Reducing the physiological burden of individual protective clothing with nanocellulose

1. Introduction
The current technology used in individual protective equipment (IPE) apparel has provided a high level of protection against CBR warfare agents for military personnel. However, the physiological burden of wearing such clothing can be high. One major challenge is the removal of body heat, which could be facilitated by the use of air-permeable fabrics as these allow water vapour derived from sweat to escape the microclimate of the suit. However, if the air-permeability is too high the levels of protection can fall significantly. Hence, there is an interest in promoting the permeation of water vapour out of the suits without impeding the level of protection. Inspired by the hydrophilic nature of nanocellulose and their recent applications in enhancing nonwovens fibres and filtrations, it is thus proposed to incorporate nanocellulose in developing a light and multifunctional IPE costume with reduced physiological burden.
Project aims:
Microbially-synthesised nanocellulose, e.g. bacterial cellulose (BC), would be employed in this particular project to produce a nanocellulose-enhanced IPE garment with resulting performance improvements over the state-of-the-art. The key objectives are:
1. To develop a cheap and simple manufacturing process BC-enhanced IPE garments with high moisture permeability and high size-exclusion efficiency comparable to the state-of-the-art;
2. To examine and optimise the properties of BC for liquid control, increasing the repellence of the IPE garments;
3. To design and optimise the multi-layer configuration of IPE garment incorporating BC to maximised protection efficiency.
2. Research methodology
2.1. Modification of textile fabric in the exterior garment of IPE with BC
It is proposed to improve the filtration efficiency of the IPE clothing by coating the yarns of the exterior garment layer with BC. The natural affinity of BC to textile fibres would allow BC to attach either at a single textile fibre yarn level or to bridge across multiple yarns. It is hypothesized that BC nonwoven would form a barrier within the fabric structure so as to reduce, to filter or to eliminate the passage of organic molecules or micro-particles. Slurry dipping method, in which fabrics will be dipped into a BC suspension and dried, will be employed to produce BC-coated yarns. Both the dipping time and the consistency of BC-in-water suspension will be varied to investigate and quantify the areal density of the resultant BC coating.
These BC coated fabrics would be characterised for their air permeability with Gurley densometer and filtration efficiency with model micro-particulates and well-defined particle diameter. Scanning electron microscopy might also be conducted to study the BC-textile yarn interface and other properties such as particulate filtration and contact angles.
2.2. Tailoring and enhancing the chemisorption capability of IPE garment with BC
IPE garments often consist of activated carbon loaded inner lining to remove potentially hazardous vapours through adsorption. However, it is challenging to functionalise the surface of this activated carbon layer to tailor the adsorption of specific hazardous organic molecule. On the contrary, BC possesses a broad chemical modification capacity and has thus exhibited opportunities to design bespoke surface properties for specific organic molecules adsorption.
For instance, it is proposed to oxidise BC with (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl (TEMPO) in order to introduce carboxylic groups onto the BC surface. TEMPO-oxidised BC has shown to be hydrophilic and would therefore absorb significant amount of moisture and further maximise body heat removal.