Biodegradation of Chemically Modified Jute Fibers

Degradation of lignocellulosic fibers such as untreated jute fibers and those treated with an alkaline solution of neem oil and phenolic resin are studied by monitoring enzyme activities during burial of fibers within a compost of organic soil and animal refuse. Results indicate that biodegradation of fibers is dominated initially by enzymatic hydrolysis of hemicellulose and amorphous cellulose and subsequently by crystalline cellulose degradation. For neem oil and phenolic resin treated fibers, the degradation of hemicelluloses and cellulose were found to proceed at a remarkably slower rate compared to untreated fibers due to relative nonavailability of degradable matter.     

Airbags

In recent years, safety systems such as seat belts and airbags have been one of the fast-growing sectors within the automotive industry. Seat belts and airbags have made driving substantially safer since their introduction. Airbags are safety systems used to cushion the driver or passenger during a collision and reduce bodily injuries. The technology involved in the manufacturing and working of airbags is complex. Since the early stages of development, airbag technology has been undergoing continual evolution in terms of design, materials and performance. Airbags are typically made from woven fabric, which may be coated or uncoated but must be impermeable to gases and flame resistant. In terms of their operation, modern airbags are smart restraint systems, which can tailor the deployment of the airbag according to the crash severity, body size of the occupant and proximity of the occupant to the airbag system prior to deployment. The future of airbags is extremely promising because there are many diverse applications ranging from motorcycle helmets to aircraft seating. In this article, an outline is given of the historical development of airbags and their value in saving lives is illustrated by supporting statistical data. The essential parameters required for airbag yarn and fabric components are discussed in detail. In addition, the processes involved in the manufacture, assembly and testing of airbag systems are explained. The mechanisms and chemical reactions involved in the deployment of different types of airbags are also discussed, and recent developments in airbag design and their possible future applications are reported.     

Development and evaluation of dustless fabrics for medical applications

Dust-free fabrics and garments are essentially used in hospitals to maintain hygiene in operation theatres and also in various other industrial establishments, such as cleaning electronic chip manufacturing rooms. It is also needed for personal health care of allergy and asthma patients. In order to design a dust-free fabric, it is very important to study the characteristics of the textile materials that influence dust attraction. In this work, the dust particle size and its distribution on different types of fabrics with different fibre types have been studied making use of non-conventional instruments. As of today, there is no instrumental technique available for studying the dust concentration on textile substrates. Therefore, there is a need for developing an instrument that would measure dust particle size and their concentration on textile materials. A digital dust analyzer has been developed for this purpose. This instrument is calibrated by standard dust particles that have similar properties as that of atmospheric dust particles. The reference dust particle size falls in the range of 0.1–198 μ m. A set of fabrics were selected to study the effect of fabric properties towards dust attraction. The results revealed that lowest dust accumulation occurs on plain woven 100% polyester fabrics followed by polyester–cotton blends. The dust-less fabrics developed through different techniques such as polyurethane coating, silicone finishing and weaving of metallic filaments showed satisfactory improvement in their functional properties. Polyurethane coated fabrics give best results followed by silicone finish fabrics and metallic yarn woven fabrics. Based on the analysis and understanding of the results, some of the factors influencing the dust affinity of fabrics are established.     

Effect of TiO2 nanoparticles on basalt/polysiloxane composites: mechanical and thermal characterization

In the present investigation, a novel technique has been developed to fabricate composite materials containing TiO₂ nanoparticles, polysiloxane resin, and basalt fabric. A high-intensity ultrasonic probe was used to obtain a homogenous molecular mixture of TiO₂ nanoparticles and polysiloxane resin, thus the nanoparticles were infused into the resin through sonic cavitation. The loading effect of TiO₂ nanoparticles on the thermal and mechanical properties of basalt fabric reinforced polysiloxane composite materials has been investigated. Composite samples were prepared, each using two layers of basalt fabric with TiO₂ nanoparticles loading from 0.5, 1, 1.5, 2, 2.5, and 3% by weight. Size distribution of nanoparticles was observed by particle size analyzer and the prepared fabric nanocomposites were characterized by scanning electron microscopy, dynamic mechanical analysis (DMA), thermo gravimetric analysis (TGA), and differential scanning calorimetry (DSC). Tensile testing was performed as per American standard for testing of materials (ASTM) standards. The dependence of dynamic mechanical parameters E′, E′′, tan (delta), T _g, and heat distortion temperature (HDT) are associated with the filler content and can be controlled by the curing conditions. Tensile results show that 1.5 wt.% loading of TiO₂ nanoparticles in the nanocomposites resulted in highest improvement in tensile modulus compared to the neat system. DMA studies also revealed that 1.5 wt.% doped system exhibits highest storage modulus as compared to the neat and other loading percentages. DSC and TGA studies show that T _g and HDT of the composite increases with the increase in wt.% of nanofillers in the composite. Based on these results, it is clear that miscibility of nanoparticles in the resin is of prime importance with regard to performance.     

