R. Innocenti

Identification of wool, cashmere, yak, and angora rabbit fibers and quantitative determination of wool and cashmere in blend: a near infrared spectroscopy study

Near infrared spectroscopy coupled with chemiometric analysis was investigated as a fast and non destructive method for the identification of wool, cashmere, yak, and angora rabbit fibers in the raw and combed sliver state and for the quantitative determination of cashmere in cashmere/wool blends. The main differences among spectra of different animal hair arise from physical charateristics rather than chemical characteristics (mainly pigmentation and mean diameter) of animal fibers. The Soft Independent Modelling by Class Analogy method allows the classification of distinct fibers into separate groups with interclass distances ranging from 12.64 for the nearest classes (white cashmere and wool) to above 1000 for the most distant classes of white and pigmented fibers. Percentages of recognition and rejection of 100 % were found with the exception of a yak sample that was not rejected from the pigmented cashmere class (98 % of rejection). The prediction capacity of the model was also evaluated. Quantitative analysis was carried out using samples obtained by carefully mixing known amounts of wool and white cashmere. A standard error of the estimate of 8.5, a standard error of prediction of 13.10 and a coefficient of determination of 0.95 were calculated. From the results obtained, it can be concluded that near infrared spectroscopy can be used as a tool for an initial and rapid screening of unknown animal fiber samples in the raw and combed sliver states and for a fast and coarse estimate of the amount of cashmere in wool/cashmere blends.

Enzyme‐aided wool dyeing with a neutral protease at reduced temperatures

Conventional wool dyeing methods are based on long times at high temperatures. These are energy intensive and can even damage the fibers, thus changing the desired fiber characteristics. In this work, enzyme pretreatment in combination with lower temperatures was used to reach exhaustion values comparable to those obtained with the standard procedure at 98°C. Kinetic runs carried out on wool yarn at different temperatures confirmed the possibility of obtaining more than 90% of bath exhaustion by dyeing at 85°C due to the pretreatment with a proteolytic enzyme. At the same temperature, without enzymatic pretreatment, just 77% of bath exhaustion can be reached. The enzyme action on the dyeing kinetics was investigated through calculation of dye absorption rate constants according to the diffusion‐limited kinetic model proposed by Chrastil. Dynamometric measurements on the yarn dyed at 98°C showed a 25% loss of tensile strength and 50% loss of elongation, while at lower temperature the values were better even after enzyme pretreatment, in agreement with the results of scanning electron microscopy analysis. A temperature of 85°C with enzyme pretreatment was found to be optimal taking into account satisfactory washing, perspiration and light fastness values.

Process Optimization and Industrial Scale-Up of Chitosan Based Anti-Felting Treatments of Wool

Abstract Anti-felting properties of knitted wool fabrics treated with chitosan were investigated, by both a laboratory scale treatment and a semi-industrial application. The influence of oxidative wool pre-treatments was analysed. The distribution of chitosan on treated wool fibres was also assessed using both qualitative and quantitative evaluation methods. The study provided shrinkage data perfectly comparable with those obtained by the currently used shrinkproofing processes, but with two important advantages: the total absence of chlorine in the process and the complete biodegradability of chitosan. The semi-industrial treatment showed the complete reproducibility of the laboratory scale results, giving rise to the possibility of an industrial adaptation of the process.

Characterization of Plasma-coated Wool Fabrics

(Si : Ox : Cy : Hz) thin films were deposited on knitted wool fabrics by plasma-enhanced chemical-vapor deposition using hexamethyldisiloxane as a monomer and argon and oxygen as feed gases in low-pressure equipment. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses confirmed the presence of the siloxane coating. The pilling tendency of treated samples was investigated for different deposition powers, ranging from 30 to 50 W. A reduction on pill formation was observed for all treated samples. A silicone-based wet chemical treatment was taken as the reference method for pilling reduction and plasma treatments were compared with it. The pilling grade of treated fabrics was also tested after washing and the results confirmed a good pilling behavior of plasma-treated fabrics. Changes were observed in the bursting resistance of plasma-treated wool samples compared with untreated ones, while no significant differences were found in the whiteness index.

Influence of protease on dyeing of wool with acid dyes

AbstractThe application of enzymes in the wool dyeing process is an important research goal in order to reduce the environmental impact and costs of this finishing process. The work has focused on the possibility of reducing the temperature of conventional dyeing, using an enzymatic pretreatment with a neutral protease to improve the diffusion of the dye into the fibers. After the identification of the optimal dyeing process, the study goes on transferring the method to an industrial application. For this reason the influence of a leveling agent added to the dyeing bath was considered and further tests with an industrial dyeing recipe were performed. In order to evaluate possible fiber damage, samples treated with enzyme were observed by scanning electron microscopy (SEM) and analyzed by gel electrophoresis (SDS-PAGE). Moreover, the variation of tensile strength and elongation of dyed samples were determined. In addition, color fastness to domestic laundering, perspiration and rubbing were carried out. Finally, color measurements and fiber section analysis were performed. The results show the possibility, thanks to the pretreatment with the investigated enzyme, to obtain a homogeneous and solid dyeing on fibers maintaining good mechanical properties, already working at 85°C instead of 98°C currently used in industry.

