Giorgio Mazzuchetti

Electrospun Porous Mats for High Efficiency Filtration

Submicron size fibers (so-called nanofibers) are easily produced with an electrospinning apparatus from polymer solutions of poly(ethylene oxide), poly(vinyl alcohol), and polyamide-6. Electrospinning seems the most powerful tool for fabricating polymer nanofibers. Fibers were directly deposited in the form of random fiber webs with high area-to-volume ratio and small porous size on ordinary nonwoven filters of PET microfibers. Morphology and diameter distribution of the electrospun filaments were characterized by SEM investigations. The flow resistance of the produced composite filters are evaluated by means of air permeability measurements. The electrospun fibers have diameters ranging from about 70—500 nm and are interconnected each other to form thin webs that have very small pore size. After the electrospinning treatment, the air permeability of the filter media decreases 6—17 times showing a significant change of flow resistance that can be controlled by the thickness of nanofibers layer and the pore size. High efficiency nano-microfibers composite filters could be used in a wide range of applications, ranging from air cleaning for automotive to environment conditioning or liquid filtration.

Antibacterial efficacy of polypyrrole in textile applications

This paper describes application and evaluation of polypyrrole as an antibacterial polymer. Polypyrrole was produced embedding two doping agents: chloride and dicyclohexyl sulfosuccinate ions. Stability of the antibacterial efficacy of polypyrrole deposited on cotton fabrics was assessed before and after three different kinds of washing (namely, laundering with anionic and non-ionic detergents and dry-cleaning). Polypyrrole showed excellent antibacterial properties (100 % of bacterial reduction) against Escherichia coli for both doping agents. Treated fabrics were further characterised by scanning electron microscopy, energy dispersive X-ray analysis and infrared spectroscopy. The antibacterial efficacy diminished after launderings with anionic and non-ionic detergents because of two different mechanisms: the neutralisation of positive charges under alkali conditions (dedoping), and a partial removal of polypyrrole by abrasion and surfactant action. After dry-cleaning, polypyrrole embedding chloride and dicyclohexyl sulfosuccinate ions still showed excellent antibacterial efficacy. Moreover, scanning electron microscopy investigations were used to intuitively explain the bactericidal mechanism of polypyrrole on Escherichia coli bacteria.

Wool-derived keratin nanofiber membranes for dynamic adsorption of heavy-metal ions from aqueous solutions

Membranes made of randomly oriented wool-derived keratin nanofibers (∼240 nm mean diameter), were prepared by electrospinning process, and tested for the Cu(II), Ni(II), and Co(II) metal ion removal from aqueous solutions, through dynamic adsorption tests. The Cu(II) ion adsorption was studied from the isotherm and kinetic point of view, both in non-competitive and competitive conditions. As regards the non-competitive condition, the experimental data had a very good fit with both Langmuir and Freundlich isotherm models. The maximum adsorption capacity obtained from the Langmuir model was about 11 mg/g and the high correlation coefficient of the BET model indicates that the adsorption was a multilayer process. The mean free energy of adsorption, evaluated through the Dubinin–Radushkevich model, was 14.1 kJ/mol, indicating that the adsorption of Cu(II) ions on keratin nanofiber membranes occurred by ion exchange reactions. The process kinetics was evaluated by pseudo-first and pseudo-second order models, the latter showing the highest correlation with the experimental data. The competitive adsorption tests evidenced that the keratin nanofiber membranes maintained a good adsorption capacity for Cu(II) ions and also with the coexistence of Co(II) and Ni(II) metal cations. As regards the selectivity studies, the results showed that the adsorption of metal ions by keratin nanofiber membranes followed the order Cu(II) > Ni(II) > Co(II).

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 Nonwoven Fabrics' Physical Parameters on Thermal and Water Vapor Resistance

This article takes into consideration some constructive parameters of needled nonwoven fabrics used as padding in winter clothes, and their influence on thermal resistance Rct and water vapor resistance Ret. The nonwoven fabric features taken into consideration were the following: substance fibers, their average linear density, and their bulk density. Nonwoven fabrics examined had a fiber content varying from 0.5% to 4% of the total volume of the sample. In these particular conditions, the results obtained showed that the fiber substance has little influence on Rct and Ret. Instead, the average fiber linear density and bulk density of nonwoven fabrics are very important for an accurate design in order to optimize comfort performance.

