The art of wool

A curatorial project that brings together garments from the International Woolmark Prize archive with works from the Howard Hinton and Chandler Coventry Collections at New England Regional Art Museum. Themed around qualities of wool that are also present in the artworks, the exhibition considers attributes such as Production, Romance, Pattern, Texture, Drape and Artistry. From the sale yards and shearing sheds of the New England landscape to the international catwalks, merino wool provides a staple thread made durable through works from these extraordinary collections.

Microstructure and hardness characterisation of laser coatings produced with a mixture of AISI 420 stainless steel and Fe-C-Cr-Nb-B-Mo steel alloy powders

Fe-C-Cr-Nb-B-Mo alloy powder and AISI 420 SS powder are deposited using laser cladding to increase the hardness for wear resistant applications. Mixtures from 0 to 100 wt.% were evaluated to understand the effect on the elemental composition, microstructure, phases, and microhardness. The mixture of carbon, boron and niobium in the Fe-C-Cr-Nb-B-Mo alloy powder introduces complex carbides into a Fe-based matrix of AISI 420 SS which increases its hardness. Hardness increased linearly with increasing Fe-C-Cr-Nb-B-Mo alloy, but substantial micro-cracking was observed in the clad layer at additions of 60 wt.% and above; related to a transition from a hypoeutectic alloy containing α-Fe/α' dendrites with an (Fe,Cr)2B and γ-Fe eutectic to primary and continuous carbo-borides M2B (where M represents Fe and Cr) and M23(B,C)6 carbides (where M represents Fe, Cr, Mo) with MC particles (where M represents Nb and Mo). The highest average hardness, for an alloy without micro-cracking, of 952 HV was observed in a 40 wt.% alloy. High stress abrasive scratch testing was conducted on all alloys at various loads (500, 1500, 2500 N). Alloy content was found to have a strong effect on the wear mode and the abrasive wear rate, and the presence of micro-cracks was detrimental to abrasive wear resistance.

Production of Ti-6Al-4V billet through compaction of blended elemental powders by equal-channel angular pressing

In this work, compaction by warm equal-channel angular pressing (ECAP) with back pressure was used to produce Ti-6Al-4V billets from both commercially pure (CP) titanium and titanium hydride (TiH 2) powders, which were mixed with pulverised binary Al-V master alloys of two distinct Al/V ratios and with elemental aluminium powder to arrive at the nominal alloy composition. It was demonstrated that the right combination of temperature, high hydrostatic pressure and plastic shear deformation permits consolidation of the powder mixture to maximum green densities of 99.26%. Moreover, after direct compaction of blended elemental powders by equal-channel angular pressing (ECAP) with back pressure, the sintering temperature required for chemical and microstructural homogenisation of the compacts could be reduced by 150-250°C. This was possible due to high green density, increased contact area between powder particles and the formation of fast diffusion paths associated with grain refinement by severe plastic deformation. The sintered Ti-6Al-4V billets exhibited a maximum density of 99.88%, Vickers hardness of 409-445 HV1 and ultimate tensile strength in the range of 1000-1080MPa. In contrast to findings of other authors, the use of TiH 2 powders in conjunction with ECAP processing did not bring any benefits with regard to the production of the Ti-6Al-4V alloy.

Predicting fabric prickle propensity by testing yarns on the Wool ComfortMeter

The Wool ComfortMeter is the first simple and fast objective tool in the world for assessing wool fabric prickle propensity. IWTO-DTM-66 for the measurement of fabrics using the WCM was accepted at the IWTO Cape Town Congress, South Africa in 2014. Since then, interest has been shown in the technology by yarn manufacturers and buyers for testing yarns before fabric is made, in order to obtain the prickle propensity of a fabric while still at yarn stage.Presentation of the yarn sample to the Wool ComfortMeter is critical. An YG381 yarn winder was selected for this project because it is a fast and reliable tool for sample preparation. The investigation into yarn winding density and tension showed that both the winding density and tension did not significantly affect the tested yarn WCM values. Therefore, a sample preparation protocol was established by using a winding density 19 loops/cm and a 20g tension plate on the YG381 winding machine.Further examination by complying with the preparation protocol showed that yarn Wool ComfortMeter value was the only significant predictor of its corresponding fabric Wool ComfortMeter value. Thus, liner and polynomial regression models were developed for predicting the fabric WCM prickle propensity. Based on the prediction performance, a linear model was recommended for the 1-ply yarns and polynomial model for the 2-ply yarns in this report. The prediction errors were approximately 66 for the 1-ply yarns and 14 for the 2-ply yarns.

Report on the second Wool ComfortMeter round trial

The present report analysed the variance between instruments and estimated the measurement precision of the Wool ComfortMeter instrument by conducting an international round trial. The firstinternational round trial was conducted in 2014; however the calculated precision estimates were relatively large. In the present trial, instruments were standardised by harmonising parameters such as wire height and measuring length, and a new calibration method was used to improve the measurement precision. The data from five laboratories, measuring ten fabric-samples and 5 sub-samples per fabric sample, was used to estimate the components of variance and the prickle measurement precision. The results showed good agreement between laboratory measurements. Analysis of the data shows an improvement in the 95% confidence limit for this round trial compared to the first round trial. Particularly, relatively smaller confidence limits were found for low prickle measurements. It is recommended that the new precision estimates be incorporated into the IWTO DTM-66:2014.

