STUDIES ON THE INFLUENCE OF SOME RAW MATERIAL AND OTHER PARAMETERS ON THE STRUCTURE AND PROPERTIES OF AIR-JET TEXTURED YARNS by R. S. RENGASAMY Department of Textile Technology submitted in fulfilment of the requirements of the Degree of DOCTOR OF PHILOSOPHY to the INDIAN INSTITUTE OF TECHNOLOGY, DELHI March, 1990
CERTIFICATE This is to certify that the thesis entitled 'Studies on the Influence of Some Raw Material and Other Parameters on the Structure and Properties of Air-jet Textured Yarns' submitted by Mr. R.S. Rengasamy to the Indian Institute of Technology, Delhi, for the award of Degree of Doctor of Philosophy is a record of the bonafide research work carried out by Mr. R.S. Rengasamy. He has worked under our guidance for the submission of this thesis, which to our knowledge has reached the requisite standard. This thesis or any part thereof, has not been submitted to any other University or Institution for the award of any degree or diploma. (A.K. Sengupta) (V.K. Kothari) Professor Asstt. Professor Thesis Supervisors Department of Textile Technology Indian Institute of Technology, Delhi New Delhi-110 016.
ACKNOWLEDGEMENTS I wish to put on record my deep sense of gratitude to Prof. A.K. Sengupta and Dr. V.K. Kothari of Department of Textile Technology, Indian Institute of Technology, Delh:, for their invaluable guidance and constant involvement throughout the course of this work. It is due to their tireless supervision that this work has developed into its present form- I thank Prof. V.B.. Gupta, Dr. P.K. Banerje,.2. and Dr. Kushal Sen for their kind help in times of need. My thanks are also to my friends and research colleagues especially, Mr. J. Srinivasan, Mr. R. Alagirusamy Mr. R.B. Joshi, Mr. R. Anandakumar, Mr. C. Brahatheeswaran, Mr. K. Mohan, Mr. K.R. Srinivasan and Dr. T. Murugesan who at times relieved my stress by their help and moral support. I am very greateful to Spinning Laboratory Technicians Mr. R.S. Ojha, Mr. J.K. Dang for their co-operation. I thank Mr. Rajesh K. Arora for typing this thesis so quickly and Mr. K.G. Padam and Mr. R.P. Kapoor for their neat tracing of figures both for the thesis and for publications. (R.S. Rengasamy)
Dedicated to My Parents
ABSTRACT In the air-jet texturing process, the action of fluid forces causes the filaments of continuous filament yarns to separate, forces them to form loops of various configurations and to entangle. The form and frequency of loops are expected to influence the appearance and properties of fabrics made with the air-jet textured yarns. Many methods of analysis of the structure and measurement of the more important properties of these yarns such as instability and bulk have been reported, without agreement regarding the suitability of these methods. This has led to differences in the interpretation of the texturing behaviour. A method of analysing the structure of air--jet textured yarns is described. This method is used t ) quantify the structural parameters such as configuration of loops, loop frequency, average loop height and length, and core diameter. The various methods of assessing the instability of air-jet textured yarns are evaluated as regards their suitability. It is found that the instability values measured by all the methods have a good correlation with texturability. However, the measure of instability based on the extension values of the yarns is dependent on parent yarn extension properties and hence cannot be used for comparing the stability of textured yarns made usinc; parent yarns of different filament extensibilities The instability test method, based on percentage decay in the
