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.     

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.     

19—THE MEASUREMENT OF TORQUE IN CONTINUOUS-FILAMENT YARNS. PART II: THE EFFECT OF YARN TENSION

The yarn torque developed by the applied tension in the torsion-balance apparatus described in Part 1 of this series is calculated by using an expression derived in an earlier paper. Differences in shape of net-torque–twist curves are studied for nylon monofilaments and model plied yarns; these differences in shape are related to friction effects and to the mechanical properties of the constituent filaments. The torsional rigidity of the yarns is evaluated from the initial slope of the torque–twist curves for a series of nylon monofilaments; the torsional rigidity and torsional modulus are also calculated from the load–extension curve of a closely wound helical spring by employing the classical theory of elasticity.     

44—THE CONTRIBUTION OF THE BILATERAL STRUCTURE OF WOOL TO HYGRAL EXPANSION

Measurements are reported of the hygral expansion of yarns extracted from permanently set fabrics made from merino and Lincoln wools. For yarns having similar crimp, the hygral expansion of merino-wool yarn is much greater than that of Lincoln-wool yarn. The values in both cases agree with predictions based on single-fibre behaviour. It seems certain that this difference is caused by the presence of a consistent bilateral structure in merino wool, which is absent from Lincoln wool.     

24—THE BENDING BEHAVIOUR OF PLAIN-WEAVE FABRICS WOVEN FROM SPUN YARNS

The bending behaviour of square plain-weave fabrics spun and woven from nineteen different fibres, each in a range of cover factors, has been studied. It is shown how this behaviour is determined by the mechanical properties of the fibre and the frictional and geometrical restraints within and between yams in the fabric. The effects on these restraints of cover factor and of relaxation in wet finishing and in heat-setting are examined. Factors affecting cloth stiffness are summarized, and it is shown that two quantities, an elastic component and a frictional component, are required to specify the bending behaviour with reasonable completeness.     

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.     

32—A SIMPLIFIED METHOD OF DETERMINING THE LENGTH AND FINENESS CHARACTERISTICS OF FIBRES IN JUTE SLIVERS AND YARNS

The normal method of studying the length and fineness characteristics of fibres in jute slivers and yarns involves classifying the fibres in a sample into a suitable number of length groups and determination of the frequency and linear density of fibres in all the length groups. The simplified method described in this paper requires evaluation of the cumulative frequency and linear density of fibres of one particular length only, and is hence less time-consuming than the normal method. Graphical relations and tables are provided with the simplified method to reduce the computation time, which is considerable with the normal method. The data obtained on several yarn samples of different qualities by the normal method of testing are used to show the agreement between the results arrived at by the two methods. A procedure for carrying out the tests required in the simplified method is also suggested.     

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.     

42—THE ESTIMATION OF CROSS-LINKS IN WOOL FROM THE EXTENT OF SWELLING IN FORMIC ACID

An account is given of the application of a gravimetric method for measuring the extent of swelling of wool in formic acid to a series of wool samples containing decreasing amounts of randomly distributed disulphide bonds. In accordance with the Flory-Rehner equation, a linear relation was observed between disulphide content and V 5/3, where V is the volume of dry wool expressed as a fraction of the volume of swollen wool. This calibration curve was then used in conjunction with swelling data to assess the number of cross-links introduced on the treatment of wool with formaldehyde and other bifunctional reagents. The method is particularly useful for ranking in order relatively high levels of cross-linking.     

50—SOME ASPECTS OF WORSTED-YARN STRUCTURE. PART III: THE FIBRE-PACKING DENSITY IN THE CROSS-SECTION OF SOME WORSTED YARNS

Measurement of the fibre-packing density in the cross-section of a range of wool worsted yarns indicates that these are slightly hollow at the core, with the maximum packing density occurring about one-quarter of the yarn radius from the yarn axis. A comparison of these results with those obtained on cotton-viscose rayon yarns by other workers is also made.     

23—THE SETTING OF KNITTED WOOL FABRICS IN THE EXTENDED STATE

Setting treatments known to be effective for woven wool fabrics were applied to pure-wool weft-knitted fabrics while they were held in the extended state. The fabrics, of plain, interlock, and bourrelet structures, were initially wet-relaxed and conditioned before treatment. The effectiveness of the treatments was assessed by steam- and wet-relaxation techniques. For the plain fabrics, even the most successful treatments were not capable of preventing most of the set from being lost during a single mild wash. On the other hand, about half the set imparted lo the double-jersey fabrics could be retained under the same conditions. A possible explanation for this difference is advanced, this being based upon the difference in the setting behaviour of fibres in torsion and in bending.     

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.     

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.     

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.     

9—THE VALIDITY OF PRESSURE-CORING FOR ESTIMATION OF THE CONTENT OF BURR MEDIC IN WOOL BALES

Miniature wool bales of about normal packing density (approximately 16 lb/ft³ on a greasy-wool basis) were constructed from burr-free greasy wool with burr added in such a way that the true over-all burr content was known. These were sampled with a range of pressure-coring tools differing in size. Except when small coring tools were used in bales of high burr content, there was no significant difference between the mean burr content of several core samples from a miniature bale and the true over-all value for that bale. It is concluded that the act of pressure-coring does not distort the burr content of a sample and that the sample is therefore suitable for determination of clean-wool content. The between-core variance of burr content decreases as the size of coring tool increases.     

10—THE VALIDITY OF PRESSURE-CORING FOR ESTIMATION OF THE CONTENT OF NOOGOORA BURR IN WOOL BALES

Experiments are described to establish the validity of samples, for Noogoora-burr determination, taken from wool bales with pressure-coring tools. Coring tools of ¾-in. and larger diameters give unbiassed samples for the determination of both Noogoora burr and burr medic. The ½-in.-diameter tool, although previously shown to give unbiassed samples for the determination of burr medic, is subject to some bias in the sampling of bales containing Noogoora burr.     

35—THE ACTION OF SODIUM LAURYLSULPHATE IN THE BLEACHING OF WOOL WITH HYDROGEN PEROXIDE IN AN ACIDIC MEDIUM

A study is reported of the influence of a sodium laurylsulphate treatment, at different pH values, on the properties of wools bleached with hydrogen peroxide in an acidic medium with Prestogen W used as stabilizer. It is shown that the pretreatment at different pH values gives whiter wools but a lower content of cysteic acid and greater alkali-solubility than untreated wool under the same conditions. Bleaching wool m a hydrogen peroxide bath containing sodium laurylsulphate in an acidic medium and using Prestogen W gives rather similar variations, although these are more perceptible than those derived from the application of a pretreatment with sodium laurylsulphate and a post-bleaching treatment.     

17—THE PREDICTION OF THE COMMERCIAL CARBONIZING YIELD OF WOOL

An investigation is reported in which the core-test yield was compared with the achieved mill yield for 90 commercial batches of Australian wool. Eight Australian mills participated in the trial. It was found that the wool base of the greasy wool (B _g%) was directly proportional to the achieved mill yield. The carbonizing loss, which was on the average 3.05% (on an oven-dry basis), was negatively correlated with the vegetable-matter base of the greasy wool (VMB _g%. The most precise prediction of the achieved mill yield was given by the equation:

ECCY% = 1.1972 B _g% + 0.1616 VMB _g% ? 5.12,

where ECCY% is the estimated commercial carbonizing yield. For the 90 batches in the trial, the standard error of the prediction was 1.95%.     

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.