10—THE DIMENSIONAL PROPERTIES OF SOME WOOL DOUBLE-JERSEY STRUCTURES IN RELAXATION AND LAUNDERING

The dimensional behaviour of five non-jacquard wool double-jersey structures is investigated, both in relaxation (involving tumble-drying from the wet state) and in extensive laundering (Cubex washing followed by tumble-drying).

Tumble-drying for 1 hr from the wet-fabric condition only approximates to the completely relaxed state. Some felting of untreated fabrics occurs, but the effect of tumble-drying on felting is very small. Adequately shrink-resist-treated fabrics cannot be considered completely relaxed even after two consecutive tumble-drying cycles of 1-hr duration. However, in general, this technique allows sufficient fabric relaxation for subsequent dimensional changes over extensive laundering cycles of treated fabrics to be compatible with domestic machine-washable tolerances.

The felting rates of knitted wool fabrics in laundering from the ‘fully relaxed’ condition of untreated fabrics are dependent on the cover factor and independent of fabric structure. Under no circumstances, however, can untreated double-jersey fabric be practically manufactured to such tight constructions that felting can be eliminated entirely.

The linear dimensions of shrink-resist-treated fabrics in the fully laundered state are primarily dependent on the length of yarn in the structural knitted cell. In a semi-relaxed state, linear dimensions depend to a large extent on cover factor and the degree of distortion of the fabric.     

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.     

6—DIMENSIONAL STABILITY OF PLAIN-KNITTED FABRICS

An account is given of a study of the dimensional changes of plain-knitted fabrics brought about by various relaxation treatments. A wide range of natural and synthetic-polymer fibres was encompassed.

It was found that, for synthetic-fibre fabrics, dry tumbling at elevated temperatures causes higher levels of relaxation shrinkage and larger changes in shape than static wet-relaxation treatments, whereas the opposite is true of fabrics produced from hydrophilic fibres. A wet treatment at an elevated temperature is proposed that brings about complete relaxation of all the fabrics investigated. It is only in this completely relaxed state that the loop shape is similar for all the fabrics investigated.     

2—HYGRAL CHANGES IN CURVATURE AND LENGTH IN SET KERATINS

The set developed in various wools and hairs when strained in boiling water or in monoethanolamine sulphite (MEAS) has been measured, together with the longitudinal swelling of set fibres on wetting. The changes in curvature of merino fibres on wetting are enhanced by setting in boiling water or in cold MEAS but diminished by setting in boiling 1% MEAS. The interpretation of these changes of curvature in terms of ortho–para differences throws into question the supposition that there is a specific para-type keratin (exemplified by human hair) and a specific ortho-type keratin (kid mohair). Some technological treatments diminish the hygral changes in curvature.     

25—THE WRINKLING OF WOOL WORSTED FABRICS. PART I: FIBRE AND YARN DEFORMATION IN BENDING

Experiments are described in which the extensional, bending, and twisting strains of seven fibres were measured in a wool worsted fabric deformed in a multiple-pleat tester. The only significant strain appeared to be the bending strain.     

34—THE CONTROL OF THE SHAPE AND DIMENSIONS OF KNITTED WOOL FABRICS

An account is given of an investigation of the use of steam treatments as a means of controlling the shape and dimensions of plain-knitted wool fabrics, firstly by allowing the fabric to relax towards its dimensionally stable state during steaming and secondly by steam-setting the fabric while it is held at a predetermined width. This steam-setting procedure is compared with two permanent-setting treatments for wool—a chemical-setting treatment and setting in boiling water.

Of the two methods of producing a dimensionally stable fabric, namely, by relaxation and by setting, the relaxation method is by far the more effective. The most important result of this work is that knitted wool fabrics—whether unset, steam-set, or permanently set—will always approach their completely relaxed shape and dimensions after only a couple of minutes' gentle agitation in water. It is concluded that conventional methods of shaping knitted wool fabrics and garments, which rely principally on steam-setting the fabric or garment to a size and shape different from its relaxed size and shape, are not likely to produce garments that have good dimensional stability and good shape-retention properties.

The ineffectiveness of permanent-setting agents in producing dimensionally stable knitted garments is contrasted with the relative effectiveness of these agents in producing pleats and permanent creases in wool cloths. This difference in behaviour is explained in terms of the different levels of individual fibre strains involved.     

18—TIME-DEPENDENT RECOVERY AND RELAXATION EFFECTS IN RESIN-TREATED COTTON FABRICS

Results are presented for the crease-recovery of resin-treated Oxford-weave fabrics after various loading and recovery times. Results are also given for the bending couple-relaxation and tensile stress-relaxation of these fabrics. It is shown that the differences between the crease-recoveries of moist-cure-treated and pad–dry-cure-treated fabrics may be attributed, at least in part, to the time-insensitivity of the former. It is also shown that the relaxation rates obtained by bending and extending a fabric sample are broadly similar within a reasonable range of either curvature or extension. An explanation is offered for some differences in behaviour.     

