Eric Devaux

Flammability of polyamide-6/clay hybrid nanocomposite textiles

The flammability of polyamide-6 (PA-6)/clay nanocomposites used as textile fabrics has been investigated. PA-6/clay nanocomposite (PA-6nano) was prepared by melt blending and had an exfoliated structure. TG curves suggest that PA-6 is slightly stabilised between 450 and 600 °C. PA-6nano was processed via melt spinning to make multifilament yarns. Textiles have been evaluated as knitted fabrics and it is shown that the heat release rate of PA-6nano evaluated with the cone calorimeter at 35 kW/m2 is reduced by 40% in comparison with pure PA-6. This result offers a new promising route for flame retarding textiles with a permanent effect (laundry resistance) at relatively low cost and keeping the basic properties of the textiles.

High-Performance Polylactide/ZnO Nanocomposites Designed for Films and Fibers with Special End-Use Properties

Metallic oxides have been successfully investigated for the recycling of polylactide (PLA) via catalyzed unzipping depolymerization allowing for the selective recovery of lactide monomer. In this contribution, a metallic oxide nanofiller, that is, ZnO, has been dispersed into PLA without detrimental polyester degradation yielding PLA/ZnO nanocomposites directly suitable for producing films and fibers. The nanocomposites were produced by melt-blending two different grades of PLA with untreated ZnO and surface-treated ZnO nanoparticles. The surface treatment by silanization proved to be necessary for avoiding the decrease in molecular weight and thermal and mechanical properties of the filled polyester matrix. Silane-treated ZnO nanoparticles yielded nanocomposites characterized by good mechanical performances (tensile strength in the interval from 55 to 65 MPa), improved thermal stability, and fine nanofiller dispersion, as evidenced by microscopy investigations. PLA/ZnO nanocomposites were further extruded in films and fibers, respectively, characterized by anti-UV and antibacterial properties.

Evaluation of thermal and moisture management properties on knitted fabrics and comparison with a physiological model in warm conditions

This study reports on an experimental investigation of physical properties on the textile thermal comfort. Textile properties, such as thickness, relative porosity, air permeability, moisture regain, thermal conductivity, drying time and water-vapour transmission rate have been considered and correlated to the thermal and vapour resistance, permeability index, thermal effusivity and moisture management capability in order to determine the overall comfort performance of underwear fabrics. The results suggested that the fibre type, together with moisture regain and knitted structure characteristics appeared to affect some comfort-related properties of the fabrics. Additionally, thermal sensations, temperature and skin wetness predicted by Caseto® software for three distinct activity levels were investigated. Results show that the data obtained from this model in transient state are correlated to the thermal conductivity for the temperature and to Ret, moisture regain and drying time for the skin wetness. This provides potential information to determine the end uses of these fabrics according to the selected activity level.

Development of Phase Change Materials in Clothing Part I: Formulation of Microencapsulated Phase Change

Microcapsules containing phase change material for textile thermal insulation were synthesized and characterized. Prior to the encapsulation, the formation, the stability and phase change behavior of paraffin mixture were studied to define an optimum formulation with a wide temperature range. The addition of approximately 4 wt-% tetraethyl orthosilicate in n-hexadecane-n-eicosane mixture was found to improve latent heat of phase change. Microcapsules with approximately 70 wt-% paraffin in core material were investigated by using Fourier transform infrared spectroscopy, differential scanning calorimetry, thermal gravimetric analysis, and scanning electron microscopy.

Processing and characterization of conductive yarns by coating or bulk treatment for smart textile applications

The use of intelligent materials reacting to external stimuli is rapidly growing in the field of technical textiles. In this paper, the processing of conductive yarns for the development of smart textiles is discussed. Two different methods are exposed: the coating of textile yarns using conductive polymers, and the bulk treatment of spinnable polymers by conductive nanofillers. In the first part of this article, polyaniline (PANI)-coated ultra-high-molecular-weight polyethylene (UHMWPE, Dyneema®) yarns were prepared. Their electrical, morphological and electro-mechanical properties including the temperature influence were investigated. Power handling of PANI-coated conductive yarns as a function of the current was also evaluated. Three different prototypes of conductive multiple yarns have been proposed. In the second part, the use of multi-walled carbon nanotubes as reinforcing conductive nanofiller for spinnable polymers has been studied. The major influence of the homogeneous dispersion of the nanotubes in the host matrix is particularly pointed out, and the electrical behaviour of the nanocomposite yarns has been investigated. Different conductive yarns, developed in our laboratory, are expected to be used as fibrous sensors, connection elements in smart clothing, electro-mechanical or thermal data acquisition devices and conductive fabrics for electromagnetic shielding applications.