work done after a fixed number of repeated loading cycles, which is not influenced by the extension properties of parent yarns and also simulates the deformation pattern of the yarns during processing and while in fabric form, is, therefore, recommended. To evaluate the bulkiness of airjet textured yarns, the methods reported in the literature to assess the bulk, and also the relationship between the physical bulk measured Oy the package density method and structural parameters such as core diameter and loop frequency are studied. The static and dynamic wicking behaviour of air-jet textured yarns are examined in terms of the structure and filament properties. Water plays 3n important role in air-j-t texturing. Wetting of the supply yarns before entering the texturing jet, is known to improve texturability. Changes in the fluid properties inside the jet and a reduction in the friction of filaments during texturing are the explanations put forward by various research workers. To study the influence of water, polyester yarns of different friction levels and nylon yarns conditioned in environments of different relative humidities have been textured in both dry and wet conditions. A test rig was fabricated to measure the interfilament friction. The tensions generated at the nozzle exit and in stabilizing the structure, the instability, bulk, mass uniformity and tensile properties of air-jet textured yarns have also been studied in relation to the frictional levels ii
of the filaments. Friction influences the structure and properties of air-jet textured yarns. A deterioration in air-jet textured yarn quality has been observed at higher levels of interfilament friction. It has been found that the role of interfilament friction is same within dry and wet textured yarns. Discrepancies between the structures of dry and wet textured yarns and yarn properties are observed when they are analysed in terms of Friction levels of feeder yarns during texturing. The results suggest that the role of water is not related to frictional aspects alone. The analysis of the influence of filament parameters on the structure and properties of air-jet textured yarn is important in understanding the interaction between the filaments and fluid forces during the process. Filament parameters such as filament fineness, cross-sectional shape and the number of filaments in the yarn have been studied in relation to their influence on structure and properties. A high level of dependence has been observed. Texturability of yarns with 'aeavier filaments is poor in terms of loop frequency, loop height and length, loop shape and yarn bulk. Yarns with trilobal filaments perform better in air-jet texturing compared to yarns with circular filaments of similar fineness. There is an optimum number of ends for good stability of textured yarns using a particular jet. Mass uniformity, tensile strength realisation and bulk levels of air-jet textured yarns tend to improve with an increasing number of ends. iii
The air-jet texturing process provides an effective means of blending yarns with filaments of different chemical natures and properties. As the appearance of fabrics is influenced by the blend uniformity of the constituent threads, an understanding of the role of the various parameters of air-jet texturing in influencing blend uniformity is important, so that the required degree of blend intimacy in the air-jet textured yarns may be engineered. Blend inhomogeneity is quantitatively assessed in relation to raw material and nozzle parameters etc. Blend uniformity is poor in the case of blends of components of dissimilar properties. Blend homogeneity improves with the degree of texturing as assessed by the delivery zone tension. In the case of components of similar properties, finer filaments are found to produce better blend homogeneity. iv
Page No. CONTENTS CHAPTER 1 : INTRODUCTION AND GENERAL REVIEW 1.1 1.2 Introduction Classification of Textured Yarns and Texturing Methods 1 2 1.2.1 Classification of textured yarns 2 1.2.2 Classification of texturing methods 3 1.3 Air-jet Texturing 5 1.3.1 Air-jet texturing process 6 1.3,2 Mechanism of bulking in air-jet texturing 9 1.3.3 Developments in air-jet texturing 12 1.3.3.1 Industrial nozzles developments 14 1.3.3.2 Wetting devices 24 1.3.3.3 Developments in air-jet texturing machines 25 1.3.4 Types of air-jet textured yarns 27 1.3.5 Properties of air-jet textured yarns 29 1.3.6 Variables in air-jet texturing process 30 1.3.7 Range of feeder yarns and end-products 31 1.3.8 Production speeds and future projections 32 1.4 Air-jet Texturing as an Alternative to False- Twist Texturing and Spun Yarn Methods 33 1.4.1 Air-jet texturing vs. false-twist texturing 33 1.4.2 Air-jet texturing vs. spun yarn methods 36 1.5 Objectives of the Present Study 38
