Effect of polyester and elastane linear density on the physical and mechanical properties of dual-core-spun cotton yarns

ABSTRACT

The use of single-core elastic spun cotton yarns is well established in textiles and denim industry but interest in the use of dual-core-spun yarns has started to grow only recently. The aim of this study was to investigate the effect of polyester and elastane linear density on the physical and mechanical properties of dual-core-spun cotton yarns. Yarn samples were prepared on industrial-scale spinning machines using cotton as the sheath fibers and two different linear densities of polyester and three different linear densities of elastane filaments in the core. Statistical analysis of the results revealed that yarn tenacity, elongation, uniformity, and hairiness are significantly affected by the linear densities of both the polyester and elastane filaments in the core, with statistically significant interaction between them. Yarn imperfections (IPI), however, are affected mainly by the polyester denier, while the elastane linear density did not show statistically significant effect on the IPI. Regression equations for different yarn properties were also developed which showed fairly high values of coefficient of determination (R-sq).     

Physicochemical parameters,bioactive compounds and microbial quality of sonicated pear juice

This study was carried out to investigate the effect of sonication on physicochemical parameters and microorganisms of pear juice. Ultrasound processing of fresh pear juice was done at fixed amplitude [70% (500 W) and frequency (25 kHz) for 0, 15, 30, 45 and 60 min at 25 °C. Total soluble solids, pH, titratable acidity and Ca and Mn remained stable, while the cloud value, ascorbic acid, total phenols, total flavonoids, total antioxidant capacity, sugar contents and Na, K, Fe and Mg showed a significant increase. Decreases in microbial population and P and Cu were also observed. It may be inferred that ultrasound processing for 60 min exhibited optimum results in terms of physicochemical and microbial quality.     

Effect of woven fabric structure on the air permeability and moisture management properties

In this study, six different woven samples were produced on air jet loom with two different weave designs (i.e. 3/1 twill and 1/1 plain), three different picking sequences (i.e. single pick insertion (SPI), double pick insertion (DPI) and three pick insertion (3PI)). All the woven samples were singed, desized, bleached and finished together at industrial scale, as a single lot. The effect of these factors on the wetting, wicking and air permeability (AP) of the fabric samples was analysed. It was revealed that the fabric weave design and picking sequence has statistically significant effect on fabric wetting time, water spreading speed and AP of the fabric. It was found that fabrics woven in twill weave design and with simultaneous 3PI give significantly better AP, shorter wetting time and better water spreading rate as compared to plain woven fabrics and those with double or SPI. It could be concluded that the thermophysiological comfort of woven fabrics may be significantly improved simply by selecting a suitable weave design and picking sequence.     

Thermal and thermoelastic problems in dry friction clutch: A comprehensive review

The friction clutch is considered a very important element of machines, as it plays a major role in transferring power from the driving part to the driven part. A common application of the friction clutch is in vehicles to connect between the gearbox and the engine. Fast wear occurs as a result of frictional heating that is generated when the clutch is starting to engage. This wear, in addition to the high thermal stresses, will lead to premature failure in the contacting surfaces. The present review highlights the most important studies of the thermal and thermoelastic problems of friction clutches during the last 10 years to show the challenges that were overcome and also the other challenges that needed to find solutions. The present paper will discuss in detail the influence of the frictional heat generated between contact surfaces during slipping and the main factors affecting the thermal behavior of dry friction clutches, such as sliding speed, friction materials, applied pressure, and so on. Furthermore, significant conclusions and remarks based on the available solutions to the thermal problem of the clutch are presented.     

Experimental and theoretical studies of equilibrium isotherms for pure light hydrocarbons adsorption on 4A zeolite

Experimental and theoretical studies were reported on equilibrium isotherms of pure methane and ethane adsorption on 4A molecular sieve zeolite at 301 K. The experimental equilibria data were measured using the constant-volume method. The Langmuir, the Freundlich, and BET equations were used to fit the pure component experimental data. The results show that both the Langmuir and Freundlich equations correlated the pure component experimental data fairly well with a correlation coefficient of 0.998 and 0.977 for methane and ethane, respectively. The results of this study showed that ethane was more selectively adsorbed than methane on 4A molecular sieve zeolite.     

