TEXTILE HANDBOOK
CONTENTS 1 AN INTRODUCTION TO FIBRE STRUCTURE 1 1 1 GENERAL INTRODUCTION 1 1 2 METHODS OF INVESTIGATION OF STRUCTURE 4 1 3 APPROACHES TO POLYMER FIBRE STRUCTURE 21 1 4 CELLULOSE FIBRES 33 1 5 REGENERATED AND MODIFIED CELLULOSES 43 1 6 PROTEIN FIBRES 48 1 7 SYNTHETIC FIBRES FOR GENERAL USE 57 1 8 HIGH PERFORMANCE FIBRES 68 1 9 SPECIALIST FIBRES 75 1 10 SOME CONCLUDING VIEWS 77 1 11 REFERENCES 78 2 TESTING AND SAMPLING 82 2 1 TEST PROCEDURES 82 2 2 VARIABILITY AND SAMPLING 83 2 3 NUMERICAL AND BIASED SAMPLES 86 2 4 SAMPLING TECHNIQUES 90 2 5 ZONING 93 2 6 REFERENCES 95 3 FIBRE FINENESS AND TRANSVERSE DIMENSIONS 97 3 1 FIBRE DIMENSIONS 97 3 2 TERMS AND DEFINITIONS 99 3 3 THE TECHNICAL SIGNIFICANCE OF FIBRE FINENESS 103 3 4 VARIATION IN FINENESS 105 3 5 MEASUREMENT OF LINEAR DENSITY 107 3 6 DIRECT MEASUREMENT OF TRANSVERSE DIMENSIONS 109 3 7 OPTICAL TECHNOLOGY FOR HIGH SPEED TESTING 111 3 8 AIR FLOW METHODS 115 3 9 THE VIBROSCOPE METHOD 122 3 10 FIBRE SHAPE AND COTTON MATURITY 123 3 11 REFERENCES 131 4 FIBRE LENGTH 134 4 1 FIBRE LENGTHS 134 4 2 TECHNICAL SIGNIFICANCE OF FIBRE LENGTH 136 4 3 LENGTH DISTRIBUTIONS AND FIBRE DIAGRAMS 137 4 4 WOOL AND COTTON 144 4 5 CRIMP 146 4 6 INDIVIDUAL FIBRE LENGTH MEASUREMENT 147 4 7 COMB SORTER METHODS 149 4 8 THE BALLS SLEDGE SORTER 152 4 9 CUTTING AND WEIGHING METHODS 153 4 10 AUTOMATED SCANNING OF FIBRE TUFTS 156 4 11 SCANNING INDIVIDUAL FIBRES 161 4 12 REFERENCES 162 5 FIBRE DENSITY 163 5 1 INTRODUCTION 163 5 2 MEASUREMENT 163 5 3 RESULTS 165 5 4 DENSITY AND ORDER 165 5 5 REFERENCES 167 6 THERMAL PROPERTIES 168 6 1 INTRODUCTION 168 6 2 THERMAL PARAMETERS 168 6 3 REFERENCES 176 7 EQUILIBRIUM ABSORPTION OF WATER 178 7 1 INTRODUCTION 178 7 2 DEFINITIONS 178 7 3 MEASUREMENT OF REGAIN 180 7 4 RELATION BETWEEN REGAIN AND RELATIVE HUMIDITY 184 7 5 REFERENCES 193 8 HEATS OF SORPTION 195 8 1 DEFINITIONS 195 8 2 MEASUREMENT 196 8 3 RESULTS 198 8 4 EFFECTS OF EVOLUTION OF HEAT 201 8 5 REFERENCES 201 9 RATE OF ABSORPTION OF MOISTURE 202 9 1 INTRODUCTION 202 9 2 DIFFUSION OF MOISTURE 202 9 3 THE INTERACTION OF MOISTURE AND HEAT 212 9 4 PRACTICAL EFFECTS 223 9 5 REFERENCES 228 10 THE RETENTION OF LIQUID WATER 229 10 1 INTRODUCTION 229 10 2 CENTRIFUGING OF WET FIBRES 229 10 3 SUCTION 232 10 4 INTERACTIONS 235 10 5 REFERENCES 236 11 SWELLING 237 11 1 INTRODUCTION 237 11 2 MEASUREMENT OF SWELLING 238 11 3 RESULTS 240 11 4 REFERENCES 242 12 THEORIES OF MOISTURE SORPTION 243 12 1 THE GENERAL VIEW 243 12 2 QUANTITATIVE THEORIES OF ABSORPTION 251 12 3 THE RELATIONS BETWEEN ABSORPTION SWELLING AND ELASTIC PROPERTIES 261 12 4 SURFACE ADSORPTION 270 12 5 THE EFFECT OF TEMPERATURE 271 12 6 REFERENCES 272 13 TENSILE PROPERTIES 274 13 1 GENERAL INTRODUCTION 274 13 2 FACTORS DETERMINING THE RESULTS OF TENSILE EXPERIMENTS 274 13 3 EXPRESSING THE RESULTS QUANTITIES AND UNITS 276 13 4 EXPERIMENTAL METHODS 283 13 5 FIBRE PROPERTIES 289 13 6 OTHER FACTORS 309 13 7 REFERENCES 319 14 THE EFFECTS OF VARIABILITY 322 14 1 INTRODUCTION 322 14 2 VARIABILITY SPECIMEN LENGTH AND STRENGTH 322 14 3 VARIABILITY AND OTHER QUANTITIES 330 14 4 COMPOSITE SPECIMEN EFFECTS 332 14 5 VARIABILITY IN PRACTICE 335 14 6 CHANGES IN SPECIMEN DURING TEST 335 14 7 REFERENCES 337 15 ELASTIC RECOVERY 338 15 1 INTRODUCTION 338 15 2 DEFINITIONS 339 15 3 EXPERIMENTAL METHODS 340 15 4 RESULTS 341 