CHAPTER 2 : REVIEW OF LITERATURE PERTAINING TO THE PRESENT WORK 2.1 Structure and Properties of Air-jet Textured Yarns 40 2.1.1 Structure of air-jet textured yarns 41 2.1.2 Methods of analysing structure of air-jet textured yarns 42 2.1.3 Measurement of instability of air-jet textured yarns 43 2.1.4 Bulkiness of air-jet textured yarns 48 2.2 Frictional Behaviour of Textile Fibres 50 2.2.1 General mechanism of friction 50 2.2.2 Friction of high polymers 51 2.2.3 Friction and lubrication of synthetic fibres 53 2.2.4 Parameters influencing frictional behaviour 55 2.2.4.1 Chemical structure of lubricants 56 2.2.4.2 Input tension 58 2.2.4.3 Surface roughness 58 2.2.4.4 Speed and viscosity 59 2.2.4.5 Area of contact 59 2.2.4.6 Temperature of guide or fibre 60 2.2.4.7 Lubricant concentration 60 2.2.4.8 Fibre lustre 61 2.2.5 Fibre material and wetting of fibres 61 2.3 Role of Water in Air-jet Texturing 63 2.3.1 Role of water in changing the fluid properties 65 ii
2.3.2 Role of water as a lubricant for hydrophobic fibres 65 2.3.3 Effect of wetting on textured yarn properties 67 2.3.4 Spin finishes, frictional behaviour and wetting 68 2.3.5 Relative humidity and air-jet texturing of hydrophilic fibres 69 2.4 Raw Material and Jet Parameters in Air-jet Texturing 70 2.4.1 Interaction of fluid and filaments in air-jet texturing 70 2.4.2 Effect of filament properties on properties of air-jet textured yarns 72 2.4.3 Effect of jet parameters 74 2.4.3.1 Converging-diverging nozzles 74 2.4.3.2 Cylindrical nozzles 77 2.4.4 Effect of impact elements 80 2.5 Blend Intimacy in Air-jet Textured Yarns 80 2.5.1 Quantitative Analysis of Blend Inhomogeneity 81 CHAPTER 3 : EVALUATION OF STRUCTURE AND PROPERTIES OF AIR-JET TEXTURED YARNS 3.0 Introduction 83 3.1 Experimental 83 3.1.1 Structural geometry of air-jet textured yarns 83 3.1.2 Evaluation of methods for measuring instability 85 3.1.2.1 Materials 3.1.2.2 Tension measurements at the nozzle exit and at the stabilizing zone 86
3.1.2.3 Methods of measuring instability 86 3.1.3 Evaluation of Bulkiness of air-jet textured yarns 89 3.1.3.1 Package density method 90 3.1.3.2 Fabric thickness method 91 3.1.3.3 Water uptake method 91 3.1.3.4 Structural analysis as a possible measure of bulk 92 3.1.4 Measurement of Wicking Properties 92 3.2 Results and Discussion 93 3.2.1 Structure of air-jet textured yarns 93 3.2.2 Evaluation of structural stability of air-jet textured yarns 95 3.2. Evaluation of bulkiness of air-jet textured Yarns 120 3.2.4 Wicking properties of air-jet textured yarns 131 3.2.4.1 Equilibrium wicking behaviour 131 3.2.4.2 Dynamic wicking behaviour 143 3.3 Summary 143 CHAPTER 4 : ROLE OF WATER IN AIR-JET TEXTURING 4.0 Introduction 147 4.1 Role of Water ink Air-jet Texturing of Polyester Filam nt Yarns 148 4.1.1 Experimental 148 4.1.1.1 Materials 148 4.1.1.2 Spin finish application 149 4.1.1.3 Measurement of interfilament friction 149 4.1.1.4 Test methods 154 i v
4.1.2 Results and Discussion 155 4.2 Role of Conditioning Environment and Water in Air-jet Texturing of Nylon Yarns 179 4.2.1 Experimental 179 4.2.1.1 Conditioning of feeder yarns 179 4.2.1.1 Test methods 182 4.2.2 Results and Discussion 182 4.3 Summary 207 CHAPTER 5 : EFFECT OF RAW MATERIAL CHARACTERISTICS ON STRUCTURE AND PROPERTIES OF AIR-JET TEXTURED YARNS 5.0 Introduction ' 209 5.1 Experimental 209 5.2 Results and Discussion 212 5.2.1 Effect of filament fineness (dpf) 212 5.2.2 Effect of filament cross-sectional shape 240 5.2.3 Effect of number of filaments 252 5.3 Summary 255 CHAPTER 6 : BLEND INHOMOGENEITY IN AIR-JET TEXTURED YARNS 6.0 Introduction 257 6.1 Experimental 258 6.1.1 Materials 258 6.1.2 Process parameters 258 6.1.3 Nozzles 258 6.1.4 Free filament yarn speed measurement 262 6.1.5 Preparation and examination of yarn cross-sections 263
6.1.6 Computational method 264 6.1.7 Tension measurements 266 6.2 Results and Discussion 266 6.3 Summary 287 CHAPTER 7 : CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE WORK 7.1 Conclusicns- 289 7.2 Recommendations for Future Work 293 REFERENCES 295 LIST OF PUBLICATIONS vi