Optimum ethane recovery in conventional turboexpander process

Ethane recovery in a conventional turboexpander process is optimized considering different demethanizer pressures and different feeds: a lean gas and a rich one. The design variables are varied, while meeting process constraints, in order to find the optimum conditions achieving the maximum profit. The analysis covers the whole process including the refrigeration part, and the entire typical demethanizer pressure range. The optimum ethane recovery is compared with the maximum possible recovery for each value of the demethanizer pressure. Recommendations are given regarding the selection of the level of ethane recovery, along with the demethanizer pressure, and refrigeration recovery system.     

Flexural fatigue and failure probability analysis of polypropylene-glass hybrid fibres reinforced epoxy composite laminates

Flexural fatigue tests have been conducted on polypropylene/epoxy composite and its hybrids with glass fibre. Specimens were fabricated in intraply and inter-intraply configurations using the hand lay-up technique. Fatigue tests were performed at a frequency of 25 Hz and zero mean stress. A 20% reduction of the flexural stiffness was taken as a failure criterion. The effects of fibre hybridisation, hybrid configuration and stacking sequence on S–N curves were investigated. The fractured specimens were examined using SEM. Weibull distribution function was used to obtain the failure probabilities and the scatter in the results. Results indicated that hybridising polypropylene fibre with glass improves the flexural fatigue resistance. The fabricated hybrids have economical and specific fatigue strength benefits. The stacking sequence has a great effect on the composite's fatigue resistance. The inter-intraply hybrid laminate with glass fibre layers skin and polypropylene fibre layers core presents the most favourable flexural fatigue behaviour.     

Evaluation of physical and chemical characteristics of newly evolved wheat cultivars

Evaluation of quality characteristics of wheat provides significant feedback to breeders for selection/evolution of the most suitable varieties. Seven advanced wheat cultivars and two commercial varieties were studied for 11 physicochemical characteristics. These cultivars showed significant differences for all parameters except ash content, which showed no significant variation. Test weight ranged between 75.6 kg hl^?1 (NRL‐2005) and 80.5 kg hl^?1 (NRL‐2017). Kernel weight and volume were highest (4.0 g and 3.2 ml) for NRL‐9822 and lowest (3.3 g and 2.6 ml) for NRL‐2005. Biological yield was highest (14 040 kg ha^?1) for NRL‐9822 and lowest (12 380 kg ha^?1) for Takbeer variety. Grain yield varied between 4717 kg ha^?1 (NRL‐01‐7) and 4042 kg ha^?1 (NRL‐9736), non‐grain biomass between 9708 and 8083 kg ha^?1, protein yield between 614.3 and 480.8 kg ha^?1 and harvest index between 34.8 and 30.8%. Moisture content ranged from 7.46 to 9.07%. Gluten and protein contents were highest (39.69 and 13.81%) in NRL‐9736 and lowest (29.78 and 12.70%) in NRL‐9822. Test weight was positively correlated with kernel weight and volume and negatively associated with moisture, protein and gluten contents. Protein and gluten contents had a negative association with kernel weight and volume. Gluten content had a highly positive correlation with protein content. Grain yield was positively correlated with biological yield. Protein yield had a positive relationship with biological and grain yields and a negative association with harvest index. Copyright © 2005 Society of Chemical Industry     

Quasi-resonant-converters-based high-efficiency spindle motor drives for magnetic data storage

Disk drive spindle motors require accurate speed control and highly efficient drive controllers. Small-volume and high-efficiency converters are of particular interest for portable data storage applications. Quasi-resonant voltage controllers are described in this paper and the experimental results are presented. In contrast to the conventional pulsewidth-modulated voltage controller, this technique reduces the switching loss and enables the controller to operate at very high frequencies. Three types of resonant converters are built and tested for the application. A comparison of performance in terms of losses and voltage regulation is given.