Application of Contact Angle Measurement to the Manufacture of Textiles Containing Microcapsules

The efficiency of a binder to link microcapsules on a textile surface depends on the compatibility of the different interfaces of the products involved in the coating process. The choice of a binder adapted to the microcapsules was determined in this study by the comparison of the surface energy components induced by the contact angle measurement method and washing tests. It was found that a polyurethane-based binder was the most suitable to link melamine formaldehyde microcapsules. Furthermore, the adhesion of microcapsules was closely dependent on the chemical nature and structure of the textile support.

Thermal and mechanical characteristics of polylactide filaments drawn at different temperatures

Abstract Polylactide (PLA) filaments produced by melt spin-drawing in different conditions (draw ratio, temperature of the draw roll) have been studied to demonstrate the influence of the process conditions on the tensile properties of the PLA filaments. Draw ratio varies from 2 to 3.5 and temperature of the draw roll from 80°C to 120°C. The thermal characteristics have been investigated using modulated differential scanning calorimetry (MDSC) and crystallinity using X-Ray Diffraction (XRD). Shrinkage of PLA multifilaments depending on the processing conditions is also investigated. It is demonstrated that the temperature of the draw roll is essential to obtain PLA filaments with optimum properties. At 80°C, the size of the lamellar crystals, measured using DRX, is not the highest. It is necessary to set the temperature of the draw roll at 110°C to obtain thick lamellar crystals. So, in those conditions, the PLA filaments have their optimum mechanical properties.

Electrokinetic approach of adhesion between polyester fibres and latex matrices

Abstract The adhesive interaction between salt-treated polyester fibres and elastomeric matrices has been studied. Two types of approaches have been used to predict the impact of the salt treatment on the interaction between both jointing partners. First of all ξ -potential measurements have been used to characterize the interactions between fibre and matrix. Changes in the surface composition of salt-treated fibres were investigated by electrokinetic measurements using the streaming potential. Zeta potential of latex were determined using the electrophoresis method. The second approach is the characterization of adhesion by the interfacial shear strength determined from the single-fibre pull out test. We compared results issued from the two methods used during this study.

Characterization of interfacial adhesion in a ultra-high-molecular-weight polyethylene reinforced polydicyclopentadiene composite

The possibility of using ultra-high-molecular-weight polyethylene fibres as reinforcing material for a polydicyclopentadiene matrix has been studied. The adhesion between the thermosetting matrix and the reinforcing fibres has been measured using a micromechanical test derived from the pull-out test. The results show that the maximum shear stress reaches 28 MPa, and confirm that strong interactions are established between the two materials. These results are interpreted in terms of compatibility between the molecular structures of the different polymers. The exothermy observed during the matrix polymerization enables entanglement of the constitutive macromolecules of polyethylene and of polydicyclopentadiene in the vicinity of the interface.

Electrical and mechanical properties of phenoxy/multiwalled carbon nanotubes multifilament yarn processed by melt spinning:

Nanocomposites based on Poly ((hydroxy ether) of bisphenol A) (Phenoxy) filled with multiwalled carbon nanotubes has been prepared by extrusion. Rheological behaviour and thermal degradation of these nanocomposites have been studied by melt flow index and thermogravimetric analysis. The results show that the addition of carbon nanotubes up to 2wt% increases the viscosity but does not modify significantly the spinnability of the compounds. Moreover, incorporation of these nanofillers allows an improvement of the thermal decomposition. In a second step, these nanocomposites have been processed by melt spinning to produce multifilament yarn. Transmission electron microscopy observations have been done to study carbon nanotubes dispersion and orientation. Nanocomposite morphology correlated with electrical measurements reveal an electrical percolation around 1.5 wt.% without decreasing significantly mechanical properties.