Searching for natural conductive fibrous structures via a green sustainable approach based on jute fibers and silver nanoparticles

This paper provides new insights regarding jute fibers functionalization with silver nanoparticles (Ag NPs) with improved conductivity values and highlights the sustainability of the processes involved. These NPs were applied onto jute fabrics by two different sustainable methods: ultraviolet (UV) photoreduction and by using polyethylene glycol (PEG) as a reducing agent and stabilizer. Field Emission Scanning Electron Microscopy (FESEM) images demonstrated that the Ag NPs were incorporated on the jute fibers surface by the two different approaches, with sizes ranging from 70 to 100 nm. Diffuse reflectance spectra revealed the plasmon absorption band, corresponding to the formation of metallic Ag NPs, in all samples under study. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) was used to characterize the obtained samples, demonstrating NPs adsorption to the surface of the fibers. The resistivity value obtained by the two-point probe method of the jute fabric without functionalization is about 1.5 × 107 Ω·m, whereas, after NPs functionalization, it decreased almost 15,000 times, reaching a value of 1.0 × 103 Ω·m. Further research work is being undertaken for improving these values, however, 1000 Ω·m of resistivity (conductivity = 0.001 S/m) is already a very reasonable value when compared with those obtained with other developed systems based on natural fibers. In summary, this work shows that the use of very simple methodologies enabled the functionalization of jute fibers with reasonable values of conductivity. This achievement has a huge potential for use in smart textile composites.The authors are thankful to TSSiPRO project, operation code NORTE 01-0145-FEDER-000015, supportedbythe“ProgramaOperacionalRegionaldoNorte”numberNORTE-45-2015-02andtheFCT(Portuguese Science Foundation) for Armando Ferreira grant: SFRH/BPD/102402/2014. Pedro Souto and Vitor Gomes are acknowledged for performing the jute fabric corona treatment.info:eu-repo/semantics/publishedVersio

Functionalization of Bacterial Cellulose With Bacterial Pigments: Optimization Using a Full Factorial Design Approach

Pigments from natural sources, such as bacterial pigments, have gained increased attention in recent years due to their biodegradability, non-toxicity, and noncarcinogenicity. The intention to replace synthetic and oil-derived compounds is not restricted to synthetic dyes; other applications include the replacement of oilderived polymers for more environmentally friendly options, such as biopolymers. In this work, the functionalization of a bacterial cellulose (BC) biopolymer with bacterial pigments was explored using a full factorial design methodology to evaluate the best functionalization conditions to produce colored BC. From the factors and interactions evaluated, it was possible to conclude that the variable duration of the functionalization procedure could be reduced to a low level without significantly affecting the functionalization of the BC samples with bacterial pigments. Moreover, BC is a product with high industrial applicability, versatility, and sustainability. Hence, the multifunctional colored BC can be applied in the packaging, paper, and textile industries, among others. Keywords: bacterial pigments, bacterial cellulose, full-factorial design, optimizatio

Agrimonia Eupatoria L.-Incorporated Electrospun Nanofibers and Cotton Composite for Antibacterial Wound Dressing Applications

Composite wound dressings which combine the suitable properties of distinct materials into one dressing are currently being explored, in combination with different types of bioactive compounds, to enhance the healing process and avoid skin infections. In the present work, poly(vinyl alcohol) and chitosan nanofibers containing Agrimonia eupatoria L. were fabricated using a needleless electrospinning method (through Nanospider technology) and deposited on top of a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cotton textile dressing. The negatively charged carboxyl groups on the cotton fibers interacted with the positively charged amino groups of chitosan, which was previously blended with poly(vinyl alcohol) and Agrimonia eupatoria L. to produce the nanofiber layer. The properties of the produced composite materials were analyzed to determine the dressing’s potential for antimicrobial wound dressing applications. Keywords: cotton, textile dressing, electrospun nanofibers, Agrimonia eupatoria L., antibacterial composite wound dressing