Novelty of bamboo fabric

Fabric samples using 100% cotton, 100% viscose rayon, 100% regenerated bamboo viscose fibre and cotton/bamboo viscose blend (60/40) were produced and characterised for hand value and health care applications. The present study shows the results of these woven fabrics in terms of antibacterial, absorbency, ultraviolet protection factor (UPF), static characteristics, moisture vapour permeability (MVTR) and handle and dust catchability. Bamboo fabrics (100%) give better results compared to 100% cotton and 100% viscose fabric in terms of antibacterial property and absorbency i.e. wettability. Bamboo fabric (100%) also shows slightly higher moisture vapour transmission rate than cotton fabric. In the case of UPF, 100% cotton and 100% bamboo give excellent-rated UPF. There is no significant difference between these fabric samples in terms of time to lapse half saturated voltage. Total hand value is higher in the case of viscose and bamboo fabric than cotton fabric. The studies also show that breaking load and extension of bamboo gauze bandages are higher than cotton bandages. Sinking time is faster but absorptive capacity is lower in the case of bamboo gauze bandage than cotton gauze bandage.     

Reconstructing Primary and Secondary Components of PM2.5 Composition for an Urban Atmosphere

Total 360 samples (of 8 h each) of PM_2.5 were collected from six sampling sites for summer and winter seasons in Kanpur city, India. The collected PM_2.5 mass was subjected to chemical speciation for: (1) ionic species (NH⁺ ₄, SO^2– ₄, NO^– ₃, and Cl^–), (2) carbon contents (EC and OC), and (3) elemental contents (Ca, Mg, Na, K, Al, Si, Fe, Ti, Mn, V, Cr, Ni, Zn, Cd, Pb, Cu, As, and Se). Primary and secondary components of PM_2.5 were assessed from speciation results. The influence of marine source to PM_2.5 was negligible, whereas the contribution of crustal dust was significant (10% in summer and 7% in winter). A mass reconstruction approach for PM_2.5 could distinctly establish primary and secondary components of measured PM_2.5 as: (1) Primary component (27% in summer and 24% in winter): crustal, elemental carbon, and organic mass, (2) Secondary component (45% in summer and 50% in winter): inorganic and organic mass, and (3) others: unidentified mass (27% in summer and 26% in winter). The secondary inorganic component was about 34% in summer (NH⁺ ₄: 9%; SO^2– ₄: 16%; NO^– ₃: 9%) and 32% in winter (NH⁺ ₄: 8%; SO²⁺ ₄: 13%; NO^– ₃: 11%). The secondary organic component was 12% in summer and 18% in winter. In conclusion, secondary aerosol formation (inorganic and organic) accounted for significant mass of PM _2.5 (about 50%) and any particulate control strategy should also include control of primary precursor gases.     

Effect of working gap and circumferential speed on the performance of magnetic abrasive finishing process

Magnetic abrasive finishing (MAF) is one of the advanced finishing processes in which workpiece is kept between two magnets, and cutting force is controlled by working gap and magnetic field between the two magnets. MAF setup is designed for finishing cylindrical workpieces and it is mounted on lathe machine. The loosely bounded powder is prepared for experimentation by homogeneous mixing of magnetic powder (Fe powder of 300 mesh size (51.4 μm)), abrasive powder (Al₂O₃ of 600 mesh size (25.7 μm), and lubricant called servospin-12 oil. To investigate the effects of working gap and circumferential speed on material removal, change in surface finish and percent improvement in surface finish, a series of experiments have been conducted using in-house fabricated setup. Based upon the results, in general, material removal decreases by increasing working gap or decreasing circumferential speed of the workpiece. Change in surface finish increases by increasing circumferential speed of the workpiece.     

Theoretical Investigation of Some High‐Performance Novel Amine Azide Propellants

Monomethylhydrazine (MMH) is currently the most widely used hypergolic propellant, due to its high performance and low ignition delay. However, its toxicity is a major concern. The present work aims at developing high‐performance hypergolic fuels that are based on tertiary amine azide functionality. A number of potential amine azide candidates have been proposed, and some of their physical and chemical properties have been computed using state‐of‐the‐art molecular modeling techniques. Gas‐phase heats of formation have been calculated using the CBS‐QB3 method, and the first‐principle COSMO‐RS method has been used to compute heats of vaporization and vapor pressures. A density correlation, based on molecular‐volume calculation, has been established to predict the densities of the candidate molecules. Finally, the liquid‐phase heats of formation and densities have been used to predict the specific and density impulses of the proposed candidate molecules. The results show that many of the molecules proposed here have much higher density impulse than that of MMH, and may be considered for experimental studies.