Physical Testing of Textiles by B P Saville

By

Physical Testing of Textiles
by B. P. Saville

Physical Testing of Textiles

Contents

Preface …………………………………………………………………. xiii
Acknowledgements ………………………………………………… xv 

1. Introduction ……………………………………………………. 1
1.1 Reasons for Textile Testing ………………………………… 1
1.1.1 Checking Raw Materials ……………………… 1
1.1.2 Monitoring Production ………………………… 2
1.1.3 Assessing the Final Product ………………… 2
1.1.4 Investigation of Faulty Material …………….. 2
1.1.5 Product Development and Research …….. 2
1.2 Standardization of Testing ………………………………….. 3
1.2.1 Variation in the Material ………………………. 3
1.2.2 Variation Caused by the Test Method ……. 3
1.3 Sampling ………………………………………………………….. 4
1.3.1 Terms Used in Sampling …………………….. 5
1.3.2 Fibre Sampling From Bulk …………………… 6
1.3.3 Fibre Sampling From Combed Slivers,
Rovings and Yarn ………………………………. 7
1.3.4 Yarn Sampling …………………………………… 11
1.3.5 Fabric Sampling ………………………………… 14
1.4 Measurement ……………………………………………………. 15
1.4.1 Statistical Terms ………………………………… 16
1.4.2 Determination of Number of Tests ………… 18
1.4.3 Use of Computers ……………………………… 18
1.4.4 Types of Error …………………………………… 20
1.4.5 Sources of Error ………………………………… 20
1.4.6 Repeatability and Reproducibility …………. 21
1.4.7 Significant Figures ……………………………… 23
General Reading ……………………………………………………….. 24
References ……………………………………………………………….. 25

2. Textiles and Moisture ……………………………………… 26
2.1 Introduction ……………………………………………………….. 26
2.2 Effect of Moisture on Physical Properties ……………… 26
2.2.1 Dimensional ……………………………………… 26
2.2.2 Mechanical ……………………………………….. 27
2.2.3 Electrical ………………………………………….. 28
2.3 Atmospheric Moisture ………………………………………… 29
2.3.1 Vapour Pressure ……………………………….. 30
2.3.2 Relative Humidity ………………………………. 31
2.3.3 Standard Atmosphere ………………………… 32
2.3.4 Measurement of Atmospheric Moisture …………… 32
2.4 Regain and Moisture Content ……………………………… 33
2.4.1 Regain – Humidity Relations of Textiles …………………. 33
2.4.2 Factors Affecting the Regain ……………….. 35
2.4.3 Methods of Measuring Regain ……………… 36
2.5 Correct Invoice Weight ……………………………………….. 40
2.6 Control of Testing Room Atmosphere ………………….. 42
References ……………………………………………………………….. 43

3. Fibre Dimensions ……………………………………………. 44
3.1 Fibre Fineness ………………………………………………….. 44
3.2 Fineness Measurement ……………………………………… 45
3.2.1 Gravimetric ……………………………………….. 46
3.2.2 Fibre Fineness by Projection Microscope ………. 48
3.2.3 Fibre Fineness by the Airflow Method …… 50
3.2.4 Cotton Fineness by Airflow ………………….. 52
3.2.5 Cotton Maturity ………………………………….. 53
3.2.6 IIC/Shirley Fineness and Maturity Tester ………. 55
3.2.7 Optical Fibre Diameter Analyzer …………… 56
3.2.8 Light-Scattering Methods ……………………. 56
3.2.9 Vibration Method ……………………………….. 57
3.2.10 Wool Quality ……………………………………… 59
3.3 Fibre Length ……………………………………………………… 59
3.3.1 Mean Length …………………………………….. 60
3.4 Methods of Measurement: Direct Methods …………… 62
3.4.1 WIRA Fibre Length Machine ……………….. 63
3.5 Methods of Measurement: Tuft Methods ………………. 64
3.5.1 Cotton Grading ………………………………….. 64
3.5.2 Comb Sorter ……………………………………… 65
3.5.3 The Clamped Tuft Method …………………… 67
3.5.4 Fibrograph ………………………………………… 69
3.5.5 WIRA Fibre Diagram Machine ……………… 69
3.5.6 Almeter …………………………………………….. 71
3.6 High-Volume Instruments …………………………………… 74
General Reading ……………………………………………………….. 75
References ……………………………………………………………….. 75

