43—THE AIR-FLOW DIAMETER OF WOOL TOPS: THE EFFECT OF COEFFICIENT OF VARIATION

Differences between the results obtained for the fineness of wool tops measured by air-flow and projection-microscope methods can arise because the coefficient of variation of the measured top is different from that of the tops used to calibrate the air-flow meter. The validity of some assumptions implicit in the air-flow calibration is examined and a correction table for precise use of the air-flow meter calculated. The corrections range from ?2% at 16 μm to zero at 36μm.     

38—THE EFFECT OF FIBRE ARRANGEMENT ON THE INDICATION OF THE AIR-FLOW APPARATUS FOR WOOL FINENESS

The air-flow fineness apparatus, long used in the measurement of the fibre diameter of wool tops, is finding a rapidly growing application in the determination of the fineness of samples of loose wool or corings. It is known that the indication of the instrument is sensitive to the arrangement of fibres in the plug and that a calibration made by using wools in the form of tops cannot be expected to hold for the same wools in a different form.

This paper reports an investigation into the shift in instrument indication produced by subjecting tops to a variety of treatments: cutting, coring, hand- and machine-washing, and passage through the Shirley Analyser. The treatments were applied singly or in certain combinations. In all cases, the treatment produced an apparent increase in mean fibre diameter, i.e., increased air-permeability, the magnitude of the increase rising with mean diameter. The change in apparent diameter is considered to arise from an increase in pore-size distribution in the fibre mass, which is the result of disordering the fibre arrangement. Disordering can be caused by various treatments.

The effect of a steaming treatment on tops was somewhat similar to that produced by the other treatments already mentioned.

The magnitude of the apparent shift in diameter is tabulated for the important cases.     

18—THE EFFECT OF HUMIDITY ON THE PHOTOTENDERING OF UNDYED FIBRES

Various undyed textile fibres exposed to the Light-fastness Tester under different humidity conditions are shown to lose tensile strength to different degrees; poly(vinyl alcohol) fibre, viscose, nylon, and cotton are found to be very sensitive to changes in humidity, whereas Orion acrylic fibre and Terylene polyester fibre are the least sensitive materials among those tested.     

41—THE MEASUREMENT OF THE MEAN FIBRE DIAMETER OF WOOL SAMPLES BY LIQUID-SCINTILLATION SPECTROMETRY

In wool samples labelled uniformly with ¹⁴C, there is a good correlation between the mean fibre diameter and the proportion of β-radiation absorbed within the fibres. An account is given in this paper of the calibration of a method of measuring the mean fibre diameter, based on this principle, by applying it to a set of eight standard wool tops with known mean diameters. Subsequent tests with 23 other tops showed that the mean fibre diameter of small samples (75–100 mg) could be determined with good precision, the mean 95 % confidence limits for a single measurement on one test specimen being ±0–36 μm.

A test of the sampling and uniformity of the standard tops showed that similar results, within currently accepted limits, were obtained when test specimens (75 mg) were taken from any of ten randomly chosen positions along each top.     

33—A GRAVIMETRIC TECHNIQUE FOR DETERMINING THE MEAN FIBRE DIAMETER OF WOOL

A method is presented for determining the diameter of wool gravimetrically by using fibre snippets instead of full-length fibres. A quantity of the snippets is weighed and then counted with an electronic particle-size analyser (a Coulter Counter). The average length of snippets is obtained by measuring the length of a small random sample. The product of the average snippet length and the number of snippets present in the weighed sample provides an estimate of the total length of the weighed snippets. Hence their mass per unit length can be calculated, and, if the fibre density is known, the r.m.s. diameter can also be determined.

For continuous-filament nylon, the method gives excellent agreement with diameter values obtained by a conventional gravimetric technique. For combed wool, the snippet gravimetric diameter is always less than the projection-microscope diameter, corrected to r.m.s. Some of this difference is attributed to reentries in the wool-fibre surface.     

30—THE INFLUENCE OF ORIGIN ON THE STRESS–STRAIN RELATIONS OF WOOL FIBRES

Stress–Strain data for wool fibres of different origin are presented, the tests having been made under different moisture conditions. Small differences exist between wool fibres from primary and secondary follicles from the same animal, the secondary being easier to stretch both initially and finally under wet conditions. However, the relative yield slope is markedly higher for secondary than for primary fibres. Differences exist between and within breeds in the initial modulus, the stress at 15% extension, and the slopes of the curves in the yield and post-yield regions.     