Surface modification of natural fibers: a review

"International Symposium on "Novel Structural Skins: Improving sustainability and efficiency through new structural textile materials and designs - TensiNet Association and the Cost Action TU1303"In recent years there have been several attempts to replace synthetic fibers with natural fibers in fiber reinforced composites, due to increasing environmental awareness and depletion of oil resources. The fact that natural fibers are available cheaply and in abundance, being biodegradable and low density, has motivated many researchers throughout the world to explore their application potential in various industrial sectors. However, natural fibres also have some limitations such as high moisture absorption and subsequent swelling and degradation, poor chemical and fire resistance, high dispersion of mechanical properties, poor interfacial interactions with polymeric or cementitious matrices, etc. Therefore, there is a huge concern to modify the surface of natural fibers through various techniques, in order to overcome their inherent drawbacks and to successfully utilize these materials in various applications. This paper presents a review of existing research studies focused on the surface treatment of natural fibers and the use of nanocelulose, a natural nanofiber, for their application in composite materials

Conductive Thermoplastic Starch (TPS) Composite Filled with Waste Iron Filings

A thermoplastic starch (TPS) was produced, starting with potato starch, glycerol and acetic acid, to shape it in films of thickness around 100 microns. To TPS iron waste filing particles, in the amount of 12% the weight of starch, were introduced in different modalities: as received, reduced in size by the use of a mortar, after treatment with hydrochloric acid, and after treatment and removal of hydrochloric acid. Morphological studies were carried out by optical and scanning electron microscopy and illustrated that the dispersion of iron filings was not optimal, though some improvement was observed by a reduced dimension of the particles. Tensile tests indicated the considerable improvement of stiffness offered by the insertion of iron particles to TPS, although the ultimate strain was reduced to less than 10%. Thermal characterization using thermogravimetry allowed revealing the three typical peaks for potato starch degradation, with only a slight decrease due to iron introduction. EDS allowed evaluating the presence of impurities in the iron filings and evidenced that the presence of iron was more effective on the surface than in the rest of the film. As a final consideration, An improvement in electrical conductivity by over an order of magnitude was obtained by the TPS+Fe+HCl film with respect to pure TPS

Textile waste fiber-reinforced mortar: performance evaluation

Trabalho apresentado em 1st International AFRICA Sustainable Waste Management Conference, 23-25 July 2012, Lobito, AngolaApresentação oral - Resumo alargad

Ultra-sensitive affordable cementitious composite with high mechanical and microstructural performances by hybrid CNT/GNP

In this paper a hybrid combination of carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) was used for developing cementitious self-sensing composite with high mechanical, microstructural and durability performances. The mixture of these two nanoparticles with different 1D and 2D geometrical shapes can reduce the percolation threshold to a certain amount which can avoid agglomeration formation and also reinforce the microstructure due to percolation and electron quantum tunneling amplification. In this route, different concentrations of CNT + GNP were dispersed by Pluronic F-127 and tributyl phosphate (TBP) with 3 h sonication at 40 °C and incorporated into the cementitious mortar. Mechanical, microstructural, and durability of the reinforced mortar were investigated by various tests in different hydration periods (7, 28, and 90 days). Additionally, the piezoresistivity behavior of specimens was also evaluated by the four-probe method under flexural and compression cyclic loading. Results demonstrated that hybrid CNT + GNP can significantly improve mechanical and microstructural properties of cementitious composite by filler function, bridging cracks, and increasing hydration rate mechanisms. CNT + GNP intruded specimens also showed higher resistance against climatic cycle tests. Generally, the trend of all results demonstrates an optimal concentration of CNT (0.25%) + GNP (0.25%). Furthermore, increasing CNT + GNP concentration leads to sharp changes in electrical resistivity of reinforced specimens under small variation of strain achieving high gauge factor in both flexural and compression loading modes.This research was funded by European Commission-Shiff2Rail Program under the project“IN2TRACK2–826255-H2020-S2RJU-2018/H2020-S2RJU CFM-2018

Mechanical properties of composite materials made of 3D stitched woven-knitted preforms

