Effects of ultrasonic treatment on wool fibre and fabric properties

The protein structures of wool, treated in fabric form with ultrasonics for different time durations, were analysed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR), in comparison with the wool without ultrasonic treatment. Fabric water absorption and tensile properties were measured in addition to the fibre micro-structure analysis. It is shown that while the ultrasonic treatment had little effect on the fibre crystallinity, some chemical structures in the protein were altered to some extent during the process. Disruption of fibre internal waxy lipids upon ultrasonic treatment provided the fibres with increased water absorption. Protein chains in the macro fibrils were shown to be rearranged to a more regular and less flexible structure, as a result of the ultrasonic treatment. Fabric tensile tests showed an increased tenacity and a reduced extensibility to the ultrasonically treated fabric. Prolonged ultrasonic treatment, however, significantly reduced both fabric tenacity and extensibility.

Production, properties and processing of American bison (Bison bison) wool grown in southern Australia

American bison grow a thick coat of fibres which assists them to withstand severe climatic conditions. Bison fibre was traditionally used in textiles by native North Americans. This study aimed to quantify the production, fibre attributes and dehairing processing of bison fibre produced from bison grazed in north-eastern Victoria. Three age/sex classes were sampled (n = 16) at seven body positions in spring. The fibre growing area was measured. Fibre was tested for diameter distribution, clean washing yield, proportion of fine fibres <36µm and fine fibre length, and processed by cashmere dehairing. Bison were 12 years of age, liveweights 160450 kg and had mean fibre growing area of 1.4 m². They produced an average 1184 g (range 5301640 g) of fine fibre with mean fibre diameter 18.5µm, clean washing yield 76.5%, wax content 9.8%, suint content 14.5%, clean fine fibre yield 56.4%, fine fibre length 37 mm and fibre curvature was 93/mm. Mid-side fibre had a crimp frequency of 6.5/cm and mean resistance to compression of 6.6 kPa. Fibre had a tenacity of 8.7 cN/tex and an extension of 39.3%. Restricted maximum likelihood mixed model analysis showed age/sex class and sampling site significantly affected all fibre attributes. Finer and longer fibre was produced in anterior sites and in younger bison. Fibre curvature declined 5.3°/mm for each 1-µm increase in mean fibre diameter. Dehaired fibre had a mean fibre diameter of 17.8 µm and mid-length of 28 mm, suitable for woollen spinning. The production by bison of coats containing significant amounts of fibre indicates that careful harvesting of fibre could form an important source of income in bison enterprises.

Changes in wool protein structure and fabric properties with ultrasonic treatment

Wool fabrics, ultrasonically treated for different time durations, were analysed by Fourier transform infrared (FTIR), differential scanning calorimeter (DSC), and thermo-gravimetric analysis (TGA), in comparison with the wool without ultrasonic treatment. Fabric tensile and thermal properties were measured in addition to the fibre micro structure analysis. Wool protein chains in the macro fibrils were shown to be rearranged to a more regular and less flexible structure, as a result of the ultrasonically treated fabric. Prolonged ultrasonic treatment, however, significantly reduced both fabric tenacity and extensibility. Wool treated with ultrasonics was found to have less mass loss and a higher thermal degradation temperature than that of without ultrasonic treatment and prolonged treated. DSC analysis showed that while ultrasonic treatment has little effect on the fibre crystallinity, an appropriate treatment can provide wool with increased water absorption.

Effect of fibre, yarn and knitted fabric attributes associated with wool comfort properties

In this replicated experiment, we investigated the comfort properties of single jersey fabrics composed of cashmere in blends with superfine wools of different fibre curvature (crimp) where the fibre diameter of the wool and cashmere were tightly controlled. The 81 fabrics were evaluated using the Wool ComfortMeter (WCM) which has been calibrated using wearer trials of wool knitwear. General linear modelling determined the best prediction models for log10 transformed fabric WCM values using 27 fibre, 16 yarn and 30 fabric attributes. Tighter fabrics were less comfortable. Progressively blending cashmere with wool progressively increased comfort assessment. The WCM was able to detect differences between fabrics which were more supple and springy, thinner and lighter, and were composed of more elastic, uniform and stronger yarns. Together these attributes explained 82% of the variance in WCM value.