31—COMPARISONS OF MICROPROJECTION AND AIR-FLOW DIAMETER MEASUREMENTS FOR SCOURED WOOL

A comparison is reported of fineness results obtained for 27 lots of scoured wool by the projection-microscope and air-flow methods. The sampling of the scoured wool was done by core-boring, and the cores were hand-carded before air-flow tests were made. The sub-samples for projection-microscope measurement were cut into snippets 1 mm long in order to obtain a length-biassed sample. The air-flow apparatus was calibrated with reference tops in five different forms. The results show that there exists a systematic difference between the air-flow and projection-microscope mean diameters of scoured wool when the air-flow instrument is calibrated with reference tops in the original state. A better agreement results by hand-carding the test samples of the reference tops, but the closest agreement is obtained by cutting, washing, and hand-carding these test samples so that their condition is similar to that of the core sample being tested. Provided that this kind of calibration were applied, the mean diameter of washed wool could be determined by air-flow testing of cored and hand-carded samples.     

56—THE WRINKLING BEHAVIOUR OF WOOL FABRICS: THE EFFECT OF THE STRUCTURE OF FORMALDEHYDE CONDENSATION POLYMERS ON THE STABILIZATION OF ANNEALED WOOL

An investigation is reported of the use of formaldehyde condensation polymers of aromatic amines, heterocyclic amines, and phenols to stabilize the improved wrinkle-recovery of annealed wool. These polymers were formed in situ during the annealing process.

The most effective polymer networks were those obtained from the reaction of formaldehyde with multifunctional compounds such as (i) 2,4,6-triaminopyrimidine, (ii) 2,6-diaminopyridine, (iii) 3,5-diamino-1,2,4-triazole, (iv) 1,3,5-trihydroxybenzene, (v) 1,3-dihydroxybenzene, and (vi) 2,4,6-triamino-s-triazine.     

16—THE CRIMP OF WOOL FIBRES AT VARIOUS REGAINS

The crimp parameters of merino-wool fibres, i.e., the uncrimping energy and stress, decrease with an increase in relative humidity from 5.14 × 10³ g cm/cm³ and 0.149 × 10⁶ g/cm² at 0% r.h. to 0.37 × 10³ g cm/cm³ and 0.021 × 10⁶ g/cm² at 100% r.h., i.e., decreases of 93 and 86%, respectively.

The decrease in the uncrimping parameters is linearly related to the increase in the ‘bound’ or ‘localized’ water up to the solution region of the wool-water isotherm. In the solution region, the crimp parameters appear to be associated with the ‘loose’ water.

It is suggested that the contribution of the matrix phase of the fibre (crimp A) to the over-all crimp decreases with an increase in relative humidity until in water the main crimp is related to the microfibrillar phase (crimp B).

The value of the drying uncrimping stress measured in this study, i.e., 1.25 × 10⁸ dyn/cm² is close to the value of 1.63 × 10⁸ dyn/cm² obtained previously for the ‘hygrostress’ at zero elongation, which indicates a parallelism between the two phenomena.     

42—THE EFFECT OF DEAGEING ON SOME MECHANICAL PROPERTIES OF WOOL OUTERWEAR FABRICS

This paper describes an experimental investigation of fabric-wrinkling behaviour as measured on a Thermobench, fabric stress-relaxation measured under both constant and varying ambient conditions, and inter-fibre friction of a series of three wool fabrics tested in both their ‘aged’ and ‘deaged’ states. Deaging of these fabrics was achieved by four different methods. It is shown that simply soaking in water at room temperature is an effective and practical deageing procedure for wool fabrics.     

6—THE EFFECT OF ALKALINE AND ACID SWELLING AGENTS ON THE MECHANICAL PROPERTIES OF COTTON FIBRES

A study of the changes in mechanical properties of cotton brought about by sodium hydroxide, an iron tartrate complex in caustic soda (EWNN), cuprammonium hydroxide, and sulphuric, phosphoric, nitric, and perchloric acids has been made. Instead of choosing the normal mercerizing conditions with sodium hydroxide, different temperatures of treatment and of washing were studied to see what effect the condition had on the subsequent mechanical properties of the fibres. The variable studied with the other reagents was that of concentration, so that a distinction between interfibrillar and intrafibrillar swelling could be made. The main effect of swelling is to alter the extensibility of the fibre, and this has been analysed at different stages of loading up to break.     

35—TORSIONAL STUDIES OF WOOL FIBRES

Studies of the torsional properties of single fibres of Rambouillet 70s-quality, Rambouillet × Chokla 58s-quality, and Chokla 48s-quality wools are reported. The torsional rigidity of wool fibres is found to be proportional to the 3.8th power of the diameter. The rigidity modulus decreases with increasing fibre diameter. This variation of the modulus is explained as being due to variation of the structural components with breed type and diameter. Anisotropy of the fibre material and the fullness of yarns spun from the wools examined are discussed.     

24—THE EFFECT OF FIBRE PROPERTIES AND WEAVE CRIMP ON THE HYGRAL EXPANSION OF WOVEN WOOL FABRICS

A study is reported in which 53 plain-weave and 55 twill-weave fabrics were produced under nominally identical conditions from different wool lots ranging greatly in fibre properties. The hygral expansion of these fabrics was measured and related to the various fibre properties and weave crimp.

