Maryline Lewandowski

Relationship between Friction and Tactile Properties for Woven and Knitted Fabrics

The relationship between friction and the tactile properties of woven and knitted fabrics was investigated. Coefficients of friction for the fabrics were measured using two devices: a previously developed Textile Friction Analyzer and the Kawabata Evaluation System FB4. The tactile properties of the fabrics were evaluated by a panel, which assessed the roughness and the prickle of textile surfaces in two different blind subjective tests. Correlation between fabric friction and subjectively perceived touch properties was found for knitted, but not for woven fabrics. In order to find out if additional parameters could have influenced the obtained relationship, textile properties such as bending, compression, basis weight, hairiness and fabric thickness were investigated. Using principal component analysis, we found that the relevant properties in the relationship between friction and the touch properties of fabrics were bending, thickness and compressibility. On the other hand, the friction results showed a lack of commonality between the friction analyzer and the Kawabata surface tester, although there seemed to be a negative correlation between the two apparatus. This was attributed to the different testing conditions such as applied load, sliding speed, contact area and material surfaces and illustrated the dependence of fabric friction properties on testing variables

A Flexible Strain Sensor Based on a Conductive Polymer Composite for in situ Measurement of Parachute Canopy Deformation

A sensor based on a Conductive Polymer Composite (CPC), fully compatible with a textile substrate and its general properties, has been developed in our laboratory, and its electromechanical characterization is presented herein. In particular the effects of strain rate (from 10 to 1,000 mm/min) and of repeated elongation cycles on the sensor behaviour are investigated. The results show that strain rate seems to have little influence on sensor response. When submitted to repeated tensile cycles, the CPC sensor is able to detect accurately fabric deformations over each whole cycle, taking into account the mechanical behaviour of the textile substrate. Complementary information is given concerning the non-effect of aging on the global resistivity of the CPC sensor. Finally, our sensor was tested on a parachute canopy during a real drop test: the canopy fabric deformation during the critical inflation phase was successfully measured, and was found to be less than 9%.

Influence of fiber diameter, fiber combinations and solid volume fraction on air filtration properties in nonwovens:

In air filtration, nonwoven materials are known to be pertinent structures for fine filtration and moderate pressure drop. In order to develop a filter that combines good permeability and high efficiency, it is important to identify the relevant structural parameters of the nonwoven. The main criteria studied in this paper are fiber fineness, solid volume fraction and basis length (total length of fiber in unit area of nonwoven). The effect of combining different fiber diameters in order to reach the best compromise is also investigated. Our results show that the use of binary blends of different fiber diameters improves overall filtration behavior, in comparison to nonwoven filters with equivalent unimodal diameter distribution. A theoretical filtration model is used to predict filtration behavior for different structural characteristics and these predictions are compared to experimental results. However, this comparison demonstrates the limits of existing models in the case of fiber blends.

Study of the Influence of Fiber Diameter and Fiber Blending on Liquid Absorption Inside Nonwoven Structures

The purpose of this work was to investigate how nonwoven fabrics absorb and diffuse liquids and to define relevant diffusion parameters, with a special focus on the influence of fiber diameter on the diffusion process. The nonwoven structures studied were composed of polyester fibers of different diameters and were manufactured with a drylaid/needlepunching process. The liquid diffusion properties were evaluated with decane, a perfectly wetting liquid. Two methods based on vertical wicking (one direction) and absorption capacity measurements were used. The vertical wicking test results showed that finer fibers led to higher capillary absorption ability, but to the detriment of liquid absorption rate. Blending two fibers of different diameters improved the liquid retention behavior, while maintaining absorption rates that were equivalent to nonwovens with the coarser fibers. Finally, the different results obtained in the two experimental methods for the liquid filling ratio are discussed.

An evaluation of fiber orientation and organization in nonwoven fabrics by tensile, air permeability and compression measurements

Three indirect techniques—tensile, compression, and air permeability measurements—have been used to investigate the fiber network organization inside a highly porous nonwoven. They are standard material property measurements that require relatively simple equipment and are hence an interesting alternative to more costly direct analysis methods such as image analysis or X-ray tomography. The tensile measurement provides information on in-plane anisotropy of the nonwoven, through the use of an experimental parameter obtained from the tensile moduli measured in two perpendicular directions. The air permeability and compression analyses are based on existing models that describe the 2D or 3D isotropy. It is also possible to obtain two characteristic lengths that describe the fiber network: the hydrodynamic diameter and the mean distance between fiber junctions. Another important parameter is the fraction of fibers oriented in the thickness direction that could be determined from the permeability data. Our study shows that the observations and results from all three independent techniques are very well correlated for the range of nonwovens studied, and thus provide coherent description and insight of their internal structure. The nonwovens were found to exhibit in-plane anisotropy, while fitting 3D isotropic models in compression and permeability behavior.

Development and Characterization of 3D Nonwoven Composites

The aim of this paper is to present the results of a study showing the potential use of nonwoven textile structures as reinforcement in composite applications. Lightweight 3D porous composite materials have been developed from sandwich nonwovens obtained by combining several nonwoven monolayers manufactured with needlepunching and/or hydroentanglement consolidation treatments. The different structures - nonwovens and composites have been characterized, essentially with a quasi-static compression. Theoretical models have been applied to evaluate the fibre arrangement through the average fibre contact length or equivalent pore size inside the material. A difference in behaviour in compression has been observed for the different structures, and has been explained in terms of the different fibre arrangement inside the nonwoven structure which is related to the process.

Smart textiles in automotive interiors

In this chapter different smart textile structures suitable for use in car interiors are presented. One of the main interests of smart textile integration in car interiors is also related to the ‘customization’ trend. Designing very low weight car seats with heating fabric and achieving space saving and comfort thanks to a more breathable structure are now possible. However, only few applications can be found today involving smart textile structures comprising sensors, actuators, and computing and storage devices integrated into internal car elements. On the other side, car interiors contain a range of textile surfaces that may host textile-based sensors and actuators adapted to this specific space. They may be classified in function of the measured parameters and effects they are able to generate. This classification is given below: • Sensors: temperature, humidity, strain, UV radiation, acceleration, light intensity, etc.