Ningtao Mao

The Thermal Insulation Properties of Spacer Fabrics with a Mechanically Integrated Wool Fiber Surface

In relation to the engineering of compression resistant thermal insulation materials, an unconventional application of hydroentangling technology is introduced in which, lightweight, wool webs are mechanically attached to one side of preformed knitted spacer fabrics to partially occlude the underlying apertures. In contrast to conventional homogeneous fabrics, the resulting hydroentangled wool fiber web-spacer fabric constructs have markedly reduced thermal conductivity while there is little change in the overall fabric density; this is attributed to increased air entrapment within the cross-section of the spacer fabric due to the occlusion of the large apertures in the surface. Basic underlying theoretical principles are reviewed in relation to heat transfer in fibrous materials.

Anisotropic liquid absorption in homogeneous two-dimensional nonwoven structures

The anisotropy of liquid absorption is influenced by the fiber orientation distribution in the fabric plane. A unique theoretical analysis of planar fluid transport using D’Arcy’s law with two-dimensional directional permeability in nonwoven structures is presented which takes into account the fiber orientation distribution of the structure.

Directional Permeability in Homogeneous Nonwoven Structures Part II: Permeability in Idealised Structures

The application of a newly derived model of directional permeability, presented in Part I of this series of papers, is described for a range of specific fibre-orientation profiles. A consideration of the permeability results predicted by both the new model and existing theoretical and empirical models indicates that it is of practical use and is generally applicable to fibrous media of either low or high porosity.

Capillary pressure and liquid wicking in three-dimensional nonwoven materials

The capillary pressure and liquid wicking in fibrous nonwoven materials depend on the structural arrangement of fibers in three dimensions, which is influenced by the method and conditions used to manufacture the material. By adapting the hydraulic radius mechanism and drag force theory, a model is established for predicting the directional capillary pressure in three-dimensional nonwoven materials. As a case study, equations to predict the velocity of liquid wicking in a one-dimensional wicking strip test for nonwovens having a three-dimensional fiber orientation distribution are given based on the newly established capillary pressure model. These models and equations are based on measurable structural parameters including the fiber orientation distribution, fiber diameter, and fabric porosity.

Differences in the Tensile Properties and Failure Mechanism of PP/PE Core/Sheath Bicomponent and PP Spunbond Fabrics in Uniaxial Conditions

The tensile failure mechanism in thermally point-bonded bicomponent spunbonds is elucidated based on core/sheath PP/PE filaments. These fabrics exhibit high extension and low tensile strength. In contrast to 100% PP spunbonds, where there is limited bond deformation prior to failure of the fabric, the bond points in PP/PE bicomponent spunbonds undergo large deformations during uniaxial extension before fabric breakage occurs. Failure occurs mainly within the bond points rather than around their perimeter.

Modeling permeability in homogeneous three-dimensional nonwoven fabrics

A simplified three-dimensional structural model for a series of nonwoven fabrics is presented. The corresponding directional permeabilities of the fabrics are calculated based on the measured two-dimensional fiber orientation distribution. The influences of fiber diameter, fabric porosity, and fiber orientation distribution on the directional permeabili ties are considered.

Human wetness perception of fabrics under dynamic skin contact

This experiment studied textile (surface texture, thickness) and non-textile (local skin temperature changes, stickiness sensation and fabric-to-skin pressure) parameters affecting skin wetness perception under dynamic interactions. Changes in fabric texture sensation between WET and DRY states and their effect on pleasantness were also studied. The surface texture of eight fabric samples, selected for their different structures, was determined from surface roughness measurements using the Kawabata Evaluation System. Sixteen participants assessed fabric wetness perception, at high pressure and low pressure conditions, stickiness, texture and pleasantness sensation on the ventral forearm. Differences in wetness perception (p < 0.05) were not determined by texture properties and/or texture sensation. Stickiness sensation and local skin temperature drop were determined as predictors of wetness perception (r2 = 0.89), and although thickness did not correlate with wetness perception directly, when combined with stickiness sensation it provided a similar predictive power (r2 = 0.86). Greater (p < 0.05) wetness perception responses at high pressure were observed compared with low pressure. Texture sensation affected pleasantness in DRY (r2 = 0.89) and WET (r2 = 0.93). In WET, pleasantness was significantly reduced (p < 0.05) compared to DRY, likely due to the concomitant increase in texture sensation (p < 0.05). In summary, under dynamic conditions, changes in stickiness sensation and wetness perception could not be attributed to fabric texture properties (i.e. surface roughness) measured by the Kawabata Evaluation System. In dynamic conditions thickness or skin temperature drop can predict fabric wetness perception only when including stickiness sensation data.

High performance textiles for protective clothing

Abstract: In this chapter, the characteristic physical properties of high performance textile materials are reviewed, and examples of their applications in the engineering design of protective clothing are given, together with a brief introduction to the legal requirements for protective clothing. As a case study, the functions of high performance textile materials used in cut resistant products, firefighters’ clothing, chemical protective clothing and materials for achieving thermophysiological comfort in protective clothing are discussed.

Permeability in Engineered Non-woven Fabrics Having Patterned Structure

The patterned non-woven fabric structure is a typical non-homogeneous non-woven fabric and is frequently used as a hygienic medical absorbent material to control fluid transport for directional delivery. In this paper, the characteristics of the structural variation in both strip and point patterned non-woven fabrics are examined, and the relationship between the global permeabilities in both the transverse and in-plane directions in the patterned non-woven fabrics and the local fabric structural parameters (e.g. fiber diameter, fiber orientation distribution, fabric porosity, and local pattern dimensions) is established.

Unsteady-state Liquid Transport in Engineered Nonwoven Fabrics having Patterned Structure

The initial stage of liquid absorption in unsaturated nonwoven fabrics (e.g. dry wipes, absorbent materials and hygiene products) is an unsteady-state fluid flow. For the purpose of the engineering design of these nonwoven products, there is a need to predict the unsteady-state fluid flow in both homogeneous anisotropic nonwoven structures and heterogeneous patterned nonwoven fabrics having a dual-scale porosity structure. In this paper, the unsteady-state liquid wicking in homogeneous anisotropic nonwoven fabric structure has been modeled, and the relationship between unsteady-state liquid absorption in patterned nonwoven fabrics and its structural parameters has been established based on the fabric structural parameters.