It was found that fabric geometry, as reflected in weave crimp, was the most important factor contributing to hygral expansion, higher weave crimp leading to higher hygral expansion. Weave crimp also increased with an increase in staple crimp, as did hygial expansion, the effect of staple crimp being largely due to its effect on weave crimp.

Results obtained on the 108 all-wool fabrics and on six mohair fabrics produced under identical conditions to the all-wool fabrics indicated that weave crimp rather than fibre properties per se plays the main rôle in determining hygral expansion.     

35—AN AIR-FLOW PROCEDURE FOR DETERMINING THE FINENESS OF RAW WOOL

A satisfactory procedure has been found for determining with an air-flow meter the mean fineness of greasy wool sampled from bales by pressure-coring. A wool-model Shirley Analyser is used to remove dirt and vegetable matter from the washed wool cores. The Analyser also intimately mixes the wool fibres of a sample, which substantially improves the precision of the air-flow measurement. The effect of the Analyser on the measured value of fineness is investigated, and possible methods of calibration of the air-flow meter for use on wool cores are considered. A series of measurements on greasy-wool cores by both air-flow and projection-microscope methods is used as a basis for the suggested procedure. The precision of measurement is evaluated, and a particular calibration method is recommended. The mean fineness of a sample of greasy wool in core form can be found with a precision of ± 0 5 μm.     

23—STUDIES OF THE SULPHTTOLYSIS OF WOOL FIBRES PREVIOUSLY TREATED WITH IONIC SURFACTANTS

A study is reported in which wool fibres were pre-treated with ionic surfactants and subsequently subjected to sulphitolysis at different pH values in order to follow the chemical behaviour of cystine disulphide bonds in relation to that of bisulphite ions when surfactant molecules had previously been fixed on the protein. The influence of several parameters, such as the pH, concentration, temperature, and time of treatment of wool fibres with ionic surfactants, on the cystine reactivity was studied. Investigations of how treatment with alkylsulphates in the chain-length range C₆–C₁₆ modifies the reactivity of the native protein to sodium bisulphite are also reported.     

41—SOME EFFECTS OF THE SORPTION OF CATIONIC SURFACTANTS BY WOOL

Analytical methods developed for determining cationic surfactants in solution and in wool are described. These methods were used to study the sorption of representative cationic surfactants on wool and the stability of these finishes to rinsing. The effects of these sorbed surfactants on dyeing and as insectproofing treatments for wool were examined.     

10—THE WRINKLING BEHAVIOUR OF WOOL FABRICS: THE EFFECT OF ANNEALING AND CROSS-LINKING

An investigation is described in which various polyfunctional compounds were applied to wool in attempts to stabilize the temporary improvements in wrinkle-recovery brought about by ‘annealing’. Several reactive systems involving formaldehyde were found to produce the desired permanently improved wrinkle-recovery.     

37—THE AIR-FLOW FINENESS OF GREASY WOOL: INTER-LABORATORY TESTS OF A PROPOSED STANDARD PROCEDURE

An account is given of an inter-laboratory trial of a method of measuring the fineness of greasy wool by means of a Wira Air-flow Fineness Meter. Eight laboratories took part in two tasks: firstly, a calibration by each laboratory of its own air-flow meter in terms of internationally standardized wools; and, secondly, the measurement of the fineness of greasy-wool core samples by means of the specified method, which included a normal laboratory washing of the wool followed by opening on a wool-type Shirley Analyser.

As a result of the trial, the method was considered to be suitable for use by testing authorities, and tentative limits of precision of the method of measuring the fineness of greasy wool were established. The mean difference between any two laboratories ranged from 0.2 μm at 20-μm diameter to 0.5 μm at 28-μm diameter. This does not include sampling errors.     

3—AN EXPERIMENTAL INVESTIGATION OF THE PREDICTED SELECTION OF FIBRES BY THE NOBLE COMB

An account is given of a method developed for numerical evaluation of equations for predicting the distribution of fibres between the small and large circles on the Noble comb and the amount of noil removed in terms of the comb-settings and the holding power of the circles. Experiments are described that were made to test quantitatively the predicted behaviour of the comb for changes in feed, large-circle drawing-off-roller distance, and holding power, and, in general, good agreement is shown between the calculated and observed results.     

27—A STUDY OF THE REMOVAL OF VEGETABLE MATTER BY BURR BEATERS ON MODERN WORSTED CARDS

An investigation is reported in which the efficiency of burr beaters on a modern worsted card was measured over a range of vegetable-matter (VM) types and contamination levels. The results indicate the prime importance of the morels for removing VM from wool. Over-all, the burr beaters removed some 90% of the VM originally present, thicker particles being removed more efficiently than thinner ones. In an extension of the investigation, the efficiency of the comb was measured and found to be high and independent of particle size. This suggests that an increase in the working efficiency of the burr beaters during carding can lead to a reduction in the VM-contamination level of the final top.