Abu Shaid

The thermal protection and comfort properties of aerogel and PCM-coated fabric for firefighter garment

The study evaluates the simultaneous use of aerogel and phase change material (PCM) on the face cloth of thermal liner in firefighter’s protective garment. Aerogel is commonly used to resist incoming heat flux in the field of high heat protection and to prevent the loss of body heat in the cold environment clothing. In high heat protection clothing, aerogel not only resists the incoming heat fluxes but also blocks the outbound body heat. As a result the wearer suffers from internal increase of body temperature. Previous studies identified the potential use of aerogel in firefighter’s protective clothing. However there was no clear approach to resolve the problem associated with body heat release. Current study focuses on the problem by applying PCM along with aerogel on fabric. The ambient-side of a thermal liner face cloth was coated with silica aerogel particles; meanwhile, the next to skin side was coated with PCM/aerogel composite powder. The new thermal liner revealed superior thermal protection and comfort. It extended the time to reach pain threshold and increased the pain alarm time. The Fourier transform infrared analysis of the aerogel/PCM composite powder showed the presence of PCM in nanoporous aerogel particles while the differential scanning calorimeter quantified the heat absorbing capacity of the new composite powder. Scanning electron microscope, air permeability tester, and jPOR macro of ImageJ software were used for the surface characteristics and porosity analysis of coated liner. The thermal stability of the composite powder was investigated through an infrared thermal camera. No dripping or form deterioration was observed when the composite powder was heated over a temperature three times above the melting temperature of the pure PCM.

Investigation on Dyeing Performance of Basic and Reactive Dyes Concerning Jute Fiber Dyeing

ABSTRACT This paper includes the investigation on the dyeing performance of reactive and basic dyestuff regarding jute fiber and discusses their benefits and shortcomings. Plain woven jute fabric samples of 261 GSM were dyed with 0.5%, 1.0%, and 4.0% shade of basic and reactive dyes. Then the dyeing performance of both dyestuffs was analyzed. It has been found that exhaustion of basic dye is considerably greater than reactive dye, while this exhaustion decreases for basic dye and increases for reactive dye with the increment of respective shade percentages. This phenomenon has also been verified through the absorption curve, i.e. K/S value of fabric dyed with both dyestuffs in three different shade percentages. Again strong covalent bond is formed during the fixation of reactive dye with the cellulose of jute fiber, and at the same time no strong bond was created in case of basic dye. Finally the color fastness properties have been assessed through rubbing and washing. Both the dye classes have shown nearly similar ratings in case of dry rubbing. However, in case of wet rubbing and wash fastness to color change and color staining; the samples dyed with reactive dyes showed superior fastness ratings over the basic dyed samples.

Decolorization of textile wastewater by gamma irradiation and its reuse in dyeing process

AbstractThis paper describes the scope of employing high-energy gamma irradiation for textile wastewater treatment and the possibility of using the treated wastewater in the dyeing of knitted cotton fabric. The treatment was carried out in Cobalt-60 gamma radiation source at different irradiation doses (3, 5, 8, and 12 kGy). Then, the irradiated wastewater was used for dyeing of cotton fabric with reactive dye. The performance of the fabric dyed with treated wastewater was compared to that of the fabric dyed with freshwater. Hence, the dyeing performance was evaluated by comparing the depth of shades of both types of dyed fabrics from the analysis of absorption spectrum (K/S value vs. wavelength). The absorption curves of irradiated wastewater dyed fabric in light, medium, and dark shade of three different colors have shown close match to their corresponding freshwater dyed fabric. Variation of shade between the dyed fabrics, representing by ∆E values, were also found within the maximum acceptable limit a...

Aerogel nonwoven as reinforcement and batting material for firefighter’s protective clothing: a comparative study

AbstractsAerogel, the most insulated solid known to modern science, is gradually expanding its field of application from space shuttle to normal clothing. So far, apparel use of aerogel nonwoven has been successfully commercialized in case of cold weather clothing. Use of aerogel in high heat protective clothing is much complex as it requires to balance comfort with protection. This paper studied the protective performance of aerogel nonwoven in a high heat protective apparel, firefighter’s protective clothing (FPC). An investigation was carried out to justify its use as reinforcement material and/or batting in thermal liner or moisture barrier of FPC. Impressive results were observed in case of reducing the risk of burn injury, increasing comfort and enhancing protection. It was observed that aerogel nonwoven can provide eight times more thermal resistance than existing commercial reinforcement material and existing thermal batting material. When the aerogel nonwoven layer was used as thermal liner, it offered five times more resistance to heat than existing thermal liner and three times more resistance than combined performance of existing thermal liner and moisture barrier. The possible burn injury under 49 N compressive load was predicted on a 200 °C heated surface. It was found that the temperature behind the commercial reinforcement material quickly raised above 70 °C within 30 s of contact, while it took more than 4 min to reach the same temperature for proposed aerogel reinforcement material. This indicates that a firefighter will receive instant burn on contact in 30 s if only the commercial reinforcement material is used. It was measured that, without any reinforcement material even when only the aerogel nonwoven is used instead of current batting material, a firefighter will have 86 s before feeling any pain, 107 s before receiving first-degree burn and will have 2 and half minutes before theoretically receiving second-degree burn at the same condition. Thus, a firefighter will gain more than 1 min of escape time to withdraw from a danger situation, where it is only 5 s for existing thermal liner and reinforcement material. Performance was also evaluated against fabric thickness and weight, air permeability, resistance to one-way liquid transfer, moisture management, moisture vapour transfer and degree of evaporative cooling. The advantages and disadvantages of proposed combination have been discussed and it was concluded that the use of aerogel reinforcement can significantly increase the protective performance of FPC. Aerogel nonwoven substrate is lighter and has excellent compressive heat resistance as a reinforcement material, and also superior thermal performance compared to the existing commercial thermal liner, multilayer batting, and the combination of face cloth, thermal liner and moisture barrier for a firefighter garment.HighlightsAerogel nonwoven (A) showed superior performance over existing reinforcement material (Rinf) and thermal liner (F+B1) for firefighter’s protective clothing. In particular, aerogel nonwoven has Over eight times more thermal resistance than ‘Rinf’;Excellent compressive heat resistance before receiving burn (A = more than 2.5 min, Rinf = 19 s);Better air permeability (A = 12.4 mL/cm2/s@50 Pa, Rinf = Nil); andEnhanced evaporative cooling (Ret of A = 17.5 Pa m2/W, Rinf = Infinite).