This article presents an experimental investigation carried out to understand the mechanical behavior of composite materials made of 3D stitched woven-knitted basalt fabrics. The innovative preforms used consist of two outer layers of a plain woven fabric combined with two inner layers of weft-knitted fabrics. The weft-knitted fabrics selected for the study were varied plain knit, 1 × 1 rib, Milano, and interlock. The fabric layers were stitched together with Kevlar yarns. These 3D stitched preforms were impregnated with polyester resin using resin transfer molding, and the corresponding composites obtained were tested under tensile, bending, and impact loads. The results obtained show that the type of knitted structure significantly influences the mechanical performance of the 3D stitched woven-knitted composites. The composite using interlock structure as the inner layers has the best results concerning energy absorption and tensile strength. The varied plain knit structure has proved to be the best suited to impart stiffness as it provides the highest Young’s modulus among the above four knitted structures.The authors wish to thank the European Commission for awarding research funds under the EU Asia-link program (Project No. 82158), the University of Minho in Portugal and Donghua University in China, for providing research facilities

Chitosan/nanocellulose electrospun fibers with enhanced antibacterial and antifungal activity for wound dressing applications

The combination of biodegradable fibers at nanoscale with plant-based extracts is attracting increasing attention to produce wound dressing systems. In this work, nanofibers based on chitosan (CS), poly(ethylene oxide) (PEO), cellulose nanocrystals (CNC) and acacia plant-based extract were developed by electrospinning. Firstly, the polymeric formulations and electrospinning parameters were optimized, resulting in nanofibers with average diameters of 80 nm. CNC were successfully introduced into the optimized CS/PEO blend and the membranes were characterized by FESEM, ATR-FTIR, TGA, XRD, WVTR and WCA. The CNC incorporation improved the nanofibers' physical integrity, morphology, diameters, water vapor transmission rate and thermal properties. After acacia introduction into the best CS/PEO/CNC system, the antibacterial effect was relatively maintained while the antifungal activity was enhanced for some fungi, demonstrating its great effect against a wide range of microorganisms, which is crucial to prevent or treat infections. All the developed systems exhibited absence of cytotoxicity in non-tumor cells, suggesting their biocompatibility. Finally, a continuous release of the acacia extract was observed for 24 h, showing its prolonged action, which contributes to the healing process while reduces the frequency of dressing's replacement. Overall, the developed nanofibers are very promising to act as localized drug delivery systems for wound care applications.The authors are thankful to TSSiPRO project, operation code NORTE01-0145-FEDER-000015. The authors are also grateful to FCT, Portugal for financial support through national funds FCT/MCTES to CIMO (UIDB/00690/2020) and to 2C2T (UID/CTM/00264/2019). D. P. Ferreira thank the national funding by FCT through the individual scientific employment program-contract (CEECIND/02803/2017), S. M. Costa thank the FCT PhD Scholarship (SFRH/BD/147517/2019), and L. Barros and R. Calhelha thank the institutional scientific employment program-contract. This work has been supported by the Ministry of Education, Science and Technological Development of Republic of Serbia (451-03-68/2020-14/200007).CEECIND/02803/2017SFRH/BD/147517/2019info:eu-repo/semantics/publishedVersio

Coated chitosan onto gauze to efficient conditions for maintenance of the wound microenvironment

The aim of this work was to evaluate the thermo-physiological comfort and moisture properties of surgical cotton gauze coated with chitosan (CH). Gauze was coated with CH at mass fractions of 0.5, 0.25, 0.125, 0.1, 0.063 wt%. Thermal, moisture management and morphological properties were evaluated. Results indicate that the functionalized medical gauze induces low capilarity, allowing a good degree of moisture and absorption capacity of wound exudates. This biofunctional medical gauze coated with CH0,125 wt% demonstrates to deliver an efficient coating and promote the best conditions for maintenance of the wound microenvironment.Jefferson Souza acknowledge CAPES Foundation, the Ministry of Education of Brazil, Proc. no 8976/13-9 and the Department of Textile Engineering of the University of Minho, Portugal. Andrea Zille acknowledges funding from FCT within the scope of the project POCI-01- 0145-FEDER-007136 and UID/CTM/00264. This work is financed by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007136.info:eu-repo/semantics/publishedVersio