Comparison of different extrusion methods for compaction of powders

Densification of metallic powders by means of extrusion is regarded as a very attractive processing technique that allows obtaining a high level of relative density of the compact. However, the uniformity of the relative density depends on that of strain distribution and on the processing parameters. Several variants of extrusion can be used for compaction of metal particulates, including the conventional extrusion (CE) and equal channel angular pressing (ECAP), often referred to as equal-channel angular extrusion. Each of these processes has certain advantages and drawbacks with respect to compaction. A comparative study of these two extrusion processes influencing the relative density of compacts has been conducted by numerical simulation using commercial finite element software DEFORM2D. The results have been validated by experiments with titanium and magnesium powders and chips.

Coarser wool is not a necessary consequence of sheep aging: allometric relationship between fibre diameter and fleece-free liveweight of Saxon Merino sheep

The mean fibre diameter (MFD) of wool is the primary determinant of price, processing performance and textile quality. This study determines the primary influences on MFD as Saxon Merino sheep age, by allometrically relating MFD to fleece-free liveweight (FFLwt). In total, 79 sheep were grazed in combinations of three stocking rates and two grazing systems (GS: sheep only; mixed with Angora goats) and studied over 3 years. Measurements were made over 14 consecutive periods (Segments), including segments of FFLwt gain or FFLwt loss. Using shearing and liveweight records and dye-bands on wool, the FFLwt and average daily gain (ADG) of each sheep were determined for each segment. The mean and range in key measurements were as follows: FFLwt, 40.1 (23.1 to 64.1) kg; MFD, 18.8 (12.7 to 25.8) μm. A random coefficient restricted maximum likelihood (REML) regression mixed model was developed to relate the logarithm of MFD to the logarithm of FFLwt and other effects. The model can be written in the form of ${\rm MFD}\,{\equals}\,\rkappa \left( {{\rm GS,}\,{\rm A}{\rm ,}\,{\rm Segment}{\rm .Plot,}\,{\rm Segment,}\,{\rm ADG}} \right){\times}{\rm FFLwt}^{{\left( {\ralpha \left( {{\rm GS}} \right){\plus}\rbeta \left(\rm A \right){\plus}\rgamma \left( {{\rm Segment}{\rm .Plot}} \right)} \right)}} $ , where $\ralpha \left( {{\rm GS}} \right)\,{\equals}\,\;\left\{ {\matrix{\!\! {0.32\left( {{\rm SE}\,{\equals}\,{\rm 0}{\rm .038}} \right)\,{\rm when}\,{\rm sheep}\,{\rm are}\,{\rm grazed}\,{\rm alone}} \hfill \cr \!\!\!\!{0.49\left( {{\rm SE}\,{\equals}\,{\rm 0}{\rm .049}} \right)\,{\rm when}\,{\rm sheep}\,{\rm are}\,{\rm mixed}\,{\rm with}\,{\rm goats}} \hfill \cr } } \right.$ β(A) is a random animal effect, γ(Segment.Plot) a random effect associated with Segment.plot combinations, and κ a constant that depends on GS, random animal effects, random Segment.plot combination effects, Segment and ADG. Thus, MFD was allometrically related to the cube root of FFLwt over seasons and years for sheep, but to the square root of FFLwt for sheep grazed with goats. The result for sheep grazed alone accords with a primary response being that the allocation of nutrients towards the cross-sectional growth of wool follicles is proportional to the changes in the skin surface area arising from changes in the size of the sheep. The proportionality constant varied systematically with ADG, and in sheep only grazing, was about 5 when sheep lost 100 g/day and about 6 when sheep gained 100 g/day. The proportionality constant did not systematically change with chronological age. The variation in the allometric coefficient between individual sheep indicates that some sheep were more sensitive to changes in FFLwt than other sheep. Key practical implications include the following: (a) the reporting of systematic increases in MFD with age is likely to be a consequence of allowing sheep to increase in size during shearing intervals as they age; (b) comparisons of MFD between sheep are more likely to have a biological basis when standardised to a common FFLwt and not just to a common age;

Fabric and greasy wool handle, their importance to the Australian wool industry: a review

Handle-related properties of woollen fabrics have been demonstrated to be major factors affecting consumer buying attitudes. Handle is the combination of both textural and compressional attributes. Compressional handle has demonstrated processing advantages in woven and knitted fabrics. The handle of processing lots can be manipulated using a variety of technologies but direct manipulation of textural greasy wool handle pre-processing is still crude. On-farm, there is documented evidence that including handle assessment in a selection index provides additional improvements in genetic gain. However, the assessment of greasy wool handle is based on a tactile evaluation of the wool staple by sheep and wool classers, and its application is affected by a lack of framework that instructs assessors on a standard method of assessment. Once a reliable and repeatable protocol is developed, further understanding of the effect greasy wool handle has on final garment quality will be possible.