15 5 CHANGE OF PROPERTIES AS A RESULT OF STRAINING MECHANICAL CONDITIONING 346 15 6 SWELLING RECOVERY 348 15 7 SIMPLE RECOVERY MODELS 349 15 8 REFERENCES 356 16 RHEOLOGY 357 16 1 THE STUDY OF TIME DEPENDENCE 357 16 2 CREEP 358 16 3 STRESS RELAXATION 370 16 4 TIME AND TENSILE TESTING 376 16 5 DYNAMIC TESTS 390 16 6 REFERENCES 411 17 DIRECTIONAL EFFECTS 414 17 1 INTRODUCTION 414 17 2 BENDING OF FIBRES 414 17 3 TWISTING OF FIBRES AND THE SHEAR MODULUS 430 17 4 SHEAR STRENGTH 440 17 5 GENERAL ELASTIC DEFORMATION 441 17 6 COMPRESSION STRESSES ON FIBRE MASSES 455 17 7 REFERENCES 455 18 THERMOMECHANICAL RESPONSES 458 18 1 INTRODUCTION 458 18 2 MELTING 462 18 3 DYNAMIC MECHANICAL RESPONSES 469 18 4 TRANSITIONS IN KERATIN FIBRES 478 18 5 THERMOMECHANICAL RESPONSES 483 18 6 SETTING 490 18 7 REFERENCES 506 1 1 GENERAL INTRODUCTION 1 1 1 THE NATURE OF MATTER FIBRE PHYSICS IS THE STUDY OF THE STRUCTURE AND PHYSICAL PROPERTIES OF FIBRES THESE TWO ASPECTS ARE NOT HOWEVER INDEPENDENT THE PROPERTIES MUST BE EXPLAINED BY THE STRUCTURE WHICH THEY ALSO HELP TO ELUCIDATE BECAUSE OF THIS CONNECTION IT IS APPROPRIATE TO START THIS BOOK ON THE PHYSICAL PROPERTIES OF FIBRES WITH A REVIEW OF WHAT IS KNOWN ABOUT THEIR STRUCTURE THERE IS MUCH DETAIL ONLY PARTLY SUPERSEDED BY MORE RECENT WORK IN THE BOOK EDITED BY HEARLE AND PETERS 1 AND THE REVIEW BY HEARLE AND GREER 2 OTHER INFORMATION IS IN THE GENERAL REFERENCES GIVEN AT THE END OF THE CHAPTER MATTER IS COMPOSED OF ATOMS LINKED TOGETHER BY BONDS OF VARYING STRENGTH IT IS THE ARRANGEMENT OF THESE ATOMS AND THE STRENGTH OF THE BONDS BETWEEN THEM THAT DETERMINE THE PHYSICAL PROPERTIES OF MATERIALS THUS WITH LIGHT ATOMS SUCH AS THOSE OF HELIUM ATTRACTED TO ONE ANOTHER BY VERY WEAK FORCES THE ENERGY OF THE ATOMS IS SUFFICIENT EXCEPT AT VERY LOW TEMPERATURES TO CAUSE THEM TO MOVE ABOUT INDEPENDENTLY AND THE MATERIAL IS A GAS THE MATERIAL WILL ALSO BE A GAS THOUGH WITH A HIGHER LIQUEFACTION POINT IF IT IS MADE UP OF HEAVIER ATOMS OR OF MOLECULES COMPOSED OF TWO OR THREE ATOMS HELD TOGETHER BY STRONG FORCES VALENCY BONDS PROVIDED THAT THE FORCES BETWEEN THE INDIVIDUAL MOLECULES ARE WEAK THESE WEAK FORCES ARE OFTEN CALLED VAN DER WAALS FORCES SINCE THEY ARE THE CAUSE OF ONE OF THE DEVIATIONS OF A REAL GAS FROM AN IDEAL GAS WHICH WERE CONSIDERED BY VAN DER WAALS IN HIS MODIFICATION OF THE GAS LAWS IF THE MOLECULES ARE HEAVY ENOUGH AND THE ATTRACTIVE FORCES STRONG ENOUGH THEN THE ATOMS WILL NOT HAVE SUFFICIENT ENERGY AT ROOM TEMPERATURE TO MOVE FREELY AWAY FROM ONE ANOTHER AND THE SUBSTANCE WILL BE A LIQUID OR A SOLID SOME MATERIALS ARE MADE UP OF GIANT MOLECULES FOR EXAMPLE IN A CRYSTAL OF DIAMOND ALL THE ATOMS ARE LINKED TO ONE ANOTHER BY VALENCY BONDS IN A REGULAR THREE DIMENSIONAL NETWORK THIS GIVES A VERY HARD NON FUSIBLE MATERIAL IN GRAPHITE WHICH IS ALSO PURE CARBON THE ATOMS ARE LINKED ONLY IN SINGLE PLANES BY VALENCY BONDS THE FORCES BETWEEN THE PLANES ARE WEAK SO THE MATERIAL IS ONE THAT EASILY SPLITS UP INTO SHEETS AND THESE WILL SLIDE OVER ONE ANOTHER GIVING A LUBRICATING ACTION IN LINEAR POLYMERS THE LINKING IS IN ONLY ONE DIMENSION IF THERE IS FLEXIBILITY IN THE MAIN CHAIN COVALENT BONDS AND ONLY WEAK BONDING BETWEEN THE LONG CHAIN MOLECULES THERE IS NOTHING TO PREVENT THERMAL ENERGY FROM CAUSING THE CHAINS TO TAKE UP A 1 AN INTRODUCTION TO FIBRE STRUCTURE 1