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EFFECT OF LYCRA AND NYLON YARN PERCENTAGE
ON THE DIMENSIONAL AND PHYSICAL 
CHARACTERISTICS OF LOCKNIT WARP KNITTED
FABRICS
LIBRARY
UliVERSfTY OF MORATUWA, SRI LANKA 
MORATUWA
D.M.S.Dissanayaka
(109128 B)
Thesis submitted in partial fulfillment of the requirements for the degree Master of
Science ;i. v \C ho-oo f’Vs A;? 0 ;VM ,
c
Department of Textile & Clothing Technology
Stt ' \ 3
University of Moratuwa 
Sri Lanka
0 :.j Co-i 50 77 -
109 oq?
March 2015
Th29£)8University of Moratuwa
109007
109007
DECLARATION, COPYRIGHT STATEMENT AND THE STATEMENT OF 
THE SUPERVISOR
“I declare that this is my own work and this dissertation does not incorporate without 
acknowledgement any material previously submitted for a Degree or Diploma in any 
other University or Institute or higher learning and to the best of my knowledge and 
belief it does not contain any material previously published or written by another 
person except where the acknowledgement is made in the text.
Also, I hereby grant to University of Moratuwa the non-exclusive right to reproduce 
and distribute my dissertation, in whole or in part in print, electronic or other medium. I 
retain the right to use this content in whole or part in future works (such as articles or 
books).
Signature: Date: 10.03.2015
The above candidate has earned out research for the Masters dissertation under my 
supervision.
IO - o l.
Date:Signaturl tne supervisor:
11
Abstract
The effects of different percentages of elastane and Nylon yam on the dimensional and 
physical properties of elastane/Nylon Locknit warp knitted fabrics are investigated. In order 
to investigate the properties of the fabric, four different samples were knitted by selecting four 
different run-in ratios of elastane and Nylon. Elastane yam was kept at a constant elongation 
of 65% for all four samples. Two samples were produced keeping constant run-in of nylon 
yam and changing the run-in length of elastane yarn. Then elastane yam run-in was kept 
constant and produced two other samples.
The sample with minimum run-in length of elastane yam and the highest run-in ratio has the 
highest value of load at 20%, 40%, 60% and 80% extensions in length direction and the 
lowest values of load at 20%, 40%, 60% and 80% extensions in width direction. This is due to 
the fact that low run in of elastane yam increases the strain on the yam and it increases the 
tightness factor value of the sample and contributes higher load at extension along the length 
direction of the greige sample. Nylon yam runner length influences the relaxation behavior of 
elastane yarn and it leads to reduce the load at extension along the width direction of the 
sample.
Changing of Nylon yam runner length influence the relaxation behavior of elastane yam and 
it has an effect on the load at different extension in width direction and course density of the 
greige fabric. Results revealed that the effect of elastane content of the sample is more on the 
load at extension values than the effect of run-in of the Nylon yam.
Key words Greige fabric, Run-in, elongation, load at extension, course density'
ill
ACKNOWLEDGEMENT
I take this opportunity to express my profound gratitude and deep regards to my 
supervisor Dr. W.D.G.Lanarolle, head of department, department of textile and clothing 
technology, University of Moratuwa for his exemplary guidance, monitoring and 
constant encouragement throughout the course of this thesis
I also take this opportunity to express a deep sense of gratitude to Adjunct professor 
Rohana Kuruppu, Mr.AsokaWalpitigama and Mr. Ranjan Nishantha, Brandix college 
of Clothing Technology for their cordial support, valuable information and guidance, 
which helped me in completing this task through various stages.
I am obliged to staff members of Trishel Fabric (pvt) Ltd, Specially Mr.Heshana 
Kuruppu and Mr. Champika Liyanage for giving me the opportunity to produce the 
fabrics and providing valuable information in their respective field. I am grateful for 
their cooperation during the period of my assignment.
I would to thank Mr.G.K.K.Kumara Laboratory Manager and the staff of Textile 
Laboratory in Sri-Lanka Institute of Textile and Apparel and Ms. Dilum Dissanayaka of 
Physical Testing and Quality control laboratory, Department of Textile and Clothing 
Technology, University of Moratuwa for their valuable assistance during the period of 
my assignment
Lastly, I thank almighty, my parents, brothers, sister and friends for their constant 
encouragement without which this assignment would not be possible.
