PROPERTIES O F C O R E SPUN A N D SPUN P O L Y E S T E R 
SEWING T H R E A D S A N D THEDM P E R F O R M A N C E IN S E A M S 
LIBRARY' •- -jn— vV 
K-PARAN A W I D AN A G E 6 
This thesis was submitted to the Department o f Texti le and Clothing 
Technology o f the University o f Moratuwa in partial fulf i lment o f the 
requirements for the Degree o f Master o f Science 
Department o f Textile and Clothing Technology 
University o f Moratuwa 
Sri Lanka 
May 2003 
U n i v e r s i t y o f M o r a t u w a 
UM Thesis Cell 
7 7 8 7 0 
77870 
The work presented in the thesis in part or whole, has not been submitted for 
any other academic qualification at any institution. 
K.Paranawidanage i Mr. D.P.D. Dissanayake 
(Candidate) (Supervisor) 
11 
A B S T R A C T 
At present number of sewing threads of different varieties are available in the market 
and there is no single polyester based substrate, which satisfies the criteria of the 
complete sewing thread. The thread must be able to withstand all of the stresses and 
strains applied to the thread during sewing and wear of the garment. Therefore 
selecting a proper thread to suite a particular fabric is very complex as it is important 
to minimize the sewing defects and improve the performance. 
The core spun and spun polyester sewing threads are having different thread 
structures, which contribute to significant changes in their properties. Largely because 
of its low price and acceptable level of sewing performance, 100% spun polyester 
sewing thread is the dominant product in sales volume. But the results of the research 
show that the core spun thread possesses superior properties to those of the other 
threads, which would provide an answer to the major sewing problems frequently 
occurring in the apparel industry. 
The core spun threads considered in this project are of two types, which are cotton 
wrapped and polyester wrapped core spun threads. When the thread is cotton wrapped 
it has very good needle heat resistance and polyester wrapped thread is excellent in 
physical properties and sewing performance. The fibrous surface of the core spun 
thread reduces shiny look and contributes to superior frictional characteristics. 
In today's competitive market, cost is an important factor. To reduce the thread cost of 
garments without sacrificing seam and sewing performance a better thread selection 
method is required. The findings of this research on the properties of core spun and 
spun polyester sewing threads and their performance in seam would provide an insight 
to many unresolved problems still facing the apparel industry-. 
111 
A C K N O W L E D G E M E N T 
The work presented in the thesis was carried out under the supervision of Mr. 
D.P.D. Dissanayake, Senior Lecturer of the Department and I wish to express my 
deepest gratitude for the advice & guidance during the course of the project. 
I am indebted to Dr. Nirmali de Silva, Head of the Department of Textile and 
Clothing Technology for giving me the opportunity to carry out this research 
project and for the kind cooperation extended for the successful completion of the 
research. 
I am much thankfull to Prof. Lakdas D. Fernando, former Head of the Department 
of Textile and Clothing Technology for the assistance given and Mr. N.L. 
Wanigathunga Senior Lecturer for being a member of the thesis committee and 
providing instructions to fulfill the requirements of the project. 
Further I wish to extend my gratefulness to the staff members of the department, 
who has helped me in various ways during the project period and my special 
thanks would be forwarded to the labotatory staff, Mrs. D. Dissanayake, Mrs. 
P.Wanniarachchi, G. Senevirathna and Mr. Chandradasa for their kind 
corporation. 
My sincere thanks would also be conveyed to Shadowline (Pvt) Ltd. and SR Gent 
(Pvt) Ltd. for providing me the fabrics and Textile Testing and Services Centre, 
Sri Lanka Standard Institution and Department of Textile and Apperal 
Technology, Open University of Sri Lanka for providing me some laboratory 
facilities. 
My sincere appreciation would be given to my friends Senaka, Udya, Pradeepa, 
Chamari, Gamini and my parents for supporting me in various ways for the 
completion of the research work. 