Relationship between wearer prickle response with fibre and garment properties and Wool ComfortMeter assessment

The prickle evoked by 48 knitted fabrics was assessed by wearers under a defined evaluation protocol. The relationship between the average wearer prickle score and known properties of constituent fibre, yarns and fabrics and fabric evaluation using the Wool ComfortMeter (WCM) was determined using linear modelling. After log transformation, the best model accounted for 87.7% of the variance. The major share of variation could be attributed to differences between mean fibre diameter (MFD) and WCM values. Low prickle scores were linearly associated with lower MFD, lower WCM and lower yarn linear density. There was an indication that yarn twist affected prickle scores and that fabrics composed of cotton evoked less prickle. Measures of fibre diameter distribution or coarse fibre incidence and other fabric properties were not significant. The analysis indicates that wool garments can be constructed to keep wearer assessed prickle to barely detectable levels and textile designers can manipulate a range of parameters to achieve similar wearer comfort responses.

Effect of surface treatment and knit structure on comfort properties of wool fabrics

The comfort properties of the pique and single jersey knitted wool fabrics were investigated using the Wool ComfortMeter (WCM). The fabrics were knitted in three cover factors and treated with either plasma or a silicone softening agent and were compared with untreated fabrics. Plasma treatment did not show significant effects on the comfort value. However, silicone polymer significantly reduced WCM values suggesting that the silicone coating reduced the number of protruding fibres on the fabric surface. Regardless of treatment used, pique fabrics showed a lower WCM value, and therefore were perceived to be more comfortable than the single jersey structure. While the effect of cover factor was not significant, in fitted model to predict the WCM value of fabrics, mass/unit area and fabric thickness were significant predictors along with fabric structure and finishing treatment.

Predicting comfort properties of knitted fabrics by assessing yarns with the Wool ComfortMeter

This study examined the feasibility of assessing yarns with the Wool ComfortMeter (WCM) to predict the comfort properties of the corresponding single jersey-knitted fabrics. The optimum yarn arrangement to predict the comfort value of a corresponding control fabric was determined using nine wool and wool/nylon-blended yarns (mean fibre diameter range 16.5–24.9 μm) knitted into 34 different fabrics. Using a notched template, yarn winding frequencies of 1, 3, 6, 12, 25 and 50 parallel yarns were tested on the WCM. The best predictor of fabric WCM values was using 25 parallel yarns. Inclusion of knitting gauge and cover factor slightly improved predictions. This indicates that evaluation at the yarn stage would be a reliable predictor of knitted fabric comfort, and thus yarn testing would avoid the time and expense of fabric construction.

The Wool ComfortMeter and the Wool HandleMeter, new opportunities for wool

Two instruments have been developed by the Sheep CRC that provide the tools for a new standard in comfort and handle for the next generation of next-to-skin wool knitwear. The Wool ComfortMeter and Wool HandleMeter provide a rapid, accurate and objective measure of two important characteristics of wool knitwear that are currently determined by subjective assessment. The Wool HandleMeter allows the prediction of a set of handle attribute values that can quantify the hand feel of a lightweight jersey fabric. The instrument uses the principle of pushing a fabric sample through a ring. The force displacement curve associated with the fabric test is characterised and used to define each fabric. These values were then compared to the average handle values, as determined by a group of experts, of a large set of lightweight knitted fabrics. Algorithms were developed that enable the instrument to more accurately predict each of seven handle attributes than an individual expert. The Wool ComfortMeter provides a measure of the fibres that are protruding from the surface of the fabric that are responsible for the itchy sensation caused by some knitwear. The results from the instrument have been compared to the results from extensive wearer trials to provide an understanding of the relationship between the instrument value and the comfort perceptions of wearers. The results have shown a very clear relationship between the instrument and wearer trials.