21—THE ACETYLATION OF COTTON

An account is given of a study of the effect of the amount of activating agent, the temperature, the catalyst, and the diluents used in the acetylation of cotton with perchloric acid as catalyst. Sulphuric acid was compared with perchloric acid as a catalyst. The effects of traces of water, the amount of acetyl chloride, and the rate of acetylation were studied in the acetylation of cotton with acetyl chloride and pyridine. The conditions in all cases were such that the acetylated cotton retained its fibrous form.     

24—THE RELATIONS BETWEEN THE FIBRE-LENGTH PARAMETERS OBTAINED FROM THE DIGITAL FIBROGRAPH,THE COMB SORTER,AND THE SHIRLEY PHOTO-ELECTRIC STAPLER

An account is given of an investigation in which linear relations, with varying degrees of correlation, were found between the span length (S.L.) from the Digital Fibrograph and (a) the upper-half mean length, (b) the upper-quartile length, and (c) the mean fibre length, respectively, from the comb sorter, and between S.L. and the staple length determined on the Shirley Photo-electric Stapler. Correlations were dependent on the span amount in the S.L. and reached their optimum value for 30% S.L. and comb-sorter parameters, and for 2.5–10% S.L. and staple length from the Shirley Photo-electric Stapler.     

The Effect of Environment on the Flexural Rigidity of Woven Fabrics

The concept of fabric engineering—the design of fabrics with predetermined physical properties—is used in relation to the structure of woven fabrics, and it is shown from theoretical considerations, with the aid of computer analysis, that a large discrepancy exists between the number of weaves of comparatively small size that can be woven and the number that are actually produced. Experimental results obtained on fabrics woven in accordance with a particular plan indicate that the weave has a very marked effect on both tearing strength and stiffness. The results further suggest that weave modification can provide a means of obtaining very accurate control of the two properties investigated and of their possible combinations, and the same may well be true of other physical properties of fabrics.     

35—THE PREDICTION OF STRENGTHS OF LOCKSTITCH SEAMS IN WOVEN FABRICS

An absolute method of seam-strength testing is described. The effects of fabric type and gauge length on seam strength are examined. The effects of the type of sewing thread used and various measures of thread strength on the accuracy of seam-strength prediction are also investigated.

A simple method of determining the minimum loop strength of a thread is described. The efficiency of this value, corrected for one aspect of fabric construction, for seam-strength prediction is discussed.     

The Specific Heat of Hygroscopic Textiles

A comparison between the qualities of open-end- and ring-spun yarns produced from Egyptian cottons is reported. Yarns of different counts and twist factors were produced on both the BD 200 open-end-spinning machine and a conventional ring-spinning machine, and their quality was studied by determining their strength, uniformity, and number of imperfections. The quality of open-end-spun yarn relative to that of ring-spun yarn is expressed in terms of the relative quality factor.

It is shown that the percentage reduction in strength of open-end-spun yarns compared with that of ring-spun yarns can be minimized by spinning them to coarser counts from shorter cottons. This is attributed to the different interactions between the fibre properties and the mechanism of yarn formation when different types of cotton are used.

It is also shown that the relative quality of open-end-spun yarns can be considerably increased by spinning them to coarser counts from Ashmouni cotton. The quality of open-end-spun yarn can exceed that of ring-spun yarn when Ashmouni cotton is spun to a linear density exceeding 30 tex.

It is concluded that the BD 200 open-end-spinning machine cannot be recommended for spinning fine yarns from long-staple Egyptian cottons.     

25—USE OF A YARN HAIRINESS METER AND RESULTS SHOWING THE EFFECT OF SOME SPINNING CONDITIONS ON YARN HAIRINESS

An instrument developed for the measurement of yarn hairiness—the Yarn Hairiness Meter—has been in use by the Spinning Technology Department of the Shirley Institute for the past three years, and this paper gives the procedure to be adopted in using the instrument and results showing the effect of some spinning conditions on the hairiness of yarns spun from cotton and man-made fibres.     