4. Yarn Tests ……………………………………………………… 77
4.1 Linear Density …………………………………………………… 77
4.1.1 Direct System ……………………………………. 77
4.1.2 Indirect System …………………………………. 78
4.1.3 Folded Yarns …………………………………….. 79
4.1.4 Measuring Linear Density ……………………. 80
4.1.5 Linear Density from a Fabric Sample ……. 82
4.2 Twist ………………………………………………………………… 85
4.2.1 Level of Twist ……………………………………. 87
4.2.2 Measuring Twist ………………………………… 89
4.3 Yarn Evenness ………………………………………………….. 94
4.3.1 Visual Examination …………………………….. 94
4.3.2 Cut and Weigh Methods ……………………… 94
4.3.3 Uster Evenness Tester ……………………….. 96
4.3.4 Zweigle G580 ……………………………………. 101
4.4 Hairiness ………………………………………………………….. 104
4.4.1 Shirley Yarn Hairiness Tester ………………. 106
4.4.2 Zweigle G565 ……………………………………. 107
4.4.3 Uster Tester 3 Hairiness Meter Attachment…… 108
4.5 Yarn Bulk ………………………………………………………….. 108
4.5.1 Textured Filament Yarns …………………….. 109
4.6 Friction ……………………………………………………………… 110
4.6.1 Coil Friction ………………………………………. 111
4.6.2 Measuring Yarn Friction ……………………… 112
References ……………………………………………………………….. 114

5. Strength And Elongation Tests ……………………….. 115
5.1 Introduction ……………………………………………………….. 115
5.2 Definitions …………………………………………………………. 115
5.2.1 Units ………………………………………………… 115
5.2.2 Breaking Strength; Tensile Strength ……… 116
5.2.3 Stress ………………………………………………. 116
5.2.4 Specific (Mass) Stress ………………………… 116
5.2.5 Tenacity …………………………………………… 117
5.2.6 Breaking Length ………………………………… 117
5.2.7 Elongation ………………………………………… 118
5.2.8 Strain ………………………………………………. 118
5.2.9 Extension Percentage ………………………… 118
5.2.10 Gauge Length …………………………………… 118
5.3 Force Elongation Curve ……………………………………… 118
5.3.1 Yield Point ………………………………………… 119
5.3.2 Modulus …………………………………………… 122
5.3.3 Work of Rupture ………………………………… 125
5.3.4 Time Dependence ……………………………… 127
5.3.5 Elastic Recovery ……………………………….. 129
5.4 Factors Affecting Tensile Testing ………………………… 132
5.4.1 Type of Testing Machine …………………….. 132
5.4.2 Specimen Length ………………………………. 134
5.4.3 Rate of Loading and Time to Break ………. 134
5.4.4 Effect of Humidity and Temperature ……… 135
5.4.5 Previous History of the Specimen …………. 136
5.4.6 Clamping Problems ……………………………. 136
5.5 Fibre Strength ……………………………………………………. 138
5.5.1 Single Fibre Strength ………………………….. 138
5.5.2 Bundle Strength ………………………………… 140
5.6 Yarn Strength ……………………………………………………. 142
5.6.1 Yarn Strength: Single Strand Method ……. 143
5.6.2 Yarn Strength: Skein Method ………………. 144
5.7 Fabric Strength ………………………………………………….. 145
5.7.1 Strip Strength ……………………………………. 145
5.7.2 Grab Test …………………………………………. 146
5.8 Tear Tests ………………………………………………………… 147
5.8.1 Measuring Tearing Strength ………………… 147
5.8.2 Single Rip Tear Test …………………………… 148
5.8.3 Wing Rip Tear Test ……………………………. 150
5.8.4 Elmendorf Tear Tester ……………………….. 152
5.9 Bursting Strength ………………………………………………. 154
5.9.1 Diaphragm Bursting Test …………………….. 154
5.9.2 Ball Bursting Strength …………………………. 156
5.10 Stretch and Recovery Properties …………………………. 156
5.11 Seam Strength ………………………………………………….. 160
5.11.1 Seam Slippage ………………………………….. 160
5.11.2 Seam Slippage Tests …………………………. 161
5.11.3 Fixed Load Method …………………………….. 162
5.11.4 Upholstery Seam Slippage ………………….. 164
General Reading ……………………………………………………….. 165
References ……………………………………………………………….. 166

6. Dimensional Stability ……………………………………… 168
6.1 Introduction ……………………………………………………….. 168
6.1.1 Hygral Expansion ………………………………. 169
6.1.2 Relaxation Shrinkage …………………………. 171
6.1.3 Swelling Shrinkage …………………………….. 172
6.1.4 Felting Shrinkage ………………………………. 173
6.1.5 Weft Knitted Wool Fabrics …………………… 174
6.2 Methods of Measuring Dimensional Stability ………… 174
6.2.1 Marking Out Samples …………………………. 174
6.2.2 WIRA Steaming Cylinder …………………….. 175
6.2.3 Relaxation Shrinkage …………………………. 177
6.2.4 Washable Wool …………………………………. 177
6.2.5 Washing Programmes ………………………… 180
6.2.6 Dimensional Stability to Dry Cleaning ……. 181
6.2.7 Dimensional Stability to Dry Heat …………. 181
General Reading ……………………………………………………….. 182
References ……………………………………………………………….. 182

