transversely and longitudinally affect the socks size
and compactness of loops in knitted fabric. Figures 9,
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Source DF Adj. SS Adj. MS F-value P-value
Model 13 224.590 17.2762 25.32 0.003
Linear 5 211.697 42.3394 62.05 0.001
MYELD 2 65.091 32.5453 47.69 *0.002
ILELD 2 141.006 70.5032 103.32 *0.000
PYED 1 5.600 5.6001 8.21 *0.046
Error 4 0.6824 0.6824
Total 17 227.320
Table 8
*Significant variables
Fig. 9. Main effect plot of main yarn elastane linear
density (MYELD), Plating yarn elastane draft (PYED)
and inlaid yarn elastane linear density (IYELD) Vs
compression pressure (mm Hg) at calf
10 and 11 show that as the linear density of the elas-
tane material of main yarn increases from 44 dtex to
78 dtex, the incredible increase in compression pres-
sure from 13 mm Hg to 17 mm Hg takes place. As the
linear density of elastane material increases more
from 78 dtex to 117 dtex, a slight increase in com-
pression pressure at the calf is observed.
Increase in compression pressure from 13 mm Hg to
17 mm Hg is due to increase in fabric contraction.
The fabric density at calf increases as the linear den-
sity of the elastane material increases which gradual-
ly reduces loop length while increasing the stiffness
and compactness of the fabric. As the linear density
of the main yarn elastane material increases, there
occurs a slight decrease in compression pressure.
The reason of increase in compression pressure at
thr calf is an increase in contraction that occurs in
transverse and longitudinal directions.
In this study, we have changed the degree of needles
which decreases from the calf portion (600) of the
socks to ankle portion (300). The higher degree of
needle causes the loose construction of the knitted
fabric. This loose construction of the fabric allows it to
stretch more as compared to the width of the calf.
The socks prepared have the width ranged at calf
from 24.13 mm to 26.67 mm (circumference 76.2 mm
~ 83.82 mm while the wooden dummy used in this
study has a circumference of 37 cm (93.98 mm). This
gradual increase in wooden dummy calf circumfer-
ence shows less compatibility of the socks with the
wooden leg. Consequently, due to the higher circum-
ference of the wooden leg, extensibility of the socks
and compression pressure at calf increases while
increasing the size of pores.
Inlaid yarn has also a significant impact on the com-
pression pressure at the calf. It is depicted from the
figures 9, 10 and 11 that as the linear density of the
inlaid yarn increases from 133 dtex to 155 dtex as a
significant increase in compression pressure from
13 mm Hg to 14 mm Hg take place. It drastically con-
tinues to increase when the linear density of the inlaid
elastane yarn increases from 155 dtex to 330 dtex.
Hence, the intensity of the pressure can be increased
or decreased by increasing or decreasing the degree
of needles and speed of the elastic motor according
to requisite graduation level and to achieve the
desired class of compression level.
Pressure at Calf, mm Hg = –4.77 + 0.2734 MYELD +
+ 0.03171 IYELD + 0.930 PYED –
– 0.001336 MYELD * MYELD (8)
R-Sq. for the regression equation (2) is 92% which
indicates that 92 % change in compression pressure
at calf can be explained by the terms included in the
equation.
CONCLUSIONS
In this study it was concluded that,
Main yarn elastane linear density (MYELD) has sig-
nificant impact on the compression pressure at the
ankle. As the linear density of the main yarn elastane
material increases from 44 dtex to 78 dtex an
incredible increase in compression pressure from
16 mm Hg to 19 mm Hg takes place at ankle. The
same effect of compression pressure at calf was
observed which was increased from 13 mm Hg to
17 mm Hg and then to 18 mm Hg with consecu-
tively increase of linear density of the main yarn 44
dtex to 78 dtex and then to 117 detx.
Inlaid yarn elastane linear density (IYELD) has sig-
nificant impact on the compression pressure at the
ankle. As the linear density of inlaid yarn elastane
material linear density increases from 133 dtex to
155 dtex and then to 330 dtex, a significant
increase in compression pressure from 15 mm Hg
to 16 mm Hg and incredible increase to 23 mmHg
at the ankle was observed. The same significant
influence of increase of linear densities of the inlaid
elastane linear density from 133 dtex to 155 dtex
and then to 330 dtex on compression pressure
value at calf portion was observed ranging from
15 mm Hg to 16 mm Hg and then to 21 mm Hg.
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2018, vol. 69, nr. 2
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Fig. 11. Surface plot of main yarn elastane linear density
(MYELD) and plating yarn elastane (PYED) draft
Vs compression pressure (mm Hg) at calf
Fig. 10. Surface plot of main yarn elastane linear density
(MYELD), and Inlaid yarn elastane linear density (IYELD)
Vs compression pressure (mm Hg) at calf
Plated yarn elastane draft (PYED) has non-signifi-
cant influence on the compression pressure at the
ankle and calf as well. As the draft value of plating
yarn elastane draft increases from 2 to 3.2, a non-
significant change in compression pressure at
ankle from 18 mm Hg to 18.5 mm Hg and at calf
from 16 mm Hg to 17 mm Hg was observed.
Out of all newly developed V-Shape compression
socks, we segregate them on the basis of gradua-
tion% values which must lies between 60% and
80%. So, on the basis of this abnormality, we reject-
ed all the socks samples that possess graduation
percentage above 80% i.e. 85% to 105% which
cannot be recommended for compression therapy.
For this, we found only the two samples socks,
M1I3P1 and M1I3P2 acquiring excellent graduation
percentages i.e. 76.19 % and 73.91%.
Finally, we concludedthat only two socks samples
(M1I3P1 and M1I3P2) that acquire maximum com-
pression pressure at the ankle of about 21 mm Hg
and 23 mm Hg along with excellent graduation per-
centages i.e. 76.19% and 73.91%.These socks
samples (M1I3P1 and M1I3P2) can fulfill the com-
pression pressure of class II as per UK, USA, and
EU standards and of compression class III as per
French standards.
ACKNOWLEDGEMENT
This work was supported by the Ministry of Industry and
Trade of the Czech Republic, Programme Trio – project
"Senior Tex – Smart Modular Clothing and Textile Products
with Integrated Electronic Microsystems for Improving the
Health Care of the Aging Population and Handicap
People", reg. no. FV10111 as well as under the project of
Student Grant Scheme SGS-18. Project reference number
is 21246.
126
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2018, vol. 69, nr. 2
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Authors:
SIDDIQUE HAFIZ FAISAL1
MAZARI ADNAN1
HAVELKA ANTONIN1
HUSSAIN TANVEER 2
1 Technical University of Liberec, Faculty of Textile Engineering
Studentská 1402/2, 461 17 Liberec 1, Czech Republic
2 National Textile University, Textile Engineering
Sheikhupura Road, Manawala 37610, Faisalabad, Pakistan
e-mail: faisalsiddique3648@gmail.com, adnanmazari86@gmail.com, antonin.havelka@tul.cz,
mehr_azam91@yahoo.com, hussain.tanveer@gmail.com
Corresponding author:
SIDDIQUE HAFIZ FAISAL
e-mail: faisalsiddique3648@gmail.com
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