KES-F Characterization and Hand Evaluation of Oxygen Plasma-Treated Wool Fabrics Dyed at Temperature Below the Boil

In our previous works, we investigated the possibility of reducing the dyeing temperature of wool fabrics with oxygen low-temperature plasma pre-treatment. Fabrics were dyed replicating an industrial process on a laboratory-scale machine, and it was found that pre-treated fabrics could be dyed at 85°C with no worsening of their dyeing performances compared with fabrics conventionally dyed at the boil. In this work, the physical, low-stress mechanical and surface properties of untreated fabrics, untreated fabrics conventionally dyed at 98°C, and plasma-treated fabrics dyed at 85°C, were measured using Kawabata’s Evaluation System for Fabrics. In particular, there were significant increases in bending and shearing characteristic values for plasma-treated fabrics dyed below the boil (85°C). Moreover, subjective hand tests highlighted that these fabrics were stiffer and crisper than the other two types of fabric, thus confirming the results of objective measurements.

Differential scanning calorimetry for the identification of animal hair fibres

Differential scanning calorimetry (DSC) was studied as an alternative qualitative method to identify different textile animal hair fibres. Differentiation of speciality or luxury fibres (such as cashmere) from other animal cheaper fibres (such as sheep’s wool or yak) is essential to repress adulteration of textile products. Moreover, DSC analysis can be used to distinguish fibres of different types and affected by industrial textile treatments like bleaching, steaming, descaling and stretching. Cashmere, wool, yak and goat fibres were analysed by DSC and their traces were compared. The traces were mathematically elaborated to establish criteria for fibres identification. These criteria were applied to study changes in the fibre traces due to industrial treatment. Differences in the DSC traces are evident from cashmere, yak, wool and goat due to differences in transition enthalpy and temperature of the crystalline material that constitutes the ortho- and para-cortex of animal hairs. Furthermore, it is possible to see changes in traces of the same fibres subjected to different treatments.

Effect of Carbon Dioxide Dry Cleaning on Low-stress Mechanical Properties, Air Permeability and Crease Pressing Performance of Men’s Suit Fabrics

Carbon dioxide (CO2) is becoming a promising alternative to perchloroethylene in dry cleaning. In this work, the effect of CO2 dry cleaning on some physical and mechanical properties of six different pure wool and wool/cashmere fabrics was investigated in order to detect any possible fabric modification. It was found that the CO2 dry cleaning process especially affected the thickness and compressional energy, making the fabrics thicker and fuller. A marked increase in shear hysteresis was detected, while no particular variations in bending and tensile properties or crease pressing performance were noted. Finally, there was a significant decrease in the air permeability of three of the six fabrics involved.

Reversible and washing resistant textile-based optical pH sensors by dyeing fabrics with curcuma

Curcuma powder was used to dye cotton and polyamide 6,6 fabrics in order to produce textile-based optical pH sensors. Both fabrics showed a bright yellow color after dyeing and demonstrated color changes (towards red) when contacted with basic solutions. Color change and sensitivity differ for cotton and for polyamide. Curcuma-dyed cotton shows color changes in particular in the range of pH between 6.5 and 8.5, whilst curcuma-dyed polyamide shows a wider pH range: from 8.5 to 13.0. The stability of pH sensing to washing was evaluated. Three different kinds of washing agents were used in order to simulate the real life conditions of a garment or a cloth. Standard test methods were used when available for washing tests. The pH sensing of the curcuma-dyed fabrics demonstrated an excellent fastness to all kinds of washing. Ionic strength of the solution does not affect the color changes. Moreover, color reversibility of the fabrics was proven, too. Color change and reversibility of the fabrics was assessed by an UV-visible spectrophotometer. Spectral changes were observed at 540 nm for curcuma-dyed cotton, and at 487 and 574 nm for polyamide.

Removal of Cu(II) ions from water using thermally-treated horn–hoof powder as biosorbent

AbstractIn this work, thermally-treated “horn–hoof” powder was studied as biosorbent to remove copper (II) ions from aqueous solutions. Adsorption of copper onto horn–hoof powder was tested in batch process at different experimental conditions. The effect of the initial metal ion concentration, biosorbent dosage, contact time, pH and temperature were investigated with respect to the biosorption characteristics of Cu(II) ion on the horn–hoof powder. The biosorbent characterization was carried out by Fourier transform infrared spectroscopy, mini-cell electrophoresis, BET and particle sizing analysis. According to the tests, the adsorption equilibrium time was reached within 48 h and the optimum adsorption of Cu(II) ions took place at the pH value of 5.5. The Langmuir adsorption isotherm was successfully applied to the biosorption process of Cu(II) ions onto horn–hoof powder. The thermodynamic and kinetic data suggested that the biosorption process is an endothermic process involving chemical reactions and f...