Subhash Anand

Novel “3-D spacer” all fibre piezoelectric textiles for energy harvesting applications

The piezoelectric effect in poly(vinylidene fluoride), PVDF, was discovered over four decades ago and since then, significant work has been carried out aiming at the production of high β-phase fibres and their integration into fabric structures for energy harvesting. However, little work has been done in the area of production of “true piezoelectric fabric structures” based on flexible polymeric materials such as PVDF. In this work, we demonstrate “3D spacer” technology based all-fibre piezoelectric fabrics as power generators and energy harvesters. The knitted single-structure piezoelectric generator consists of high β-phase (∼80%) piezoelectric PVDF monofilaments as the spacer yarn interconnected between silver (Ag) coated polyamide multifilament yarn layers acting as the top and bottom electrodes. The novel and unique textile structure provides an output power density in the range of 1.10–5.10 μW cm−2 at applied impact pressures in the range of 0.02–0.10 MPa, thus providing significantly higher power outputs and efficiencies over the existing 2D woven and nonwoven piezoelectric structures. The high energy efficiency, mechanical durability and comfort of the soft, flexible and all-fibre based power generator are highly attractive for a variety of potential applications such as wearable electronic systems and energy harvesters charged from the ambient environment or by human movement.

A study of the structure and properties of novel fabrics for knee braces

The knee is the most used joint in the human body and is also most prone to injuries. Knee braces are medical devices used in the treatment of some form of injuries providing compression and warmth to the joint thus promoting healing. They can also be used for protection in several contact sports. At the moment there are no regulations governing the textile materials used in braces. The authors believe that knitted spacer fabrics have the desirable mechanical and comfort properties which could make these materials suitable for some medical applications. Commercially available knee braces have been tested and analyzed for their mechanical as well as thermophysiological properties. A range of novel spacer fabrics have been designed, developed, and characterized for comparison with commercial products. It has been found that knitted spacers can be engineered in terms of yarn type and structure used in each of the three layers in order to match and even outperform the properties exhibited by commercially available products, such as neoprene and other knitted fabrics, including composite materials. The test results obtained for a range of existing and novel products studied in this work have been explained in terms of their raw material, structure, and finishing treatments applied to them.

Effects of Various Home Laundering Practices on the Dimensional Stability, Wrinkling, and Other Properties of Plain Woven Cotton Fabrics Part II: Effect of Rinse Cycle Softener and Drying Method and of Tumble Sheet Softener and Tumble Drying Time

For a systematic study of the effect of laundering on plain woven cotton fabrics, specimens of poplin and sheeting fabrics (with and without a DMDHEU wrinkle resistant finish) are laundered under regimes designed to evaluate the effect of five common home laundering variables: use of detergent, rinse cycle softener, or tumble sheet softener. different drying methods, and different tumble drying times. The experimental method ology and the effect of using detergent were reported in Part I of this series. To reduce the cost and time involved in this and future investigations, the reproducibility of results from repeated but otherwise identical wash loads was evaluated and reported in Part I. Length and width shrinkage, skewness, wrinkling, mass of whole specimen, area density, and warp and weft yarn diameters were determined in Part I using standard test methods. Suitable statistical techniques and analysis are used throughout the study. The effects of fabric structure and an anti-wrinkle finish on the dependent variables are also studied.

Effects of Various Home Laundering Practices on the Dimensional Stability Wrinkling, and Other Properties of Plain Woven Cotton Fabrics Part I: Experimental Overview, Reproducibility of Results, and Effect of Detergent

As part of an ongoing research program on the effects of laundering on plain woven cotton fabrics, specimens of poplin and sheeting fabrics with and without a DMDHEU wrinkle resistant finish are laundered under regimes designed to evaluate the effect of five common home laundering variables: use of detergent, rinse cycle softener, or tumble sheet softener, different drying methods, and different tumble drying times. To reduce the cost and time involved in this and future investigations, the reproducibility of results from repeated but otherwise identical wash loads is also evaluated. Length and width shrinkage, skewness, wrinkling, mass of whole specimen, area density, and warp and weft yarn diameters are determined using the appropriate standard test methods. The effects of fabric structure and application of an anti-wrinkle finish on the dependent variables are also studied.

Geotextiles: production, properties and performance

The monograph critically reviews most commonly used geotextile structures, their properties and performance characteristics. In general, both natural and synthetic fibres are used for the production of geotextiles, and the advantages and disadvantages of each type of fibre are discussed for various applications of geotextiles. The important functions of geotextiles, i.e. filtration, drainage, separation and reinforcement have been identified and have been related to several properties and major applications of geotextiles. Various geotextile properties, namely mechanical, hydraulic and chemical and their test methods have been critically discussed. A process–structure–property relationship for most commonly used geotextiles is also analysed. Furthermore, the design of a geotextile is of paramount importance for any civil engineering application. Thus, the design criteria for various functions of geotextiles have been addressed. Subsequently, the durability characteristics of geotextile have been introduced for analysing the performance over its lifetime.