7. Serviceability ………………………………………………….. 184
7.1 Introduction ……………………………………………………….. 184
7.2 Snagging ………………………………………………………….. 185
7.2.1 Mace Snagging Test ………………………….. 186
7.3 Pilling ……………………………………………………………….. 186
7.3.1 Pilling Tests ………………………………………. 190
7.4 Abrasion Resistance ………………………………………….. 195
7.4.1 Factors Affecting Abrasion Resistance ………….. 195
7.4.2 Abrasion Tests ………………………………….. 196
7.5 Wearer Trials …………………………………………………….. 204
7.5.1 Advantages of Wearer Trials ……………….. 204
7.5.2 Disadvantages of Wearer Trials …………… 205
7.5.3 Advantages of Laboratory Tests …………… 206
7.5.4 Disadvantages of Laboratory Tests ………. 206
7.5.5 Design of Trials …………………………………. 206
References ……………………………………………………………….. 207

8. Comfort ………………………………………………………….. 209
8.1 Introduction ……………………………………………………….. 209
8.2 Thermal Comfort ……………………………………………….. 209
8.2.1 Heat Balance …………………………………….. 209
8.2.2 Heat Loss …………………………………………. 210
8.2.3 Air Permeability …………………………………. 217
8.2.4 Measurement of Thermal Conductivity …………………. 219
8.2.5 Measurement of Water Vapour Permeability … 223
8.3 Moisture Transport …………………………………………….. 227
8.3.1 Wetting …………………………………………….. 228
8.3.2 Wicking ……………………………………………. 229
8.3.3 Longitudinal Wicking ………………………….. 230
8.3.4 Wicking Test ……………………………………… 230
8.3.5 Transverse Wicking ……………………………. 231
8.4 Sensorial Comfort ……………………………………………… 232
8.5 Water Absorption ………………………………………………. 233
8.5.1 Static Immersion ……………………………….. 233
8.5.2 Wettability of Textile Fabrics ……………….. 234
8.5.3 Sinking Time …………………………………….. 235
8.6 Water Repellency ………………………………………………. 235
8.6.1 Spray Rating …………………………………….. 236
8.6.2 Bundesmann Water Repellency Test ……. 236
8.6.3 WIRA Shower Test …………………………….. 239
8.6.4 Credit Rain Simulation Tester ………………. 241
8.6.5 Hydrostatic Head ……………………………….. 241
References ……………………………………………………………….. 242

9. Colour Fastness Testing …………………………………. 244
9.1 Introduction ……………………………………………………….. 244
9.1.1 Sample Preparation ……………………………. 246
9.2 Outline of Colour Fastness Tests ………………………… 246
9.2.1 Colour Fastness to Light …………………….. 246
9.2.2 Colour Fastness to Other Agents …………. 250
References ……………………………………………………………….. 255

10. Objective Evaluation of Fabric Handle …………….. 256
10.1 Handle ……………………………………………………………… 256
10.1.1 Bending Length …………………………………. 256
10.1.2 Shirley Stiffness Test ………………………….. 258
10.1.3 Hanging Loop Method ………………………… 259
10.1.4 Drape ………………………………………………. 260
10.1.5 Crease Recovery ………………………………. 262
10.1.6 Fabric Thickness ……………………………….. 265
10.1.7 Shear ………………………………………………. 267
10.1.8 Bias Extension ………………………………….. 272
10.1.9 Formability ……………………………………….. 274
10.1.10 Fabric Friction …………………………………… 275
10.2 Kawabata System ……………………………………………… 279
10.2.1 Subjective Assessment of Fabric Handle ……… 279
10.2.2 Objective Evaluation of Fabric Handle …. 282
10.3 FAST: Fabric Assurance by Simple Testing ………….. 288
10.3.1 Compression …………………………………….. 290
10.3.2 Bending Length …………………………………. 290
10.3.3 Extensibility ………………………………………. 292
10.3.4 Dimensional Stability ………………………….. 293
General Reading ……………………………………………………….. 294
References ……………………………………………………………….. 294

11. Quality …………………………………………………………… 296
11.1 Definitions of Quality ………………………………………….. 296
11.2 Types of Quality ………………………………………………… 297
11.3 Quality Control …………………………………………………… 298
11.4 Quality Assurance ……………………………………………… 298
11.5 ISO 9000 ………………………………………………………….. 298
11.5.1 Enquiries and Orders …………………………. 300
11.5.2 Purchased Material or Services ……………. 300
11.5.3 Inspection and Testing ……………………….. 300
11.5.4 Calibration of Test Equipment ……………… 301
11.5.5 Organizational Structure ……………………… 301
11.5.6 Quality Audit ……………………………………… 301
11.5.7 Training ……………………………………………. 301
11.6 Textile Product Labeling …………………………………….. 302
11.6.1 Fibre Content ……………………………………. 302
11.6.2 Flammability Labels ……………………………. 303
11.6.3 Origin Markings …………………………………. 305
11.6.4 Care Labeling ……………………………………. 305
References ……………………………………………………………….. 305
Appendix: Conversion Factors ……………………………… 306
Index ……………………………………………………………………. 307

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