Subhash Anand

Partially and fully biodegradable natural fibre – reinforced composites have been prepared using a novel patented woven-nonwoven technology. Natural fibres included jute and sisal, whereas the matrices were of synthetic polymers derived from petroleum (polypropylene (PP)) or natural (polylactic acid (PLA)) resources. The physical, mechanical and flammability properties of these partially and fully biodegradable composites have been studied and compared with those of similarly produced glass-fibre reinforced PP and PLA composites with a view to enabling their use in automotive applications. Mechanical test results showed that the tensile and flexural moduli of the PLA composites were higher than respective PP composites. In comparison, sisal composites have higher tensile and flexural moduli than jute composites. The fire performance of the composites studied by cone calorimetry showed that while natural fibre reinforcement had no effect on time-toignition, peak heat release was significantly reduced. PLA composites had lower burning propensity compared to respective PP composites.

The increasing need of on-demand power for enabling portable low-power devices and sensors has necessitated work in novel energy harvesting materials and devices. In a recent work, we demonstrated the production and suitability of three-dimensional (3-D) spacer all fibre piezoelectric textiles for converting mechanical energy into electrical energy for wearable and technical applications. The current work investigates the textile performance properties of these 3-D piezoelectric fabrics including porosity, air permeability, water vapour transmission and bursting strength. Furthermore, as these textiles are intended for wearable applications, we have assessed their wear abrasion and consequently provide surface resistance measurements which can affect the lifetime and efficiency of charge collection in the piezoelectric textile structures. The results show that the novel smart fabric with a measured porosity of 68% had good air (1855 l/m2/s) and water vapour permeability (1.34 g/m2/day) values, good wear abrasion resistance over 60,000 rotations applied by a load of 12 kPa and bursting strength higher than 2400 kPa. Moreover, the antibacterial activity of 3-D piezoelectric fabrics revealed that owing to the use of Ag/PA66 yarns, the textiles exhibit excellent antibacterial activity against not only Gram-negative bacteria E. coli but they are also capable of killing antibiotic methicillin-resistant bacteria S. aureus.

Polyurethane (PU) foam is one of the most common materials used in the development of pressure relieving cushions. However, it suffers from reduced efficiency in terms of thermophysiological comfort, cost, recycling and importantly, creating a suitable environment for the prevention of pressure ulcers. The paper presents research carried out at the University of Bolton, in the development of pressure relieving cushion applications using three-dimensional (3D) warp-knitted spacer fabrics. This research includes the development of a novel technique for measuring pressure distribution while under simulated loading conditions. Using this system, novel and smart 3D knitted spacer cushions were developed, with the following features: (1) a shaped/contoured surface was able to redistribute high pressure points normally located in vulnerable areas of an immobile and seated person. (2) Peak pressures were reduced and distributed evenly over a much larger area of the cushion than PU foam. (3) They are well-ventilated, comfortable, washable and non-flammable and can be easily recycled.

This paper discusses that three-dimensional (3D) warp knitted spacer structures offer significant attributes that create sustainable production advantages in dry exhaust systems for the automotive paint industry. The advantages that are offered include improved airflow and the potential to combine to a composite solution with a high paint holding capacity; this concept of filtration also offers the possibility of a durable filter capable of industrial cleaning and reuse numerous times. The paper describes the innovation of these 3D warp knitted spacer filters from theoretical and traditional filtration aspects, followed by an empirical characterization that justifies commercial trials within the industry.

The paper focuses on the development of novel absorbent nonwoven structures by using natural biodegradable carboxymethylcellulose (CMC), alginate and polylactic acid (PLA) fibres. These fibres have been blended and reinforced with synthetic hollow polyester (HPES), polypropylene (PP) and hollow viscose (HV) fibres. The main aim was to enhance the wicking properties of the structures for minimising the pooling of exudate and maceration. It is also aimed to enhance the integrity of structures to minimise the contamination of wounds due to loose fibres. The incorporation of PLA into wound dressings has been attempted for the first time and their functional properties have been studied. The single-fibre, blended and hybrid fabrics have been engineered. The results demonstrate that HPES reinforcement has a critical importance for CMC fabric in terms of wicking properties, tensile properties and air permeability. It has also been demonstrated that the contribution of PLA in the wound dressings is to enhance the properties such as absorbency, wicking, flexural rigidity and air permeability.

The paper determines that the cause of retardation of innovation for industrial filtration applications is commercial supposition rather than technical performance. The paper describes a multi-dimensional framework for characterizing the required filtration attributes for attaining a more sustainable filter for bespoke industrial applications. This framework appreciates the fact that bespoke applications have complex environments as such a subjective approach is taken and the results are indexed to that used commercially in the application. Paint exhaust filtration has been used as the papers' framework example and laboratory characterization of this bespoke filtration is undertaken revealing the multiple key areas of focus. This multi-dimensional approach demonstrates it is possible to utilize subjective visual characterization followed by quantitative methods as an effective facilitator of sustainable filtration re-engineering.

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.

In this study, two common nonwoven fibrous dressings, based on carboxymethylcellulose and alginate, and their silver-treated forms were evaluated in order to compare their performance characteristics including fluid handling capacity, the mechanical properties, and the thermal behavior. The effect of immersing the dressings in the two fluids (solution A and distilled water) on pH was also studied. The results show some clear differences between the untreated and silver-treated dressings, for example the fluid handling and the swelling values of the dressings were reduced due to silver treatment. More considerably, changes were observed in the tensile properties which were decreased when these dressing were treated with the silver. There was no considerable effect on the thermal characteristics of the dressings upon the silver treatment. Statistically significant differences were observed in the pH over time for all tested specimens and also for both test fluids.

The design, manufacturing and characterization of warp knit textile structures with enhanced drapeability and energy absorption is reported in this paper. Four textile structures were produced, all based on a triangular or double arrowhead structure, which is known to lead to a negative Poisson's ratio ?. Mechanical testing has confirmed that textile structures can be produced which are auxetic at +/- 45 degrees to the warp direction, with ? of up to -0.22?+/-?0.03.