Finally I wish to express my gratitude to the Science and Technology 
Development Project of the Asian Development Bank for the financial assistance 
given to me in order to complete the Masters Degree by research. 
iv 
TABLES OF CONTENTS 
Page 
Abstract iii 
Acknowledgement iv 
Tables of Contents v 
List of Figures viii 
List of Tables x 
List of Annexes xi 
List of Abbreviations xii 
CHAPTER O N E 
INTRODUCTION 
1.1. Introduction 1 
1.2. Textile and Clothing Industry Sri Lanka 2 
1.3. Evolution of Sewing and Sewing Threads 5 
1.4. Properties of fibres commonly used in Sewing Threads 6 
1.4.1 Sewing Thread Types available 9 
1.4.1.1. Cotton Sewing Threads 9 
1.4.1.2. Silk and Linen Threads 10 
1.4.1.3. Polyester Sewing Threads 10 
1.4.1.3.1. Staple Spun Polyester Sewing Thread 10 
1.4.1.3.2. Monofilament Threads 10 
1.4.1.3.3. Multifilament Threads 11 
1.4.1.3.4. Textured Poly ester Threads 11 
1.4.1.3.5. Core Spun Threads 11 
1.4.1.4. Nylon Sewing Threads 12 
1.4.1.5. Other Threads 12 
1.5. Function and Properties of Sewing Threads 12 
1.5.1 Thread Price Vs Thread Sewing Cost 13 
1.6. Scope of the Project 15 
CHAPTER T W O 
0T MATERIALS & PROPERTIES OF THREADS & SEAMS 
2.1. Introduction 16 
2.2. Production of Threads 16 
2.2.1. Raw Materials 16 
2.2.1.1. Polyester Staple and Filament fiber 17 
2.2.1.2. Cotton fiber 17 
2.2.2. Production of Polyester and Core Spun Thread 17 
v 
ft* 
2.2.2.1. Fibre Opening 
2.2.2.2. Drawing and Reducing 
2.2.2.3. Drafting, Twisting and Yarn Formation 
2.2.2.4. Production of Sewing Threads 
(a). Polyester Spun Threads 
(b). Core Spun Threads 
2.3. Sewing Thread Parameters 
2.3.1. Linear Density and Ticket Number 
2.3.2. Twist of Single Yarn and Thread 
2.3.3. Tensile Properties 
2.3.3.1. Thread Breaking Strength and Extension 
2.3.3.2. Tenacity 
2.3.3.3. Work of Rupture 
2.3.3.4. Effect of Initial Modulus on sewing 
2.3.4. Irregularity or Unevenness 
2.3.5. Lubrication of Threads 
2.4. Properties of Threads with Respect to Seam Pucker 
2.5. Properties of Seam 
2.5.1. Seam Strength 
2.5.2. Seam Extension 
2.5.3. Seam Slippage 
CHAPTER THREE 
EXPERIMENTAL 
3.1. Test Sample and Test Procedures for Sewing Threads 
3.1.1. Linear Density 
3.1.2. Twist of Spun and Core Spun Thread 
3.1.3. Breaking Strength and Extension 
(a). Straight Breaking Strength and Extension 
(b). Loop Breaking Strength and Extension 
3.1.4. Irregularity 
3.1.5. Yarn to Metal Friction 
3.1.6. Lubricant Content 
3.2. Test Procedures for Fabric Properties 
3.2.1. Mass Per Unit Area 
3.2.2. Fabric Breaking Strength and Extension 
3.2.3. Fabric Thickness 
3.2.4. Bending Length 
3.3. Test Procedures and Sample Preparation to Test Seam Properties 
3.3.1. Preparation of Test Specimen 
3.3.2. Seam Strength, Seam Extension and Seam Slippage 
v i 
CHAPTER FOUR 
RESULTS & DISCUSSION 
4.1. Physical and Mechanical Properties of Thread 38 
4.1.1. Linear Density 38 
4.1.2. Twist ' 38 
4.1.3. Tensile Properties 39 
4.1.3.1. Breaking Strength and Extension 40 
4.1.3.2. Tenacity 42 
4.1.3.3. Work of Rupture 43 
4.1.3.4. Initial Modulus 44 
4.1.4. Frictional Characteristics and Lubricant Content 46 
4.1.4. Thread Irregularity 46 
4.2. Sewing Thread Pucker Index (STPI) 47 
4.3. Performance of Seams with Respect to Fabric Type and Thread Type 48 
4.3.1. Seams of Satin Brush Back Fabric 49 