Mechanical Properties of Silk Yarn Degummed with Several Proteases

Abstract The silk filament spun by the silkworm (Bombyx mori) is composed of two fibroin filaments held together by a cementing layer of sericin. Fibroin and sericin account for about 75 wt% and 25 wt% of the raw silk, respectively. The degumming process consists in removing the sericin layer prior to dyeing using a solution of soap, synthetic detergents, or proteolytic enzymes. Silk yarn was degummed with different commercially available enzymes, two alkaline, a neutral, and an acidic proteases and the results were compared in terms of physical and mechanical properties. Proteases were used under optimum conditions of pH and temperature. The treatments were carried out with three different enzyme dosages, that is, 0.2, 1, and 5 U/g yarn. Soap was taken as the standard method of degumming and enzymatic treatments were compared with this method. The degree of polymerization of silk fibroin was assessed by measuring the intrinsic viscosity of the treated samples.

Cotton fabric functionalisation with menthol/PCL micro- and nano-capsules for comfort improvement.

Abstract Objective: Cotton functionalisation with poly-ɛ-caprolactone (PCL) micro- and nano-capsules containing menthol was carried out with the aim of introducing a long-lasting refreshing sensation. Materials and methods: The preparation of the polymer micro- and nano-capsules was carried out by solvent displacement technique. A confined impinging jets mixer was used in order to ensure fast mixing and generate a homogeneous environment where PCL and menthol can self-assemble. Results: The micro- and nano-capsules and the functionalised fabrics were characterised by means of DSC, FT-IR spectroscopy and SEM imaging. Micro- and nano-capsules of different size, from about 200 to about 1200 nm, were obtained varying menthol to PCL ratio (from 0.76 to 8), overall concentration and flow rate (i.e. mixing conditions). The inclusion of menthol was confirmed by DSC analysis. Discussion and conclusion: A patch test was carried out by 10 volunteers. Micro-capsules were found to be effective in conferring the fabric a refreshing sensation without altering skin physiology.

Enzyme-aided wool dyeing: Influence of internal lipids

Dyeing and diffusion properties of dyes into wool fiber are governed by a membranous structure which is formed by a matrix protein and lipid components. External lipids (wool wax) are mainly non-polar, while internal lipids consist mainly of sterols, polar lipids (ceramides), and free fatty acids. These components constitute a real hydrophobic barrier to the diffusion of dye molecules and in fact conventional wool dyeing methods are based on long times at temperature near the boil in order to ensure good levels of dye penetration. To limit the action of this barrier and to achieve higher values of dye bath exhaustion operating at temperatures lower than 98 °C, wool fabric was subjected to three different pre-treatments. The first pre-treatment consisted of the removal of internal lipids by extraction with solvents in order to obtain a higher affinity of the fiber towards the dyes. The second involved hydrolysis with a protease, which leads to the formation of access routes within the fiber to improve the uptake of dyes or other reagents. Finally, the third took into account the combined action of the two previous pre-treatments. The influence of each individual pre-treatment and their combinations on the kinetics and final exhaustion of the dye bath were studied, and assessment of color fastness (to washing and to light) were carried out.

Eumelanin in Human Hair. A new approach in the determinatiion of eumelanin in human hair using near infrared spectroscopy

Page 10 NIR news Vol. 16 No. 6 (2005) The aetiology of skin cancers is a complex interaction between genetic characteristics (phenotypically expressed by skin complexion) and exposure to sun. These two factors, complexion and exposure to sun, modulate the risk of different tumours in a different way. In detail, for melanoma, risk is associated with fair complexion (light blonde or red hair, high number of naevi and freckles, tendency to sunburn) and with intense and intermittent exposures like those experienced during holidays. Risk profiles are defined by semi-quantitative empiric parameters (scale of hair, eye and skin colour, acute reactivity scale, such as MED, Minimal Erithemal Dose) for the tendency to sunburn. Knowledge of the biochemistry of skin pigments, the melanins, has made it possible to identify a biological marker. Melanins are biopolymers present in the hair and epidermis. There are two distinct types of melanin pigments: the eumelanins, efficient in photo-protection and responsible for black and brown colour and the pheomelanins, bad at photo-protection and responsible for yellow and reddish colour. Most Caucasian populations have intermediate skin and hair colour and present these two kind of pigment in different ratios. This study about the distribution of melanin pigment in the population in general and in groups of subjects with different cutaneous tumours is an original work, starting from results obtained in the biochemical field. The turning point from empirical characterisation to biochemical characterisation of phenotypes by the quantitative determination of melanins in human hair can lead to the selection of groups with an elevated risk of cutaneous tumours. In these groups of people it will be possible to carry out more thorough diagnostic tests (dermatological inspection of skin). A multicentric case-control study was carried out in different European countries. Three groups of about 300 cases were recruited for each cutaneous cancer (cutaneous melanoma, squamous cell carcinoma and basal cell carcinoma) and 300 controls. For each group of people, in addition to data concerning phenotype and sun exposure Eumelanin in Human Hair