Ramasamy Alagirusamy’s research while affiliated with Indian Institute of Technology Delhi and other places

Current cut protective gear is subject to several difficulties, such as the use of heavy fabric, complicated donning processes, lack of comfort and limited movement. When selecting the most comfortable cut protective fabric, it is important to consider the end users' specific needs. The aim of this study was to enhance the comprehension and optimisation of protective apparel for superior occupational safety and protection by exploring the intricate link between material composition, yarn structure and comfort parameters. Various combinations of filament twisted core sheath yarn consisting of stainless-steel/glass with high-performance polyethylene and polyester wraps were used to fabricate thermo-physiological comfortable cut protective workwear fabric. Twelve cut protective fabrics with the same areal density (200 g/m2) were prepared with 6-end satin weave using filament twisted core sheath yarn of five distinct linear densities (98.4 tex, 73.8 tex, 59.1 tex, 49.2 tex and 39.4 tex). These fabric samples were used to evaluate thermophysiological characteristics, including air permeability, dry and evaporative heat resistance, thermal conductivity, moisture permeability, wettability and moisture wicking according to the established standard. The cut protection of each sample was also measured according to EN 13997. The cut protection and thermo-physiological comfort attributes of cut-resistant clothing are greatly influenced by the proportion of core material (stainless-steel/glass) and yarn structural parameters (linear density and twist direction), which was observed by analysing the results. An increased core material percentage (stainless-steel/glass) contributes to increased fabric thickness and reduced bulk density, which influences the thermophysiological comfort attributes of the developed cut protective workwear fabric. Fabric made from a higher proportion of core material (stainless-steel/glass) with a lower bulk density exhibited an acceptable cut protection level and performed better in terms of thermo-physiological comfort attributes.

Firefighters in such serious environments (i.e., hazardous flames and radiant heat, high air temperatures, hot chemicals and liquids) must wear fire protective clothing during fire extinguishing and rescue operations. Many studies in the field of fire protective clothing have been conducted to evaluate the protective, mechanical and comfort performance of fire protective clothing. A comprehensive review of the literature has been undertaken to provide a better understanding of single-layer and multilayer fire protective clothing with protective, mechanical and comfort performance. Factors affecting the durability of protective clothing in the light of their expected retirement age and a number of significant standards for laboratory and manikin testing are discussed. The comfort of wearing clothing is another aspect that needs special consideration when designing a multilayered fire protective suit. A number of emerging technologies have been outlined to address the various challenges of the present day.

Thermal protective performance of protective clothing is greatly affected by structural parameters of fabric, air gap, and orientation of testing. This paper used Box-Behnken design experimental design to see the influence of pick density of shell (outer) layer, air gap, and orientation of test on thermal protective performance in terms of protection time. The testing was done at constant radiant heat flux. Thermal protective performance was measured in terms of second degree burn time using Stoll’s curve. The model showed F value of 72.98 and p-value 0.0001 which shows that model was significant. It was also found that there was significant effect of pick density, air gap, and orientation angle on thermal protective performance. There was positive effect of pick density and air gap but negative effect of orientation angle. This was also observed that effect of pick density was more when air gap increases. The study can help in development of thermal protective clothing for different parts of body.

High‐performance thermoplastic composites of polyketones [poly‐aryl‐ether‐ketone (PAEK), poly‐ether‐ether‐ketone (PEEK), poly‐ether‐ketone‐ketone (PEKK)] reinforced with continuous carbon fiber (CF) were consolidated using towpreg produced by multi‐scale aqueous dispersion coating technique. An intra‐matrix trend of composite strength and void fraction was studied to identify the composite with maximum strength free of voids for each polyketone matrix. The CF/PAEK composite with a flexural strength of ~2047 MPa and ILSS of ~99 MPa with a fiber volume fraction of ~67% had the maximum strength free of voids among CF/PAEK composite and all polyketone composites studied. The highest crystallinity (34.5%), and the highest amount of hydrogen bonding and bonds formed between CF, PI nanoparticle, and PAEK explained the origin of strength in CF/PAEK composite. The maximum strength among CF/PEEK and CF/PEKK composite free of voids had a flexural strength of ~1861 MPa, ~1981 MPa; ILSS of ~74 MPa, ~60 MPa; fiber volume fraction of ~61% and ~ 65%, respectively. The polyimide (PI) nanoparticles layer on CF formed the fiber matrix interface, supported hydrogen bonding in all polyketone composites, and formed bonds with CF and matrices of PAEK and PEEK establishing a synergistic effect. Highlights Intra‐matrix trend of strength and voids in polyketone composites studied. Void‐free, high‐performance, high fiber volume fraction composites developed. CF/PAEK composite had maximum strength among polyketone composites studied. PI nanoparticles formed bonds with CF and matrices of PAEK and PEEK. CF/PAEK composite strength originates from crystallinity, H bond, and bonding.

The study examined the fire protection performance of several woven products. Given that the comfort and fire protection properties of fire protective clothing (FPC) are opposite, it is important to consider the specific needs of firefighters when selecting the most suitable structure from various plain-woven derivatives, such as plain, basket, and ripstop. The yarn used was Nomex IIIA, which is a type of meta-aramid fibre. To achieve different thread densities, the pick density was adjusted while keeping the end density constant. The physical characteristics, thermal protective performance, thermal resistance, thermal conductivity, water vapour transmission rate and air permeability of all samples were assessed according to the appropriate standards. The goal was to identify the weave structure with the highest performance and the most optimal thread density. The basket weave structure was proposed as a fire protective clothing (FPC) having comfort qualities at a moderate level. Furthermore, increased density provided enhanced fire resistance, however, comfort must be sacrificed. Thus, to achieve a balance between fire protection and comfort, it was recommended to choose a thread density that is of an average level and the suggestion made by this research is to use the fabric as a basket weave design with an ends per inch of approximately 42, it is recommended to retain the pick density within the range of 46 with 44 tex Nomex IIIA yarn. The results of this study may be replicated in other designs using Nomex IIIA and comparable types of cloth and weave specifications.

In the present study, an attempt has been made to analyse the protection performance of fire-protective clothing. Various exposures to the same fabric in different configurations result in different protection performances. Box-Behnken experiment design was used to optimize the process parameters such as pick density (P), heat flux (Q), and air gap (D). Through surface methodology response, the relationship among the process parameters such as pick density (P), heat flux (Q), and air gap (D) was established. The experimental multi-parametric equation for calculating the radiant protection time (RT) and flame protection time (FT) was acquired. The fabric used was developed with 2/40 Ne Nomex IIIA yarns. The pick density (P) ranged from 40 to 64 picks per inch, heat flux (Q) ranged from 0.5 to 1.5 cal/cm2/sec, and air gap (D) ranged from 0 to 25 mm. To experimentally determine the level of protection, Stoll criteria were used. The experimental and predicted protection time values show a high correlation coefficient value (R2 = 0.985 for radiant and 0.978 for flame). The maximum improvement in protection was obtained at a high level of air gap (25 mm), low level of heat flux (0.5 cal/cm2/sec) and low level of pick density (40 picks per inch). Obtained results, calculations and equations will help researchers explore the empirical equation of the Box-Behnken model and other surface response curves. The values of protection time, in the specified range of the process parameters, by a single calculation could be possible to obtain.