Functionality of nano titanium dioxide on textiles with future aspects: focus on wool

The consumption of titanium dioxide in today's world is on the increase. As the most popular nano substance, TiO 2 is used in various industries notably in the textile industry. More and more recently, through a synergistic combination of photocatalytic features of nanoparticles, fabrics with novel properties are produced. Self-cleaning and stability against UV rays as well as chemical media, to name but a few, are among new prominent properties, obtained on textiles. A common subject reported in most studies has been the diverse approaches to immobilize the nanoparticles on the surface of fabrics. Wool is among common textile materials that have undergone numerous processes to be modified. This review intends to bring to light different aspects of application of nano titanium dioxide in the textile industry especially on wool, and also presents a concise overview on the rigorous pieces of research conducted in this realm.

Electrical conductivity of single walled and multiwalled carbon nanotube containing wool fibers

The main purpose of this study was producing conductive wool fabric applying carbon nanotubes. Raw and oxidized wool samples were treated with carbon nanotubes in the impregnating bath in the presence of citric acid as a crosslinking agent and sodium hypophosphite as a catalyst while sonicating them in the ultrasonic bath. Electrical resistance, washing durability, and color variation of treated samples were assessed. Through SEM images, the surface morphology of treated samples was studied confirming the surface coating through carbon nanotubes. According to the results, the electrical resistance of treated wool with carbon nanotubes reduced substantially. However, the single-walled carbon nanotubes are more useful to increase the conductivity. In addition, the wool color changed into gray after the treatment.

Novel feature of nano-titanium dioxide on textiles: antifelting and antibacterial wool

In this study, the antifelting and antibacterial features of wool samples treated with nanoparticles of titanium dioxide (TiO2) were evaluated. To examine the antifelting properties of the treated samples, the fabric shrinkage after washing was determined. The antimicrobial activity was assessed through the calculation of bacterial reduction against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. TiO 2 was stabilized on the wool fabric surface by means of carboxylic acids, including citric acid (CA) and butane tetracarboxylic acid (BTCA). Both oxidized samples with potassium permanganate and nonoxidized wool fabrics were used in this study. The relations between both the TiO2 and carboxylic acid concentrations in the impregnated bath and the antifelting and antibacterial properties are discussed. With increasing concentration in the impregnated bath, the amount of TiO2 nanoparticles on the surface of the wool increased; subsequently, lower shrinkage and higher antibacterial properties were obtained. The existence of TiO2 nanoparticles on the surface of the treated samples was proven with scanning electron microscopy images and energy-dispersive spectrometry.

Photo induced silver on nano titanium dioxide as an enhanced antimicrobial agent for wool

In this study an effective nanocomposite antimicrobial agent for wool fabric was introduced. The silver loaded nano TiO(2) as a nanocomposite was prepared through UV irradiation in an ultrasonic bath. The nanocomposite was stabilized on the wool fabric surface by using citric acid as a friendly cross-linking agent. The treated wool fabrics indicated an antimicrobial activity against both Staphylococcus aureus and Escherichia coli bacteria. Increasing the concentration of Ag/TiO(2) nanocomposite led to an improvement in antibacterial activities of the treated fabrics. Also increasing the amount of citric acid improved the adsorption of Ag/TiO(2) on the wool fabric surface leading to enhance antibacterial activity. The EDS spectrum, SEM images, and XRD patterns was studied to confirm the presence of existence of nanocomposite on the fabric surface. The role of both cross-linking agent and nanocomposite concentrations on the results was investigated using response surface methodology (RSM).

Self-cleaning and color reduction in wool fabric by nano titanium dioxide

Wool is a textile material that is valued for its strength, warmth, water resistance, and texture. But this natural fiber of the protein keratin lacks the stain resistance of synthetic fabrics and is also generally susceptible to harsh processing conditions. In this study, raw and oxidized wool fabrics were treated with nano titanium dioxide (TiO2) powder in an ultrasonic bath. These particles were linked to the wool surface by butane tetra carboxylic acid and also sodium hypophosphite was used as a catalyst. The photo-catalytic activity of TiO2 nanoparticles deposited on the wool fabrics was followed by the degradation of Acid Blue 113 as a stain and also determined by the degradation rate of food stains such as coffee, tea, and fruit juice under the ultraviolet rays. The results showed that increasing the amount of nano TiO2 leads to improved degradation of stains on the treated fabric.

Nano titanium dioxide on wool keratin as UV absorber stabilized by butane tetra carboxylic acid (BTCA): a statistical prospect

Photo yellowing of wool is one of the most important problems which have negative impacts on various aspects of wool prompting scientists to find a solution over the past decades. In this research the protective features of nano-titanium dioxide particles against UV on wool fabric were discussed and the color variations of wool samples after UV irradiation were measured and reported. It was shown that nano TiO2 is a suitable UV absorber and its effect depends on the concentration. Also, it was assumed that butane tetracarboxylic acid plays a prominent role as a cross-linking agent to stabilize the nano-titanium dioxide as well as a polyanion to maintain negative charges on the wool surface for higher nano particles absorption. Also the variables conditions were optimized using response surface methodology (RSM).