António Pedro Souto

Polymer Nanocomposites for Multifunctional Finishing of Textiles – A Review

Improvement of existing properties and the creation of new material properties are the most important reasons for the functionalization of textiles. Polymer nanocomposites offer the possibility of developing a new class of nanofinishing materials for textiles with their own manifold of structure property relationship only indirectly related to their components and their micron and macro-scale composite counterparts. Though polymer nanocomposites with inorganic filler of different dimensionality and chemistry are possible, efforts have only begun to uncover the wealth of possibilities of these new materials. Approaches to modify the polymer nanocomposite system by various inorganic or organic substances can lead to a huge number of additional functionalities which are increasingly demanded by the textile industries. In this review, we have compiled the current research in polymer nanocomposite-based nanofinishes for multifunctional textiles which provides a snapshot of the current experimental and theoretical tools being used to advance our understanding of polymer nanocomposites and their applications in textiles.

Application of nanotechnology in antimicrobial finishing of biomedical textiles

In recent years, the antimicrobial nanofinishing of biomedical textiles has become a very active, high-growth research field, assuming great importance among all available material surface modifications in the textile industry. This review offers the opportunity to update and critically discuss the latest advances and applications in this field. The survey suggests an emerging new paradigm in the production and distribution of nanoparticles for biomedical textile applications based on non-toxic renewable biopolymers such as chitosan, alginate and starch. Moreover, a relationship among metal and metal oxide nanoparticle (NP) size, its concentration on the fabric, and the antimicrobial activity exists, allowing the optimization of antimicrobial functionality.

Surface Modification of Banana Fibers by DBD Plasma Treatment

Banana fibers, an environmentally friendly raw material freely available, were physically modified by atmospheric dielectric barrier discharge (DBD) plasma treatment of different dosages. The influence of the plasma treatment applied on the banana fibers was performed considering the mechanical properties, wettability, chemical composition and surface morphology. These properties were evaluated by tensile tests, static and dynamic contact angle, Fourier transform infrared spectroscopy, energy dispersive spectroscopy, X-ray diffractometry, conductivity and pH of aqueous extract, differential scanning calorimetry and scanning electron microscopy images. We compare untreated and treated fibers with three different DBD plasma dosages. The results of this study showed considerable modifications in banana fibers when these are submitted to plasma treatment.

A study on the dynamics of a study on the dynamics of spatial mechanisms with frictional spherical clearance joints

The first author expresses his gratitude to the Portuguese Foundation for Science and Technology through the PhD grant (PD/BD/114154/2016). This work has been supported by the Portuguese Foundation for Science and Technology with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalizacao (POCI) with the reference project POCI-01-0145-FEDER-006941.

Surface Modification on Polyamide 6.6 with Double Barrier Discharge (DBD) Plasma to Optimise Dyeing Process by Direct Dyes

Dyeing of polyamide fibers is normally made with acid dyes, however, it is somewhat difficult to achieve uniformity and control of pH and temperature must be carefully made. The possibility to dye polyamide 6.6 in a larger gamut of colours with good properties may be achieved using other classes of dyes after plasmatic modifications in textile substrates. Polyamide 6.6 fabrics were treated with Double Barrier Discharge (DBD) plasma obtained at atmospheric conditions in a semi-industrial machine and very positive results were obtained when dyeing is made with direct dyes. Surface modifications were evaluated, namely, roughness in terms of Atomic Force Microscopy, changes in chemical composition by X-Ray Photoelectron Spectroscopy (XPS) and microstructural analysis by SEM. In order to optimize dyeing process, different dye concentrations, pH and temperatures were attempted on dyeing with DBD treated fabrics. Important parameters were studied such as exhaustion, colour strength (K/S) and washing fastness. Chemical and physical effects of plasmatic discharge contribute to excellent results obtained in yield, exhaustion and fastness of dyeing of polyamide with direct dyes demonstrating extensive improvement of dye exhaustion from baths, easily achieving 100% in shorter dyeing times. These results mean less dyes in effluents and less time for dyeing processes. The cleanness of the processes and lower cost of direct dyeing are additional advantages when compared to difficulties in acidic dyeing of polyamide.

