Alfredo Calvimontes

Effects of Topographic Structure on Wettability of Differently Woven Fabrics

Optical analysis of roughness operating on the principle of chromatic aberration and dynamic wetting measurements have been used to investigate the surface properties of polyester fabrics with different woven structures. The results revealed differences in the two basic types of weave — plain and twill — with respect to the penetration behavior of water. Additionally, plain weave fabrics were manufactured using differently profiled fibers — round and cruciform. It was established that fabrics composed of fibers having a cruciform cross section are more hydrophobic than those that are round. It was shown that topographical characteristics of the fabrics strongly depend on their construction parameters such as the type and fineness of filaments, yarn fineness, yarn density, and, consequently, the type of weave. The results provide further insight into the relationship between construction parameters of fabrics of the same chemical nature and their topographic and wetting properties.

Elastic magnetic sensor with isotropic sensitivity for in-flow detection of magnetic objects

We present a conceptually new approach for the detection of magnetic objects flowing through a fluidic channel. We produce an elastic and stretchable magnetic sensor and wrap it around capillary tubing. Thus, the stray fields induced by the flowing magnetic objects can be detected virtually in all directions (isotropic sensitivity), which is unique for elastic sensors when compared to their rigid planar counterparts.

Advances in Topographic Characterization of Textile Materials

All textile materials, having periodic surfaces, show horizontal and vertical repetitive unities. For this reason, different length scales have to be taken into account by interpreting topographic data measured. In this study, a topographical characterization method for textile materials at different length scales is presented and justified. The topographical study of textile materials using different length scales permits us to characterize the surfaces considering their specific morphologies due to the type of weave, yarn and filament/ fibers separately. The use of a scale concept to characterize textile surfaces seems to be a new skill that helps to correlate textile parameters, topography, and topographical changes with interface phenomena such as spreading, wetting, capillary penetration, and soil release.

Innovative sol-gel route in neutral hydroalcoholic condition to obtain antibacterial cotton finishing by zinc precursor

In the present study, a possibility to realize a transparent sol by zinc-based precursors in a neutral medium without acidic or alkaline catalyst was investigated. Moreover, to study the influence of an inorganic–organic hybrid polymer on the proposed antibacterial finishing, the Zn-based sol was mixed with 3-glycidoxypropyltrimethoxysilane (GPTMS), a hybrid sol–gel precursor, to produce zinc-containing silica coatings on the cotton fibres. An optimization of functionalization process parameters was performed by monitoring survival rate of Escherichia coli bacteria. Finally, selected finishes were tested in respect to their antibacterial activity using potential pathogenic bacteria Staphylococcus aureus and Klebsiella pneumoniae. Sol–gel synthesized cotton finishes based on nano-Zn acetate without and with GPTMS showed larger bactericidal and bacteriostatic activities. The both types of finishes also show hydrophobic effect within the first eliminates the hydrophobicity effect and reduces antibacterial activity. The results are very promising, since the antibacterial activity of cotton is comparably high and the finishing procedure is cheap and can be easily performed.

Surface roughness and wettability of wool fabrics loaded with silver nanoparticles: Influence of synthesis and application methods

Hydrophilization of wool fabrics was performed by silver nanoparticles with different surface charge using three different methods: exhausting, pad–dry–cure and in situ synthesis. Dynamic wetting measurements and surface topography analysis were used to evaluate surface changes on wool fabrics. The wool samples in situ loaded revealed the highest fabric roughness and porosity, while the use of the pad–dry–cure method leads to the lowest fabric porosity, and its roughness values approximately were the same as those for samples loaded with the exhaustion method. The results revealed that loading silver nanoparticles with high surface charges onto wool fabrics via the exhaustion method can significantly improve the hydrophilicity of wool fibre surface. The possible reasons for this improvement are discussed.

Effect of Cellulase Enzyme on Cellulose Nano-topography

Abstract In this study, modification effects of cellulose foil by cellulase enzyme are studied in respect to topography changes by means of atomic force microscopy (AFM). The results provide useful information to understand the enzyme action in the amorphous and crystalline regions of cellulose. It was revealed, that the treatment of cellulose with the cellulase enzyme depends on its concentration, which selectively attacks amorphous cellulose regions. At lower concentration, a random surface roughening of the cellulose foil was observed. With increasing enzyme concentration, the cellulose surface became smoother. On the basis of this knowledge, a conceptual model to describe the conditioning effect by cellulase on the cleanability of cotton fabrics was developed. With the help of this model, we are able to estimate changes in the nanoporosity of cotton fibres.

Effects of Oxygen Plasma Treatment on the Physical and Chemical Properties of Wool Fiber Surface

The aim of this study was to evaluate the effect of oxygen plasma treatment on the surface roughness, morphology, chemical surface structure, crystallinity and tensile properties of wool fiber yarn. The wool fibers were treated with oxygen plasma at a different treatment time. The morphological surface characterization of wool fibers was realized at sub-micro scale by means of high-resolution scandisk confocal microscopy and scanning electron microscopy. The chemical structure of untreated and plasma treated wool fiber surface was analyzed by Attenuated Total Reflectance Fourier Transform Infrared spectrometry. In addition, the percentage of crystallinity and the size of the crystals were investigated using an X-ray diffractometer. The results showed that oxygen plasma treatment leads to the removal of surface lipids and oxidizes the cysteine in the exocuticle and increases the surface roughness.

Influence of the Cross-sectional Geometry on Wettability and Cleanability of Polyester Woven Fabrics

Abstract Filament cross-sections used in textiles and composites are becoming more and more complex. The type of cross-sectional shape impacts filament properties and are therefore, yarn and fabric characteristics. In this paper, the influence of different filament cross-section geometry on fibre properties as well as on fabric surface characteristics was studied. PET (polyethylene terephthalate) filament yarns made from two different cross-sectional shaped filaments, round and cruciform, were manufactured by the melt spinning process. Polyester fabrics were manufactured in a needle band weave machine from these two types of filament yarns. Topographic characteristics of polyester fabrics manufactured were determined by an imaging instrument for optical roughness analysis based on the principle of chromatic aberration. Differences between soiling behaviour, cleanability and wettability of the fabrics were revealed and discussed.

Generation of micro-sized conductive lines on glass fibre fabrics by inkjet printing

Micro-sized lines were inkjet printed on glass fibre fabrics using different droplet spacing. A conductive ink containing silver nanoparticles was used in this study. Glass fibre fabrics were differently pre-treated to avoid spontaneous spreading of the ink dispersion. The sample topography was examined using scanning electron, optical and confocal microscopy with a chromatic sensor. Printability conditions were discussed based on the results of topographic characterization and wettability measurements.

Volumetrical Characterization of Sheet Molding Compounds

For a comprehensive study of Sheet Molding Compound (SMC) surfaces, topographical data obtained by chromatic confocal imaging were submitted systematically for the development of a profile model to understand the formation of cavities on the surface. In order to qualify SMC surfaces and to predict their coatability, a characterization of cavities is applied. To quantify the effect of surface modification treatments, a new parameter (Surface Relative Smooth) is presented, applied and probed. The parameter proposed can be used for any surface modification of any solid material.