Evaluation of Effective Thermal Conductivities of Porous Textile Composites

An uncoupled multi-scale homogenization approach is used to estimate the effective thermal conductivities of plain weave C/C composites with a high degree of porosity. The geometrical complexity of the material system on individual scales is taken into account through the construction of a suitable representative volume element (RVE), a periodic unit cell, exploiting the information provided by the image analysis of a real composite system on every scale. Two different solution procedures are examined. The first one draws on the classical first order homogenization technique assuming steady state conditions and periodic distribution of the fluctuation part of the temperature field. The second approach is concerned with the solution of a transient flow problem. Although more complex, the latter approach allows for a detailed simulation of heat transfer in the porous system. Effective thermal conductivities of the laminate derived from both approaches through a consistent homogenization on individual scales are then compared with those obtained experimentally. A reasonably close agreement between individual results then promotes the use of the proposed multi-scale computational approach combined with the image analysis of real material systems.Comment: 17 pages, 7 figure

Thermo-physiological properties of 3D warp knitted spacer fabrics for car seat application

Thermal comfort properties of 3-Dimensional knitted spacer fabrics have been studied in order to replace the existingpolyurethane foams in the car seat and back supports. The influence of different characteristics of spacer fabrics, likestructure, areal density, thickness and density on thermo-physiological performance has been studied. The potential thermalbehavior is identified with the support of the thermal conductivity and resistance evaluation. The air and water vaporpermeability have been measured and analyzed in-order to study the breathable performance of spacer fabrics.Advance statistical evaluation and two-way analysis of variance is used to analyze the significance of various factors onrequired properties. The result shows that spacer fabric with a hexagonal net structure has more open structure on surfacethan lock knit fabrics, which results in highly permeable to air with good thermal conductivity. It is also observed that, thehexagonal net fabrics have the ability to pass more water vapor than the fabrics with lock knit structure on the surface.These findings are the important requirements for designing the car seats with required thermal comfort properties using3D spacer fabrics

Thermo-physiological properties of 3D warp knitted spacer fabrics for car seat application

475-485Thermal comfort properties of 3-Dimensional knitted spacer fabrics have been studied in order to replace the existing polyurethane foams in the car seat and back supports. The influence of different characteristics of spacer fabrics, like structure, areal density, thickness and density on thermo-physiological performance has been studied. The potential thermal behavior is identified with the support of the thermal conductivity and resistance evaluation. The air and water vapor permeability have been measured and analyzed in-order to study the breathable performance of spacer fabrics. Advance statistical evaluation and two-way analysis of variance is used to analyze the significance of various factors on required properties. The result shows that spacer fabric with a hexagonal net structure has more open structure on surface than lock knit fabrics, which results in highly permeable to air with good thermal conductivity. It is also observed that, the hexagonal net fabrics have the ability to pass more water vapor than the fabrics with lock knit structure on the surface. These findings are the important requirements for designing the car seats with required thermal comfort properties using 3D spacer fabrics

Copper-Treated Environmentally Friendly Antipathogenic Cotton Fabric with Modified Reactive Blue 4 Dye to Improve Its Antibacterial and Aesthetic Properties

The objectives of the present study were to develop an environmentally friendly, low-price, easy, and fast method for developing antipathogenic (antibacterial, antifungal, and antiviral) cuprous-oxide-coated multifunctional fabrics. The fabrics were first sensitized with citric acid, and then Cu2O particles were formed using the Fehling solution method. The cuprous oxide particles were then applied to the cotton fabrics. To create the Cu2O particles, three different kinds of reducing agents with varying concentrations were used. SEM, dynamic light scattering, FTIR, EDS, and XRD were used to examine the surface morphologies and metal presences. In the second step, a reactive antibacterial dye was made (by reacting Reactive Blue 4 with triclosan). The molecular structure of the modified dye was confirmed with FTIR. The resultant antibacterial dye was applied on the copper-treated cotton fabrics in accordance with the exhaust dyeing protocol. The dyed fabrics were characterized through the colorimetric data (L*, a*, b*, C, H, and K/S), levelness of dye, fastness properties as well as exhaustion and fixation rates. Cuprous-oxide-coated fabrics were tested for antipathogenic activity using quantitative and qualitative measurement results. The fabrics treated with cuprous oxide particles reduced with sodium hydrosulfite at 1 g/L seemed to have the highest antipathogenic effect. Moreover, the versatility of the hygienically developed bioactive fabrics in terms of their comfort properties such as air permeability and stiffness were investigated. Finally, the coating’s durability was confirmed by evaluating its antibacterial properties and performing an SEM analysis after laundry