Optimization of Parameters for the Production of Needlepunched Nonwoven Geotextiles

Needlepunched nonwoven geotextiles are widely used for various civil engineering applications. These applications are required to perform more than one function, i.e., filtration, separation, protection, drainage, and reinforcement. Reinforcement is a complex phenomenon and strongly depends upon the fabrics dimensional and mechanical properties in addition to the soil—geotextile interaction. In this study, the effect of process parameters including web area density, punch density, and depth of needle penetration has been investigated on dimensional (area density and thickness) and mechanical (puncture resistance and tensile strengths in the machine and cross-machine directions) properties of needlepunched nonwoven geotextiles. These process parameters are then empirically related with the fabric properties using multiple regression technique. The anisotropic characteristics of needlepunched nonwoven geotextiles tensile properties have also been discussed.

Development of Advanced Personal Protective Equipment Fabrics for Protection Against Slashes and Pathogenic Bacteria Part 1: Development and Evaluation of Slash-resistant Garments

Knife is the most commonly used single weapon in the UK, being 32% of the weapons used in violent incidents. Studies reveal that the majority (63.3%) of the knife-inflicted wounds were slash-type and could be disfiguring or life threatening if the blood vessels are ruptured. The stab-resistant armors currently available do not protect the arms, neck, and face as they are very rigid to be worn comfortably and are expensive and heavy for everyday use by the civilian population. The main objectives of this research program are to (a) develop and characterize a novel cut-resistant and slashproof material that is lightweight, comfortable, and efficient and (b) integrate barrier properties in such garments that would incorporate suitable antimicrobial and other suitable chemicals to provide protection against a range of microorganisms. During this research program, various composite yarns were thoroughly investigated, at different proportions, to determine the most appropriate yarn for the slashproof material. The slashproof fabric structures were developed by using knitting technology as it offers significant advantages in terms of cost, design flexibility, and versatility. The fabrics were characterized by using Home Office Scientific Development Branch (HOSDB) Slash Resistance Standard for UK Police (2006), Publication No. 48/05. The results indicate that the developed fabric meets the criteria required by the HOSDB. The article discusses the results obtained during the development of the novel slashproof material for the police, armed forces, children, and the public, that is lightweight, comfortable, and efficient, and can be utilized for long periods.

Effect of Tumble-drying on Selected Properties of Knitted and Woven Cotton Fabrics: Part II: Effect of Moisture Content, Temperature Setting, and Time in Dryer on Cotton Fabrics

Specimens of a plain-woven cotton fabric and a plain single-jersey weft-knitted cotton fabric were washed and then tumble-dried for predetermined periods of time under three different temperature settings. Length and width shrinkage, wrinkling, mass of the whole specimen, and warp and weft yarn diameters were determined by using the appropriate standard test methods. The interdependence of moisture content, temperature setting, and time in the tumble dryer was reported in Part I of this series. In Part II, their effects on the dimensional stability and appearance of both knitted and woven cotton fabrics are reported. It is demonstrated that temperature setting in tbe tumble dryer bad no effect on shrinkage. The increased exposure to agitation that occurred in tumble-drying under a low temperature setting had no effect on shrinkage. Low temperature setting and prolonged exposure to agitation were, however, slightly beneficial to the appearance of the plain-woven cotton fabric used.

Effects of Laundering on the Sensory and Mechanical Properties of 1 X 1 Rib Knitwear Fabrics Part I: Experimental Procedures and Fabric Dimensional Properties

Acrylic, cotton, and wool 1 × 1 rib knitwear fabrics have been subjected to up to 50 laundering cycles using a variety of washing and drying conditions. The dimensional, mechanical, and tactile properties of new and washed fabrics are determined and evaluated using standard test procedures. In Part I, we establish the techniques for predicting the final, fully relaxed dimensions of knitted fabrics. We determine fully relaxed k-constant values and the influence of fiber type and washing and drying methods on these values. In Part II, we will discuss the changes in mechanical and tactile properties that occur in these fabrics with repeated washing.

Effect of Tumble-drying on Selected Properties of Knitted and Woven Cotton Fabrics: Part I: Experimental Overview and the Relationship between Temperature Setting, Time in the Dryer and Moisture Content

Specimens of a plain-woven cotton fabric and a plain single-jersey weft-knitted fabric were washed and then tumble-dried for predetermined periods of time under three different temperature settings. Length and width shrinkage, wrinkling, mass of whole specimen, and warp and weft yarn diameters were determined by using the appropriate standard test methods. Tbe interdependence of moisture content, temperature setting and time in tbe tumble dryer is reported in Part I of tis series of papers. Their effects on the dimensional stability and appearance of both knitted and woven cotton fabrics are reported in Part II of tis series. It is demonstrated that temperature setting in the tumble dryer had no effect on shrinkage. The increased exposure to agitation that occurred in tumble-drying under a low temperature setting had no effect on shrinkage. Low temperature setting and prolonged exposure to agitation were, however, slightly beneficial to tbe appearance of tbe plain-woven cotton fabric used.