PHYSICAL PROPERTIES OF TEXTILE FIBRES

By SARAH MILLER

CONTENTS AN INTRODUCTION TO FIBRE STRUCTURE GENERAL INTRODUCTION METHODS OF INVESTIGATION OF STRUCTURE APPROACHES TO POLYMER FIBRE STRUCTURE CELLULOSE FIBRES REGENERATED AND MODIFIED CELLULOSES PROTEIN FIBRES SYNTHETIC FIBRES FOR GENERAL USE HIGH-PERFORMANCE FIBRES SPECIALIST FIBRES SOME CONCLUDING VIEWS REFERENCES TESTING AND SAMPLING TEST PROCEDURES VARIABILITY AND SAMPLING NUMERICAL AND BIASED SAMPLES SAMPLING TECHNIQUES ZONING FIBRE FINENESS AND TRANSVERSE DIMENSIONS FIBRE DIMENSIONS TERMS AND DEFINITIONS THE TECHNICAL SIGNIFICANCE OF FIBRE FINENESS VARIATION IN FINENESS MEASUREMENT OF LINEAR DENSITY DIRECT MEASUREMENT OF TRANSVERSE DIMENSIONS OPTICAL TECHNOLOGY FOR HIGH-SPEED TESTING AIR-FLOW METHODS THE VIBROSCOPE METHOD FIBRE SHAPE AND COTTON MATURITY FIBRE LENGTH FIBRE LENGTHS TECHNICAL SIGNIFICANCE OF FIBRE LENGTH LENGTH DISTRIBUTIONS AND FIBRE DIAGRAMS WOOL AND COTTON CRIMP INDIVIDUAL FIBRE LENGTH MEASUREMENT COMB-SORTER METHODS THE BALLS SLEDGE SORTER CUTTING-AND-WEIGHING METHODS AUTOMATED SCANNING OF FIBRE TUFTS SCANNING INDIVIDUAL FIBRES FIBRE DENSITY INTRODUCTION MEASUREMENT RESULTS DENSITY AND ORDER THERMAL PROPERTIES THERMAL PARAMETERS EQUILIBRIUM ABSORPTION OF WATER DEFINITIONS MEASUREMENT OF REGAIN RELATION BETWEEN REGAIN AND RELATIVE HUMIDITY HEATS OF SORPTION EFFECTS OF EVOLUTION OF HEAT RATE OF ABSORPTION OF MOISTURE DIFFUSION OF MOISTURE THE INTERACTION OF MOISTURE AND HEAT PRACTICAL EFFECTS THE RETENTION OF LIQUID WATER CENTRIFUGING OF WET FIBRES SUCTION INTERACTIONS SWELLING MEASUREMENT OF SWELLING THEORIES OF MOISTURE SORPTION THE GENERAL VIEW QUANTITATIVE THEORIES OF ABSORPTION THE RELATIONS BETWEEN ABSORPTION, SWELLING AND ELASTIC PROPERTIES SURFACE ADSORPTION THE EFFECT OF TEMPERATURE TENSILE PROPERTIES FACTORS DETERMINING THE RESULTS OF TENSILE EXPERIMENTS EXPRESSING THE RESULTS: QUANTITIES AND UNITS EXPERIMENTAL METHODS FIBRE PROPERTIES OTHER FACTORS THE EFFECTS OF VARIABILITY VARIABILITY, SPECIMEN LENGTH AND STRENGTH VARIABILITY AND OTHER QUANTITIES COMPOSITE-SPECIMEN EFFECTS VARIABILITY IN PRACTICE CHANGES IN SPECIMEN DURING TEST ELASTIC RECOVERY CHANGE OF PROPERTIES AS A RESULT OF STRAINING: MECHANICAL CONDITIONING SWELLING RECOVERY SIMPLE RECOVERY MODELS RHEOLOGY THE STUDY OF TIME DEPENDENCE CREEP STRESS RELAXATION TIME AND TENSILE TESTING DYNAMIC TESTS DIRECTIONAL EFFECTS BENDING OF FIBRES TWISTING OF FIBRES AND THE SHEAR MODULUS SHEAR STRENGTH GENERAL ELASTIC DEFORMATION COMPRESSION STRESSES ON FIBRE MASSES THERMOMECHANICAL RESPONSES MELTING DYNAMIC MECHANICAL RESPONSES TRANSITIONS IN KERATIN FIBRES SETTING FIBRE BREAKAGE AND FATIGUE FIBRE-FRACTURE MORPHOLOGY MONOTONIC BREAKS TENSILE FATIGUE TORSIONAL FATIGUE FLEX FATIGUE COMBINED BENDING AND TWISTING: BIAXIAL ROTATION SURFACE WEAR AND PEELING ABRASION AND WEAR THEORIES OF MECHANICAL PROPERTIES STRUCTURAL EFFECTS IN RAYON FIBRES NYLON, POLYESTER AND SIMILAR FIBRES A GENERAL THEORY OF ORIENTATION STRUCTURAL EFFECTS IN NATURAL FIBRES THEORIES OF TIME DEPENDENCE THERMODYNAMIC EFFECTS DIELECTRIC PROPERTIES DEFINITIONS OF DIELECTRIC PROPERTIES THE EFFECT OF FREQUENCY THE EFFECT OF MOISTURE THE EFFECT OF OTHER FACTORS SUMMARY OF RESULTS FOR VARIOUS MATERIALS ELECTRICAL RESISTANCE METHODS OF MEASUREMENT RESULTS OF EXPERIMENTS THEORETICAL STATIC ELECTRICITY MEASUREMENT OF STATIC GENERATION OF CHARGE LEAKAGE OF CHARGE OPTICAL PROPERTIES REFRACTION ABSORPTION AND DICHROISM REFLECTION AND LUSTRE FIBRE FRICTION MEASUREMENT OF FIBRE FRICTION EMPIRICAL RESULTS THE NATURE OF FRICTION THE FRICTION OF WOOL 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