Arun Vijayan

Bismuth oxide-coated fabrics for X-ray shielding

Lead aprons are widely used in medical imaging to protect radiographers and patients from harmful radiation. However, lead is not a desirable material for use in wearable radiation protection due to its heavy weight, inflexibility, poor durability, and toxicity. In this study, we explored the suitability of bismuth oxide (Bi2O3) coating for textiles as an alternative to lead. The intention was to demonstrate the concept and technology that will achieve a lead-equivalent lightweight X-ray protective textile material with improved wearability. The primary objective was to evaluate the X-ray shielding efficiency of two textile materials coated with Bi2O3. To do so, X-ray exposures were made at the system setting of 80 kVp, 12 mAs, and 80 SID (the distance from the X-ray beam source to the specimen). It is evident from this study that Bi2O3 in a suitable resin matrix can be coated on fabrics and is an effective method to produce flexible, wearable, and lead-free aprons. Coated polyester fabrics with over 50% Bi2O3 showed enhanced shielding ability for transmitted X-rays. This research has shown that microparticle size Bi2O3 can be effective for X-ray attenuation.

Chemical and water protective surface on cotton fabric by pad-knife-pad coating of WPU-PDMS-TMS

Surface functionalization of textiles is crucial in developing protective clothing that protects wearers from potential hazards of liquid, chemical and biological contamination. This study aims to explore chemical and water protective surface on cotton fabric by pad-knife-pad coating of waterborne polyurethane (WPU), polydimethylsiloxane (PDMS) and trimethylated silica (TMS). The chemical structure of the coated cotton fabrics was characterized by attenuated total reflectance Fourier transform infrared spectroscopy. Surface wettability and liquid protective properties of the coated cotton fabrics were analyzed by water contact angle, water repellency, hydrostatic pressure, and oil and aqueous liquid repellency. It was revealed that WPU and PDMS-TMS formed copolymerization reactions, resulting in ultrahydrophobic, oil repellent and mechanically strong membrane on the surface of cotton fabric. It has been found that the coating of WPU-PDMS-TMS makes cotton fabric highly resistant to water, oil and aqueous liquids. This surface functionalization technology can be further applied in developing protective clothing with chemical and water resistant and self-cleaning properties.

The impact of super-absorbent materials on the thermo-physiological properties of textiles

The use of appropriate protective clothing systems in high-risk environments is absolutely essential. Such protective clothing may not provide the desired wearer comfort due to the complexities associated with the system. These constraints are largely due to the multiple layers involved in the protective ensemble. Firefighters’ protective clothing systems, in particular, have limited or no water vapor permeability. This prevents evaporative heat loss and leads to thermal strain and sweat accumulation. This accumulated sweat on the skin and on the internal layer close to the body causes considerable discomfort to the user due to the sensation of wetness. Extensive research has been done to improve the comfort properties of such protective clothing. This research adds yet another dimension where a new inner-layer construction has been developed with high liquid and vapor-absorption capacity that could assist in keeping the moisture and vapor away from the skin and, in addition, retain a dry microclimate close to the skin. The developed materials were tested for their biophysical properties that included tests such as thermal and water vapor resistance, air permeability and moisture management properties. Experimental results in this study indicated that super-absorbent materials, when incorporated into a woven textile material, showed enhanced wearer comfort. It was observed that these super-absorbent materials have the capability to quickly wick the moisture away from the body and, in doing so, have the tendency to keep the skin dry.

Effect of repeated laundering and Dry-cleaning on the thermo-physiological comfort properties of aramid fabrics

This research investigated the effect of repeated laundering and dry-cleaning on the physical and thermophysiological comfort properties such as air permeability, water vapour resistance and thermal resistance of fabrics made of meta-aramid (Nomex®) fibre. Two different types of fabric were selected for the study and subjected to repeated laundering and dry-cleaning (1, 5 and 10 cycles), which is commercially used for the care and maintenance of these fabrics. The fabric thickness, areal density, thermal resistance and water vapour resistance values increased with the number of laundering cycles, whereas the air permeability decreased due to the fabric shrinkage and swelling. On the other hand, the thickness and air permeability of the dry-cleaned fabric samples increased with the number of cycles; while the water vapour resistance and thermal resistance decreased. The scanning electron microscopy images showed the structural changes as indicated by the longitudinal fibrillation in the fabrics subjected to laundering or dry-cleaning.

