Differentiating between Natural and Modified Cellulosic Fibres Using ATR-FTIR Spectroscopy

This paper presents the limitations and potential of ATR-FTIR spectroscopy applied to the study of cellulosic textile collections The technique helps to differentiate natural fibres according to the content of lignin, pectin, hemicellulose, and wax, although some problematic issues should be considered. The spectral differences derived from the environmental humidity uptake and the plant composition are reviewed and discussed in the light of new experimental data. Diagnostic bands are proposed that can discriminate between different fibres from different plants. The contribution of ageing is also considered, demonstrating that sometimes aged fibres cannot be reliably recognised. In contrast, the potential of ATR-FTIR spectroscopy to discriminate between natural and modified fibres is discussed and proven. The best results were obtained when microinvasive ATR-FTIR spectroscopy was coupled with SEM observations. The proposed protocol was tested on microsamples of various cellulosic materials from traditional Japanese samurai armours dating from the 16th to the 20th centuries (Morigi Collection, Museo delle Culture, Lugano, Switzerland). The results facilitated a complete characterisation of the materials and demonstrated that the protocol can be used to study a wide variety of cellulosic materials, including both natural and man-modified fibres, and paper

Prediction of in-plane stiffness properties of Non-Crimp Fabric laminates by means of 3D Finite Element analysis

Non-crimp fabric (NCF) composites are constituted by differently oriented layers of ideally unidirectional fibre tows. However, a slight waviness always appears in the tows. The applicability of the General Laminate Theory (GLT) to obtain the stiffness properties of NCF laminates is elucidated in this paper. For this purpose, a 3D finite element (FE) model of the representative unit cell (RUC) of a single NCF lamina has been carried out to obtain its apparent stiffness properties, which are employed, along with the GLT, to determine the stiffness properties of the laminate. These properties are compared with those obtained from the FE model of the RUC of the whole laminate for several configurations with different stacking sequences, fibre contents and crimp angles. Finally, predictions are compared with existing experimental results. The numerical results achieved validate the use of the GLT in NCF composites, once the lamina properties have been calculated taking into account the internal structure of these materials

Modelling the forming mechanics of engineering fabrics using a mutually constrained pantographic beam and membrane mesh

A method of combining 1-d and 2-d structural finite elements to capture the fundamental mechanical properties of engineering fabrics subject to finite strains is introduced. A mutually constrained pantographic beam and membrane mesh is presented and simple homogenisation theory is developed to relate the macro-scale properties of the mesh to the properties of the elements within the mesh. The theory shows that each of the macro-scale properties of the mesh can be independently controlled. An investigation into the performance of the technique is conducted using tensile, cantilever bending and uniaxial bias extension shear simulations. The simulations are first used to verify the accuracy of the homogenisation theory and then used to demonstrate the ability of the modelling approach in accurately predicting the shear force, shear kinematics and out-of-plane wrinkling behaviour of engineering fabrics

Regenerable Antibacterial Cotton Fabric by Plasma Treatment with Dimethylhydantoin: Antibacterial Activity against S. aureus

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La diversité ethnoculturelle dans le curriculum de sciences de l’Ontario, de la 1ère à la 12ème année

Dans sa politique antiraciste et d’équité ethnoculturelle de 1993, le gouvernement ontarien se propose de développer ou de modifier les programmes d’études afin qu’ils reflètent de façon équitable la diversité raciale et culturelle de la société. À l’instar du gouvernement, l’Ordre des enseignantes et des enseignants de l’Ontario appelle les enseignants à veiller à ce que les expériences d’apprentissage à l’école tiennent compte, de façon appropriée et équitable, de l’identité culturelle et raciale de tous les élèves. Notre étude cherche à mettre en lumière la place réservée à la diversité ethnoculturelle dans les programmes français de sciences et technologie de l’Ontario de la 1ère à la 12ème année grâce à une analyse qualitative des écrits sur l’éducation scientifique multiculturelle. Cette analyse tend à montrer que les programmes de sciences de l’Ontario, mis en vigueur respectivement en 1998, 1999 et 2000, laissent une place quasi négligeable à la diversité ethnoculturelle que ce soit dans leurs fondements, dans les attentes et les contenus d’apprentissage ainsi que dans les stratégies pédagogiques suggérées.In its 1993 antiracist and ethnocultural equity policy, the government of Ontario undertook to develop or modify school curriculums in order to reflect racial and cultural diversity in an equitable manner. The Ontario College of Teachers urged its members to keep in mind the cultural and racial identity of all students in an appropriate and equitable manner during all learning experiences in the school. This study addresses the place given to ethnocultural diversity in French science and technology programs in Ontario grades 1 to 12 through a literature review of official documents on multicultural science education. This qualitative analysis tends to show that in the science programs in Ontario implemented in 1998, 1999 and 2000 there is an almost negligible place given to ethnocultural diversity in their underpinnings, overall expectations, specific expectations and suggested instructional strategies

A progressive damage model of textile composites on meso-scale using finite element method: static damage analysis

A meso-scale finite element model for static damage in textile composites was established. The impregnated yarn is taken as homogeneous and transverse isotropic material, whose mechanical properties are calculated using Chamis' equations. The damage modes are determined by using the Tsai-Wu criterion and additional criteria. The Murakami damage tensor is used to calculate the post-damage stiffness matrix. The model has been validated using plain weave and twill weave carbon-epoxy composites. The initiation of inter-fiber matrix cracks and fiber rupture were analyzed using this meso-FE model

Embroidered metamaterial antenna for optimized performance on wearable applications

© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim In this work, an embroidered metamaterial monopole antenna based on a split ring resonator electromagnetic bandgap shielding structure is designed, simulated, and tested. This work investigates the impact of different types of embroidering metamaterial patterns on the antenna performance, shielding effect in terms of human safety through specific absorption rate analysis and degree of material wearability, in comparison with the standard antenna topologies. The proposed antenna design presents a full compact embroidered metamaterial device manufactured in felt textile substrate and requires a 85 × 70 mm2area, operating at 2.45 GHz. On-voxel analysis reveals that specific absorption standards are satisfied for both public and occupational sector with a significant safety margin whereas the antenna performance in terms of gain and directivity are significantly optimized with regard to standard wearable materials

Adsorbent Carbon Fabrics : New Generation Armour for Toxic Chemicals

Activated carbon in the form of a regular fabric obtained using viscose rayon precursor is a new generation adsorbent material having superior sorptional properties and is finding varied defence applications. Carbonisation and activation mechanisms and properties and applications of adsorbent carbort fibres made from viscose rayon precursor are reviewed in this paper

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