26—THE WRINKLING OF WOOL WORSTED FABRICS. PART II: BENDING SET IN SINGLE FIBRES AND FABRIC AND THE EFFECT OF AGEING

An account is given of an investigation in which the recovery from bending of isolated wool fibres subjected to strains similar to those found in a wool fabric during bending in the multiple-pleat tester was measured. Fabric recovery and fibre recovery differ by a small amount that is probably produced by friction hindering relative movement. The improvement of fabric recovery with ageing is shown to be a single-fibre property, the friction being apparently unchanged.     

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.     

57—THE DEGREE AND STABILITY OF FLAT-SET IN WOVEN COTTON FABRICS

The determination of Fabric flat-setting by measurement of the bending recovery at low and medium curvatures, before and after wet treatment, is discussed. The degree, stability, and rating of flat-set obtained by the use of a Shirley bending-hysteresis Tester are described. Comparisons are made with visual assessments based on fabric replicates and with other objective assessments, such as crease-recovery.     

7—THE RÔLE OF EXTERNAL POLYMERS IN IMPROVING THE WRINKLE-RECOVERY OF WOOL FABRICS

Stress-relaxation curves of a worsted fabric in bending, obtained under changing humidity and temperature conditions, are compared with those obtained from the same fabric treated with an elastic silicone polymer used to impart improved wrinkle-resistance. From an analysis of these curves, it is shown that the strain levels occurring in the polymer when the treated fabric is bent are two orders of magnitude higher than the strain levels occurring in the wool. From these and other data, it is concluded that the polymer improved the wrinkle-recovery of wool fabrics by providing elastic connexions between fibres. These act firstly by considerably reducing the frictional restraint impeding recovery and secondly by providing an additional elastic restoring force, which does not stress-relax and is unaffected by temperature and humidity changes. This additional elastic restoring force arises from energy stored in shear deformations in the polymer.     

44—THE WRINKLE-RECOVERY OF CARRIER-DYED WOOL–POLYESTER-FIBRE FABRICS

An investigation is described in which the reduction in wrinkle-recovery of wool–polyester-fibre fabrics caused by the use of carrier during dyeing was studied. Only the polyester-fibre component absorbed appreciable amounts of carrier, and the extent of the reduction in wrinkle-recovery depended on the type and amount of carrier retained in the polyester fibre after dyeing. The effectiveness of finishing treatments in removing carrier and restoring wrinkle-recovery is discussed in terms of changes in the glass-transition temperature.     

30—HEAT AND MOISTURE EXCHANGE IN WOOL BEDS: EQUILIBRIUM THEORY IN THE HYGROSCOPIC RANGE

Cassie's theory of propagation of heat and moisture changes in beds of wool fibres is re-examined by means of the method of characteristics. Substantial differences result in the predictions of the theory by treating the coefficients of the pertinent differential equations as functions of the dependent variables rather than as constants.     

12—RESIDUAL GREASE IN THE GILLING AND RECTILINEAR COMBING OF MERINO WOOL

In gilling and combing, there is an optimum level of residual grease, which gives a top with the lowest percentage noil and the highest mean fibre length. It is shown that, if the residual grease of the scoured wool could be held at approximately 0.8%, there would be little to be gained by the addition of a combing oil.     

15—EXPERIMENTAL STUDIES OF THE DIMENSIONAL PROPERTIES OF EYELET FABRICS. PART I: THE DIMENSIONAL PROPERTIES OF CLOSE-EYELET COTTON FABRICS

The geometrical parameters of the eyelet structure are related to its loop length in both the dry- and the wet-relaxed states. The effects of the structural characteristics of the stitch on its dimensional properties are discussed. Formulae relating the weight per square yard and weight per running yard to the loop length are given and confirmed experimentally.     

6—STAPLE-LENGTH VARIATION IN GREASY WOOL

Estimates are reported for the variance of staple length within bales for each of 33 bales taken from separate sale lots of skirted classed merino wool. These variances range from 0.59 to 2.90 cm², with an average of 1.53 cm². Variances between bales, within sale lots of merino wool, were small and not significant. Within-bale variances for comeback and crossbred fleece ranged from 0.61 to 4.62 cm², with an average of 2.64 cm². The highest variances occurred within lots of broken and pieces, these ranging from 1.83 to 6.33, with an average of 3.44 cm².

Evidence is presented which suggests that the removal of short wool during skirting makes the largest contribution to staple-length uniformity, classing having a secondary effect. Of the variation occurring within a bale, about half is found within fleeces and half between fleeces.     

31—EXPERIMENTAL STUDIES OF THE DIMENSIONAL PROPERTIES OF DOUBLE-KNIT FABRICS

An investigation is reported in which the dimensional properties of some double-jersey structures are compared under conditions whereby the run-in ratio, average loop length, cylinder-and-dial loop length, or dial-only loop length is maintained constant. It is concluded that, on the basis of the average loop length, K values, from which other dimensional parameters can be calculated, may be used to characterize the structures under investigation.     

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.     

20—THE RELATIONSHIP BETWEEN QUALITY NUMBER IN WOOL AND FIBRE DIAMETER WITHIN CLIPS

This study provides evidence that a negative association exists between quality number and fibre diameter for fleeces grown in the same flock. The efficiency of classing by quality number, as a means of separating fleeces of different average fibre diameter, varies from flock to flock and may be influenced by such factors as the strain or breed of sheep, the nutritional level, the environment, and the age of sheep.