Evaluation of thermal, moisture management and sensorial comfort properties of superabsorbent polyacrylate fabrics for the next-to-skin layer in firefighters’ protective clothing:

This research investigated the transport properties (such as thermal resistance, water vapor resistance and air permeability), moisture management capacity and sensorial properties of some knitted structures of superabsorbent polyacrylate in order to explore their potential as next-to-skin layers in firefighters’ protective clothing in Australia. Test results using these fabrics were compared with the currently used next-to-skin woven fabric. Three different knitted structures (i.e. jersey, rib and interlock) were selected for the study in addition to the current woven fabric in use by Australian firefighters. It was observed that the knitted fabric samples of superabsorbent polyacrylate retained higher amounts of water compared to the fabric sample currently used in the firefighters’ clothing. However, the woven fabric sample dried at a faster rate. Hence, a blended fabric of polyacrylate with the current Nomex® fabric can help in higher sweat absorption and faster drying. The thermal and water vapor resistance of jersey fabric was the lowest, which may better facilitate the transfer of metabolic heat and vapor to the environment, resulting in better thermal comfort. Furthermore, all the fabric samples showed a low coefficient of friction (∼0.2), which indicated less tactile discomfort if the fabrics are worn as the next-to-skin layer in the firefighters’ clothing. The overall moisture management properties of the fabric samples were rated as fair to good. The findings of this research suggest that the superabsorbent material has the potential to be used in place of the existing next-to-skin layer of firefighters’ protective clothing, with better sweat absorption capacity and thermal comfort.

Degradation of Fluorescent High-Visibility Colors Used in Safety Garments for the Australian Railway Industry

INTRODUCTION This study investigated the compliance of four fluorescent orange high-visibility garment substrates that are predominantly used in the Australian railway industry. While Special Purpose Orange (SPO), a shade of the Fluorescent orange (Fl-orange) is recommended by most Australian states as the high-visibility background color of a safety garment, there appear to be variations in the background color of clothing used by line-workers and rail contractors. The color of the garment was assessed for compliance with the Australian Standard AS/NZS 1906.2.2010 for high-visibility materials for safety garments. The results were also compared with ANSI Z535.2011 and BS EN ISO 20471.2013 Standards. METHOD Photometric and colorimetric assessments of the background color of the garment substrates were performed using a spectrophotometer and were evaluated for compliance with the Standards after washing and exposure to UV. RESULTS The spectrophotometry measurements showed that Fl-orange background color for all samples except one complied with the AS/NZS 1906.2 Standard for daytime high-visibility garments after 20 washes but failed to comply after exposure to UV. It was also found that the chromaticity coordinates of the corners of the Fl-orange color space, specified in the AS/NZS 1906.4.2010 Standard are much wider and yellower when compared with the ANSI Z535.1.2011 and BS EN ISO 20471.2013 Standards. The sample that failed to comply with the Australian and American Standards however complied with the ISO Standard. PRACTICAL APPLICATIONS Irrespective of the Standard used, the research has shown the degrading effect of washing and light exposure and raises the questions as to how regularly, and under what conditions high-visibility garments need to be replaced. These findings will provide information for safety garment manufacturers about the characteristics and performance of high-visibility safety garments which make them conspicuous during daytime use. This research recommends that colors for railway workers should be chosen based on the conspicuity, commercial viability, reproducibility and durability rather than simply adopting standards from other industry domains or other countries.

Evaluation of X-ray radiation shielding performance of barium sulphate-coated fabrics

The X-ray in the field of medical imaging is an important diagnostic tool, but it has been identified that there are potential radiation risks associated with the X-ray radiation scans. These risks have traditionally been guarded against using lead based shields. Lead has excellent radiation shielding properties, but it is also heavy and a potential health and environmental hazard due to its toxicity. Thus, there have been studies seeking to find an alternative that is as effective and yet counters the other drawbacks. In this paper, preliminary studies were conducted to assess the shielding effect of barium sulphate (BaSO4) and bismuth oxide (Bi2O3) on the coated fabric samples. X-ray transmission resulting from standard lead coated samples, uncoated fabric, BaSO4, and BaSO4/Bi2O3 coated fabrics was evaluated via measuring the penetration of primary radiation. Different properties such as mass per unit area, material thickness, and surface morphology were examined. All samples were irradiated by X-ray at 80 kVp to measure the amount of transmissions. The X-ray transmission level associated with BaSO4 ranged from 84.5 % to 70.5 %. However, this level was elevated to 55.6 % when BaSO4/Bi2O3 mixture was applied on the fabric. The theoretical attenuation coefficient values associated with different coating mixtures comprising different weight proportions of BaSO4, Bi2O3, and PVC were determined between 0 MeV and 105 MeV using XCOM code. The XCOM results implied that the X-ray attenuation coefficient among all prepared coatings should be the mixture comprising 13.3 wt% Bi2O3/20 wt% BaSO4/66.7 wt% PVC, which was in agreement with the experimental results obtained from X-ray transmission measurements.