4.3.1.1. Seam Strength 50 
4.3.1.2. Seam Extension 51 
4.3.1.3. Seam Slippage 52 
4.3.2. Performance of Seams of Polyester/Cotton Fabric 53 
4.3.1.1. Seam Strength 53 
4.3.1.2. Seam Extension 54 
4.3.1.3. Seam Slippage 55 
4.3.3. Performance of Seams of Denim Fabric 56 
4.3.1.1. Seam Strength 57 
4.3.1.2. Seam Extension 58 
CHAPTER FIVE 
Conclusions and Recommendations 6 0 
References 63 
Annex A 65 
Annex B 87 
Annex C 88 
vii 
List of Figures 
Figure No. Title 
1.1 Garment Export growth rate (on USD basis) 
1.2 Change of consumer value Equation 
1.3 Ancient Sewing Machine Needles 
1.4 Classification of Threads 
1.5 No of thread breaks per hour for single needle and double needle 
machine 
2.1. (a) Core Spun Thread 
2.1. (b) Spun Polyester Thread 
2.2 Stress-strain properties of cotton and polyester fibers 
2.3 Carding Machine 
2.4 Roller Drafting Arrangement 
2.5 Ring Spinning 
2.6 Two for One Twister 
2.7 Core yarn spinning action 
2.8 Direction of twist 
2.9 Twist Vs Strength curve 
2.10 Load-Elongation curve for thread 
2.11 STPI Vs Linear Density 
2.12 STPI Vs. Irregularity 
2.13 STPI Vs. Extension (%)at IN Load 
2.14 STPI Vs. Friction 
3.1 Preparation of Test Specimen 
4.1 Load-Elongation curves for three types of threads 
4.2 Straight Breaking Strength and Loop Breaking Strength with Thread 
Type 
4.3 Straight Breaking Extension and Loop Breaking Extension with Thread 
Type 
4.4 Straight Tenacity and Loop Tenacity against Thread Type 
4.5 The Graph of Specific Work of Rupture vs. Thread Type 
4.6 Initial Modulus with Thread Type 
4.7 Friction and Lubricant Content of Threads with Thread Type 
4.8 Thread Evenness for different Thread Types 
4.9 Seam Strength vs. Stitch Density for tkt.120 P/P, SP and 
C/P in warp direction for Satin fabric 
4.10 Seam Strength vs. Stitch Density for tkt. 120 P/P, SP and 
C/P in weft direction for Satin fabric 
4.1 1 Seam Strength vs. Stitch Density for tkt. 180 P/P, SP and 
C/P to warp direction for Satin fabric 
4.12 Seam Strength vs. Stitch Density for tkt. 180 P/P, SP and 
C/P in weft direction for Satin fabric 
4.13 Seam Extension vs. Stitch Density for tkt. 120 P/P, SP and 
C/P in warp direction for Satin fabric 
4.14 Seam Extension vs. Stitch Density for tkt.120 P/P, SP and 
C/P in weft direction for Satin fabric 
4.15 Seam Extension vs. Stitch Density for tkt. 180 P/P, SP and 
C/P in warp direction for Satin fabric 
4.16 Seam Extension vs. Stitch Density for tkt. 180 P/P. SP and 
V l l l 
C/P in weft direction for Satin fabric 
4.17 Seam Slippage vs. Stitch Density for tkt. 120 P/P, SP and 
C/P in warp direction for Satin fabric 
4.18 Seam Slippage vs. Stitch Density for tkt. 120 P/P, SP and 
C/P in weft direction for Satin fabric 
4.19 Seam Slippage vs. Stitch Density for tkt. 180 P/P, SP and 
C/P in warp direction for Satin fabric 
4.20 Seam Slippage vs. Stitch Density for tkt. 180 P/P, SP and 
C/P in weft direction for Satin fabric 
4.21 Seam Strength vs. Stitch Density for tkt. 120 P/P, SP and 
C/P in warp direction for Polyester/Cotton fabric 
4.22 Seam Strength vs. Stitch Density for tkt. 120 P/P, SP and 
C/P in weft direction for Polyester/Cotton fabric 
4.23 Seam Strength vs. Stitch Density for tkt. 180 P/P, SP and 
C/P in warp direction for Polyester/Cotton fabric 
4.24 Seam Strength vs. Stitch Density for tkt. 180 P/P, SP and 