16—THE PREPARATION,FINE STRUCTURE,AND PHYSICAL PROPERTIES OF PARTLY METHYLATED COTTON FABRICS

Cotton fabric has been methylated under a variety of conditions. The extent of methylation has been shown to be dependent on the time of methylation and on the degree of swelling or disruption of structure. The latter is caused by the alkali pretreatment or by the swelling of the partly methylated cellulose. Fabric physical properties have been measured and the influence of the methylation treatment has been examined.     

22—A THEORETICAL AND EXPERIMENTAL INVESTIGATION OF THE CREASE RECOVERY OF PLAIN-WEAVE FABRICS WOVEN FROM STAPLE YARNS

The retained angle at a crease is considered to be made up of two components: inelastic and frictional. A theoretical scheme has been developed that enables the inelastic component to be calculated from the appropriate fibre, yarn and fabric data and the calculations are illustrated for three fabrics.

An experimental investigation of the crease-recovery behaviour of these fabrics, in conjunction with the calculations described above, has established a method of deducing the frictional component from the low-curvature bending-recovery behaviour of a fabric, and it is thus possible to make an estimate of the fabric crease-recovery angle. The calculation has been carried out for a range of fabrics woven from eighteen fibre types, each in four different cover factors, and the results are shown to agree reasonably well with the measured crease-recovery angles for the same fabrics. The experimental results are discussed and some interesting relationships are pointed out; in particular it is shown that fabrics must be well relaxed if the full potential of a high-recovery fibre is to be realized.     

37—THE WRINKLING AND BENDING OF FUSIBLE INTERLININGS

A series of apparel fabrics were bonded both to a cotton base cloth and to a worsted base cloth. The fabrics were then wrinkled by the AKU tester under wet and standard atmospheric conditions, and their wrinkle severity was determined by means of the Sivim Wrinklemeter. Buckling and cantilever tests were also made, and the wrinkling behaviour and bending performance were compared.     

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.     

Improved Methods of Determining Fibre Density

An account is given of an investigation of the effects of fibre type (rayon, acrylic fibre, wool, and cotton) and dimensions on the properties of needled fabrics, the test methods used being those described in a previous paper. Some fabrics show a stick-slip behaviour in extension; others deform smoothly. Rayon webs consolidate more easily on needling than Courtelle or wool webs. Longer fibres give higher fabric strengths. Finer fibres also give higher strength, unless fibre damage occurs. The influence of fibre friction is discussed.     

25—THE DETERMINATION OF PENTACHLOROPHENYL LAURATE IN TEXTILE AND PAPER MATERIALS

Methods for the quantitative determination of pentachlorophenyl laurate (L.P.C.P.) in textile materials, described in British Standard 2087 and elsewhere, are reviewed, and it is demonstrated that a closer control of the quantities of added reagents is necessary. A modification in this respect to the existing British Standard method is proposed.

A further modification is proposed whereby the existing 2-hr boiling with 4N aqueous sodium hydroxide is replaced by boiling for 30 min with an ethylene glycol solution of sodium hydroxide. This modification gives good recovery of L.P.C.P. for materials containing components such as wax or elastomers, for which low recovery had previously been obtained, and, in addition, considerably shortens the time of the determination.     

16—THE VARIANCE BETWEEN ULTRA-SHORT LENGTHS OF YARN

A method for measuring the variance between ultra-short lengths of yarn is presented and shows that the reported flattening of the B(L) curve to a constant value in the B(0) region does not occur at lengths of down to at least 0.1 cm. The curve continues to rise logarithmically as the length decreases, possibly as far as 0.045 cm, though detection imperfections render readings at this length open to some doubt. Yarn irregularity is shown to be strongly dependent on fibre length and on yarn fineness, particularly at short test lengths, and the possibility of periodicities at less than 1-cm ‘wavelengths’ is shown to exist.