IV
TABLE OF CONTENTS
Declaration of the candidate & Supervisor 1
Abstract 11
Acknowledgement in
Table of content iv
List of Figures Vll
List of Tables vm
List of abbreviations IX
Chapter 1: Introduction 1
1.1 Background of the study 1
1.2 Problem description 2
Objective of the study1.3 4
Chapter 2: Literature Review 5
2.1 Introduction 5
2.2 Introduction to warp knitted fabric 5
2.2.1 Formation of loop structure 6
2.2.2 Open and close loop 7
2.2.3 Types of warp knitted fabrics 7
2.2.4 Technical face & back of the fabric 8
2.2.5 Locknit Fabric 8
2.2.6 Fabric geometry of warp knitted structure 9
2.2.7 Fabric Quality 11
2.2.8 Parameters that effect to quality of the fabric 11
v
2.3 Introduction to elastane yam 13
2.3.1 Characteristics of elastane fibre 14
2.3.2 New developments in elastane yam 15
2.4 Introduction to Nylon filament yam 15
2.4.1 Tensile properties of Nylon 6.6 16
2.4.2 Thermal properties of Nylon 6.6 17
2.5 Research review 18
Chapter 3: Methodology 25
3.1 Methodology 25
3.2 Preparation of Materials 25
3.2.1 Yam Details 25
3.2.2 Sample preparation 25
3.2.3 Testing of greige and finished samples 27
Chapter 4: Results and discussion 30
4.1 Analysis of the properties of greige fabric samples 30
4.1.1 Courses and wales densities of greige fabric samples 30
4.1.2 Stretchability of the greige fabric samples in length direction 32
4.1.3 Stretchabilityof greige fabric samples in width direction 35
4.2 Analysis of the properties of finished fabric 38
4.2.1 Courses and wales density of finished fabric samples 38
4.2.2 Stretchability of finished fabric samples in length direction 39
4.2.3 Stretchability of finished fabric samples in width direction 41
Chapter 5: Conclusion and recommendation 43
5.1 Conclusions 43
vi
5.2 Recommendation 44
Reference list 45
Appendix 49
Appendix 1 .a - Data collected to investigate the dimensional properties of the greige 
and finishedfabrics- Fabric weight in g/ m2 and courses and wales density 49
Appendix 1 .b - Data collected to investigate the stretchability of the fabric before and 
after finishing process- length and width direction of the fabric 52
vii
LIST OF FIGURES
Page
Figure 2.1 
Figure 2.2 
Figure 2.3 
Figure 2.4 
Figure 2.5 
Figure 2.6 
Figure 2.7 
Figure 2.8 
Figure 3.1
Warp knitted structure
weft knitted structure
Shogging and swing action of a guide bar
Formation ofopen(a) and closed(b) lap
Locknit loop structure
Chemical structure of Lycra polymer
Formation of Nylon 6.6
Effect of temperature on the tensile properties of Nylon 6.6 
Sample preparation method for test method ASTM-D3776 
Mass per unit area
Sample preparation method for test method LTD 3-Stretch 
and recovery test
Load at 20% extension of greige fabrics and run-in ratios 
Length direction
Load at different extensions of greige fabrics-Length direction 
Load at 20% extension of greige fabrics Width direction 
Load at different extensions of greige fabrics and run-in ratios 
Width direction
Load at 20% extension of finished fabrics Length direction 
Load at different extensions of finished fabrics 
Length direction
Load at 20% extension of finished fabric - width direction
5
6
7
8
9
14
16
18
28
Figure 3.2
29
Figure 4.1
34
Figure 4.2 
Figure 4.3 
Figure 4.4
35
38
38
Figure 4.5 
Figure 4.6
40
41
Figure 4.7 42
vi n
I
LIST OF TABLES
Page
Table 2.1 Properties of fabrics which are having closed & open loops 
Main tensile properties of Nylon 6.6 
Values for the yield strain and elastic recovery of Nylon 6.6 
Thermal properties of Nylon 6.6 at zero relative humidity 
Details of the yarn used for knitting the fabric samples 
Details of the Machineused for knitting the fabric samples 
Coding method of Greige fabrics
Courses & wales density of fabrics-Nylon 1400mm & 1330mm
Courses & wales density of fabrics- elastane Run-in 550mm
Load at 20% extension of the greige fabric samples
Length direction - Nylon Run-in 1400mm
Load at 20% extension of the greige fabric samples
Length direction - Nylon Run-in 1330mm
Load at 20% extension of the greige fabric samples Length
direction - elastane Run-in 550mm
Load at 20% extension of the greige fabric samples
width direction Nylon Run-in 1400mm
Load at 20% extension of the greige fabric samples
width direction Nylon Run-in 1330mm
Load at 20% extension of the greige fabric samples
width direction elastane Run-in 550mm
Courses and wales density of and finished fabric samples
Load at 20% extension of finished fabric samples
Length direction-Nylon Run-in 1400mmand 1330mm
Load at 20% extension of finished fabric samples
width direction
12
Table 2.2 17
Table 2.3 17
Table 2.4 18
Table 3.1 25
Table 3.2 26
Table 3.3 26
Table 4.1 30
Table 4.2 31
Table 4.3
32
Table 4.4
33
Table 4.5
34
Table 4.6
35
Table 4.7
36
Table 4.8
37
Table 4.9 39
Table 4.10
39
Table 4.11
41
IX
LIST OF ABBREVIATIONS
ABBREVIATION DESCRIPTION
% Percentage
Degree of Temperature
C Centigrade
F Franhide
ASTM American standard of textile material
bg Back guide bar
CPI Courses per Inch
GSM Gram per square meter
g/m2 Gram per square meter
f Front guide barg
K Tightness factor value
LTD -03 Limited brand stretch & recovery test 
Stitch Length/
/f Stitch Length-front guide bar
h Stitch Length - back guide bar/
S Stitch density
WPI Wales per inch
CPI Courses per inch
T Yarn count in Tex
Tf Yarn count in Tex - front guide bar
Yarn count in Tex - back guide barTb
SLS Sri-Lanka standard
x
;
TiG Sample which is having Run in ratio 2.5:1(1400:550) - Greige 
Sample which is having Run in ratio 2.8:1(1400:485)- Greige 
Sample which is having Run in ratio 2.3:1(1330:580)- Greige 
Sample which is having Run in ratio 2.4:1(1330:550)- Greige 
Sample which is having Run in ratio 2.5:1(1400:550) - Finish 
Sample which is having Run in ratio 2.8:1(1400:485)- Finish 
Sample which is having Run in ratio 2.3:1(1330:580)- Finish 
Sample which is having Run in ratio 2.4:1(1330:550)- Finish 
Greige Sample - Width Direction
T2G
t3g
t4g
TiF
T2F
t3f
t4f
Ge
Gl Greige Sample - Length Direction
Fe Finished Sample - Width Direction
Fl Finished Sample - Length Direction
xi
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