A Comparative Study of the Mechanical Properties of Jute Fiber and Yarn Reinforced Concrete Composites

ABSTRACT A relatively better performance of jute fiber and yarn reinforced concrete composites can open up a wide access to application of natural resources in concrete strengthening. In order to achieve this goal, an experimental investigation on the flexural, compressive and tensile strengths of Jute Fiber Reinforced Concrete Composites (JFRCC) and Jute Yarn Reinforced Concrete Composites (JYRCC) has been conducted. To draw a specific conclusion, the mix ratios of 1:1.5:3 and 1:2:4 (by volume) of concrete have been maintained with incorporation of jute fiber and yarn in concrete mortar having different cut lengths with distinct volumetric ratios. Finally, a comparison of the JFRCC and JYRCC strength increments with respect to the plain concrete has been investigated. A significant increment of compressive, flexural and tensile strength was observed only for a short cut length having a low volumetric ratio, where JYRCC increment value was always found progressive. A far more regular arrangement and adequate mixture of JYRCC was also visualized compare to JFRCC in concrete mortar. All the principal increment values were found only in case of JYRCC with a mix ratio of 1:1.5:3. So, it can be concluded that the presence of jute yarn and more cement content can strengthen the concrete to a great extent.

Advances and applications of chemical protective clothing system

Protection is obligatory for the safety of people in certain occupations where they might be exposed to hazardous chemicals. This review provides an overview of chemical protective clothing, along with its necessity during industrial and military operations as well as in response to acts of terror. Moreover, chemical protective or barrier suits are illustrated and explained including their types, selection processes based on chemical hazards, working environments, and various materials available for the fabrication of effective barrier clothing. Additionally, this review elucidates current research gaps, while underscoring the challenges facing recently developed chemical protective clothing, by compiling relevant research onto a single platform. Besides, this review includes and delineates future trends in chemical protective outfits based on electro-spun nano-fibre technology involved in both detection and decomposition of poisonous chemical agents that come in contact with clothing material, and the integration of selectively permeable membrane technology to discriminately block hazardous chemicals.

Needleless Electrospinning and Electrospraying of Mixture of Polymer and Aerogel Particles on Textile

Needleless electrospinning and electrospraying of aerogel particles in comparatively lower electric voltage (9 kV) have been demonstrated in the paper. Aerogel particles were dispersed in polymer solution and then needlelessly electrospun/sprayed by creating high electric charge at the syringe tip using a curved wire. FTIR spectra and SEM images proved that aerogel particles were deposited onto the base textile. In case of electrospinning, a nanofibre web holding the aerogel particles covered the fabric surface, whereas in case of electrospraying, aerogel particles deposited with the microdroplets of the polymer. The electrospraying process showed great potential for fabric surface functionalization due to the high amount of particle deposition on fabric. The new approach can be applicable for transferring other particulate materials on fabric surface through needleless electrospinning and electrospraying processes.

Contributions of various transmission paths to speech privacy of open ceiling meeting rooms in open-plan offices

Installing open ceiling meeting rooms inside a large open-plan office provides a solution to increase speech privacy and to reduce speech disturbance in the office. The open ceiling meeting rooms have advantages of low cost construction and flexibility, but have lower speech privacy than that of enclosed rooms due to the open ceiling. Existing research shows that many factors should be taken into account to achieve good speech privacy in open-plan offices and improving only one of these factors may result in little improvement, so it is important to distinguish contributions of different acoustic transmission paths of open ceiling meeting rooms in open-plan offices. This paper proposes an impulse response separation method to quantify contributions of various acoustic paths of open ceiling rooms on speech privacy in open-plan offices. The method is verified with simulations based on the Odeon software and the experiments carried out in 3 different types of rooms. Finally, the proposed method is applied to the Fabpod, a semi enclosed meeting room located in a large indoor office at the Design Research Institute of the RMIT University, to obtain the contributions of different acoustic transmission paths to its speech privacy. The method proposed in this paper and the knowledge obtained are useful for architects to improve the acoustic performance of the next generation Fabpods which are now under design at RMIT University.