C/P in weft direction for Polyester/Cotton fabric 
4.25 Seam Extension vs. Stitch Density for tkt. 120 P/P, SP and 
C/P in warp direction for Polyester/Cotton fabric 
4.26 Seam Extension vs. Stitch Density for tkt. 120 P/P, SP and 
C/P in weft direction for Polyester/Cotton fabric 
4.27 Seam Extension vs. Stitch Density for tkt. 180 P/P, SP and 
C/P in warp direction for Polyester/Cotton fabric 
4.28 Seam Extension vs. Stitch Density for tkt. 180 P/P, SP and 
C/P in weft direction for Polyester/Cotton fabric 
4.29 Seam Slippage vs. Stitch Density for tkt. 120 P/P, SP and 
C/P in warp direction for Polyester/Cotton fabric 
4.30 Seam Slippage vs. Stitch Density for tkt. 120 P/P, SP and 
C/P in weft direction for Polyester/Cotton fabric 
4.31 Seam Slippage vs. Stitch Density for tkt. 180 P/P, SP and 
C/P in warp direction for Polyester/Cotton fabric 
4.32 Seam Slippage vs. Stitch Density for tkt. 180 P/P, SP and 
C/P in weft direction for Polyester/Cotton fabric 
4.33 Seam Strength vs. Stitch Density for tkt. 120 P/P, SP and 
C/P in warp direction for Denim fabric 
4.34 Seam Strength vs. Stitch Density for tkt. 120 P/P, SP and 
C/P in weft direction for Denim fabric 
4.35 Seam Strength vs. Stitch Density for tkt. 180 P/P, SP and 
C/P in warp direction for Denim fabric 
4.36 Seam Strength vs. Stitch Density for tkt. 180 P/P, SP and 
C/P in weft direction for Denim fabric 
4.37 Seam Extension vs. Stitch Density for tkt. 120 P/P, SP and 
C/P in warp direction for Denim fabric 
4.38 Seam Extension vs. Stitch Density for tkt. 120 P/P, SP and 
C/P in weft direction for Denim fabric 
4.39 Seam Extension vs. Stitch Density for tkt. 180 P/P, SP and 
C/P in warp direction for Denim fabric 
4.40 Seam Extension vs. Stitch Density for tkt. 180 P/P, SP and 
C/P in weft direction for satin fabric 
IX 
List of Tables 
Table No. Title 
1.1 The number of enterprises by size 
1.2 Properties of fibres commonly used in sewing threads 
1.3 Properties of Cotton and Polyester sewing threads 
1.4 Results of number of thread break per hour for single needle and 
double needle machines 
3.1 Sewing Thread Types and Ticket Number 
3.2 Needle, thread and fabric weight relationship 
4.1 Linear Density of sewing Threads 
4.2 Twist of Sewing Threads 
4.3 Results of Thread Breaking Strength and Breaking Extension 
4.4 Results of Thread Loop Strength and Loop Extension 
4.5 Results of Straight Tenacity and Loop Tenacity 
4.6 Results of Work of Rupture and Specific Work of Rupture 
4.7 Results of Initial Modulus of threads 
4.8 Results of yarn to metal friction and lubricant content of threads 
4.9 Results of thread Irregularity 
4.10 Sewing Thread Pucker Index values for threads 
4.11 Structural properties of fabrics. 
List of Annexes 
Annex Title 
A Physical Properties of Sewing Threads 
B Properties of Fabrics 
C Seam Properties 
r 
x i 
Abbreviations 
MFA - Multi-fibre Arrangement 
USA - United State of America 
EU - European Union 
TQM - Total Quality Management 
UNIDO - United Nations Industrial Development Organization 
P/P - Polyester Wrapped Polyester Core Spun Thread 
C/P - Cotton Wrapped Polyester Core Spun Thread 
SP - 100% Spun Polyester Thread 
ISO - International Standard Organisation 
Tkt - Ticket Number 
Fig -Figure 
120/75 - Needle thread tkt. 120/ Bobbin Thread tkt 75 
xii