Preparation of cotton materials using CORONA discharge

Abstract The present work concerns the study of preparation processes when this operation is preceded by a CORONA discharge made on dry raw fabrics. The influence in the whiteness degree, hydrophility, starch removal and uniformity of properties of the cellulosic material after preparation is studied. Combined preparation processes are widely used in order to replace solutions where desizing, alkaline boiling and bleaching are individual operations, being a main interest to find the optimal conditions to achieve alkaline oxidative treatments with an uniform and more intense cleaning action. CORONA discharge is able to strongly modify hydrophility of cotton fabrics in raw stage, which is determinant to increase liquids absorption and uniformity of processed fabrics. Results of long-bath, pad-roll, pad-batch and pad-steam bleaching processes in laboratory conditions are compared using or not wetting agent in the recipes and including CORONA discharge as a preparation operation. The transfer of this technology to industry regarding the implementation in textile plant in a very near future is being worked, supported by results as the present ones.

Glycerol/PEDOT:PSS coated woven fabric as a flexible heating element on textiles

A polyamide 6,6 (PA66) fabric pre-treated with a double barrier dielectric (DBD) atmospheric plasma in air was coated with 1 and 5 layers of an intrinsically conducting glycerol-doped PEDOT:PSS polymer (PEDOT:PSS + GLY) with the final objective of developing a cost-competitive and temperature controllable flexible-heating element to be used in clothing encapsulated between an outer and an inner separator layer in order to provide heat-reflecting properties and uniform temperature distribution, respectively. FTIR, DSC, TGA, SEM, EDS, XRD and DMA analyses show significant changes in morphology, chemistry, enthalpy, crystallinity and glass transition temperature confirming that PEDOT:PSS and glycerol are not only spread over the PA66 yarn surfaces but are dispersed in the bulk facilitating relaxation and increasing structure and chain flexibility. Electrochemical and electrical resistivity (ρ) measurements confirm that the plasma treated PA66 coated with 5 layers of PEDOT:PSS + GLY presents the highest stability, resistance and capacitive behaviour, and the best capability of storing electrical energy. This configuration needs only 7.5 V to induce a temperature change up to 38 °C at a current density of 0.3 A g−1. The desired temperature is easily adjustable as a function of the applied voltage and by the number of coated layers of PEDOT:PSS + GLY. Despite the need to improve the uniformity of the coating thickness on the fabric for uniform heat generation, the observed results are quite impressive since they can be compared to the temperature obtained in carbon nanotube composites using similar voltages. This cost-competitive, safe, highly flexible and stable thermoelectric fabric has potential for use in large area textiles as a heating element in a wide range of applications such as garments, carpets, blankets and automotive seats.

Poliamid Boyama İşleminde DBD Plazma Modifikasyonunun Etkisi

In this work, a study of the dyeing of polyamide fabrics after surface modification by dielectric barrier discharge (DBD) plasma treatment was performed. Physical and chemical properties of the textile substrate were characterized before and after plasmatic modification, showing important changes in water contact angle, hydrophility, chemical surface composition and morphology. Dyeing properties with direct dyes were evaluated by means of dyebath exhaustion, color strength and washing fastness tests, demonstrating that plasma treated fabrics can achieve excellent dye uptake, high rate of dyeing and good uniformity, good fastness levels, meaning a great challenge and opportunity for industrial application.

Reactive pad-batch dyeing in CORONA discharged fabrics

Abstract The present work aims to the study of the increase of pick-up, together with uniformity degree, concerning the application of reactive dyeing baths by padding in a dry cotton fabric previously treated with CORONA discharge. Dyeing recipes, with and without wetting agent, are compared and advantages of CORONA discharge are analysed. Reactive dyes are used, expecting also to increase washing fastness of the difficult dark colours due to higher penetration of the dye into the core of the fibres when submitted to plasmatic treatment. The use of CORONA discharge intends to modify hydrophility of cotton fabrics even when they are presented to padding in hydrophobic state. A good alternative to wetting agent presence in recipes is found and more uniform and intense dyeings are performed in all cases.

Exploring geometric morphology in shape memory textiles: design of dynamic light filters

Thermo-responsive Shape Memory Alloys are able to adopt a temporary configuration and return to their programmed shape when heated to a determined activation temperature. The possibility to integrate them in textile substrates creates potential to develop smart textiles whose shape change explores functional and expressive purposes. The aim of this research is to develop shape memory woven textiles in which dynamic behavior achieves predefined geometric shapes. The requirement of geometric morphology was addressed through origami techniques. Combining foldability properties with shape change, it is possible to design textile structures with a variable number of layers. Difference in light transmittance is analyzed according to layer variation. Experiments conducted explore methodological processes aimed at future developments in dynamic light filters research. The results highlight a process to design textiles with predefined geometric morphologies that can be activated electrically, and delineate a further study in order to improve the shape memory textile behavior.