Handle Properties Research Articles

Preparation and Characterisation of Polyacrylic Acid Leucaena Gum as a Thickener in Reactive Dye Printing Pastes

Polyacrylic acid-leucaena gum was prepared by the polymerisation of acrylic acid on leucaena gum using potassium persulphate as initiator. The rheological properties of the gums and their utilisation as thickening agents in printing cotton fabrics with reactive dyes were investigated. It was found that polyacrylic acid-leucaena gum pastes are characterised by a non-Newtonian pseudoplastic behaviour. The apparent viscosity depends on the amount of acrylic acid. Cotton fabric samples printed with cibacron blue 3R acquire soft handle and colour fastness properties nearly identical with those printed using sodium alginate paste; the highest colour strength was obtained using a mixture of polyacrylic acid/leucaena gum with sodium alginate at a ratio of 1:3 w/w.

Preparation and Characterisation of Polyacrylic Acid Leucaena Gum as a Thickener in Reactive Dye Printing Pastes

Polyacrylic acid-leucaena gum was prepared by the polymerisation of acrylic acid on leucaena gum using potassium persulphate as initiator. The rheological properties of the gums and their utilisation as thickening agents in printing cotton fabrics with reactive dyes were investigated. It was found that polyacrylic acid-leucaena gum pastes are characterised by a non-Newtonian pseudoplastic behaviour. The apparent viscosity depends on the amount of acrylic acid. Cotton fabric samples printed with cibacron blue 3R acquire soft handle and colour fastness properties nearly identical with those printed using sodium alginate paste; the highest colour strength was obtained using a mixture of polyacrylic acid/leucaena gum with sodium alginate at a ratio of 1:3 w/w.

Low Stress Mechanical Properties of Silk Fabric Degummed by Different Methods

Mulberry silk fabric has been degummed by using five different methods (acid, alkali, triethylamine, soap and enzyme) and the results compared in terms of handle properties. Low stress mechanical properties tested on the KESF system have been used to evaluate the hand values. Soap has been taken as the standard method of degumming and the other treatments have been compared with this method. Significant differences in the low stress properties have been observed for the different treatments. Soap, alkali and TEA methods score over the acid and enzymatic methods in terms of handle properties, Low shear and surface properties characterise the acid and enzyme degummed samples indicating non-uniform removal of gum from the interlacing areas. The whiteness index has also been measured.

Handle and Comfort Properties of Woven Fabrics Made from Random Blend and Cotton-Covered Cotton/Polyester Yarns

Two identically constructed cotton/polyester fabrics, one made from polyester staple core/cotton-covered yarn and the other from a random blend yarn, were evaluated for their low-stress mechanical properties and hand quality, following the objective hand evaluation approach developed by Kawabata. Heat energy dissipation through the fabrics under dry and wet contact conditions and their warm-cool contact sensations were measured using Kawabata's new "Thermolabo Device." Comparison of the low- stress mechanical properties revealed that the fabric made of polyester-core/cotton covered yam is more resilient to tensile and compressive deformation and has higher bending rigidity, lower tensile elongation, and lower shear modulus. The same fabric also gives higher values for all four primary hand qualities and for total hand quality associated with a men's summer suit application. For a women's thin dress application, it gives higher values for five out of the six primary hand qualities. It also offers a cooler contact sensation and much less variation in contact sensation along its length . compared to the fabric from the random blend yarn. The amount of heat energy dissipated through the fabric made of cotton-covered yam was lower under dry contact (nonsweating) conditions and higher under wet contact (sweating) conditions, sug gesting that this fabric may have a better thermal comfort value for cold and dry (winter) as well as hot and humid (summer) weather conditions. Energy dissipation along the fabric also varied much less for the material from cotton-covered yarn. This work not only identifies differences in the subjective properties of the fabrics in quan titative terms, but also demonstrates the value of Kawabata's methods for designing and producing superior quality apparel fabrics.

Studies of Nonwovens

The performance characteristics of nonwoven fabrics have been studied as a function of fiber properties, binder properties, and web construction. The particular type of nonwoven selected for study was a web of random-laid base fibers in which randomly placed thermoplastic fibers provide the bonds. The responses studied were those related to rupture, elastic, and handle (aesthetic) properties. Fourteen variables were investigated: Base fiber linear density, base fiber staple length, amount of crimp in base fiber, post-yield extension of base fiber, type of binder, linear density of binder, staple length of binder, binder concentration, mass per unit area of nonwoven, amount of needle looming, number of laminations per web weight, pressure of bonding, temperature of bonding, and time of bonding. The performance characteristics measured as a function of these variables were maximum tenacity at dry and wet conditions, elongation at dry and wet conditions, tear strength, abrasion resistance, elastic modulus at dry and wet conditions, proportional limit at dry and wet conditions, crease recovery, bending length, flexural rigidity, bending modulus, bulk density, and air permeability. Crimp, linear density, and staple length of the base fiber influence rupture, elastic, and handle prop erties, as expected. Binderproperties, other than type, have no effect due to the destruction of the fiber in the bonding process. Bonding conditions, particularly pressure and temperature, are extremely influential in all types of properties. These variables govern the effectiveness of the bonds. Concentration of binder is extremely important to all types of responses since it governs the number and distribution of bonds. Needle looming affects only rupture properties.

Multivariable Studies of Nonwoven Fabrics

The performance characteristics of nonwoven fabrics have been studied as a function of fiber properties, binder properties, and web construction. The particular type of non-woven selected for study was a web of random-laid base fibers in which randomly placed thermoplastic fibers provide the bonds. The responses studied were those related to rupture, elastic, and handle (aesthetic) properties. Fourteen variables were investigated: Base fiber linear density, base fiber staple length, amount of crimp in base fiber, post-yield extension of base fiber, type of binder, linear density of binder, staple length of binder, binder concentration, mass per unit area of nonwoven, amount of needle looming, number of laminations per web weight, pressure of bonding, temperature of bonding, and time of bonding. The performance characteristics measured as a function of these variables were maximum tenacity at dry and wet conditions, elongation at dry and wet conditions, tear strength, abrasion resistance, elastic modulus at dry and wet conditions, proportional limit at dry and wet conditions, crease recovery, bending length, flexural rigidity, bending modulus, bulk density, and air permeability. Crimp, linear density, and staple length of the base fiber influence rupture, elastic, and handle properties, as expected. Binder properties, other than type, have no effect due to the destruction of the fiber in the bonding process. Bonding conditions, particularly pressure and temperature, are extremely influential in all types of properties. These variables govern the effectiveness of the bonds. Concentration of binder is extremely important to all types of responses since it governs the number and distribution of bonds. Needle looming affects only rupture properties.

Fifty tons at one scoop : Power Plant Engineering, Vol. XL, No. 3

The cable shovel excavator is used for primary production in many surface mining operations. A major problem in excavation is the variability of material diggability, resulting in varying mechanical energy input and stress loading of shovel dipper-and-tooth assembly across the working bench. This variability impacts the shovel dipper and tooth assembly in hard formations. In addition, the geometrical constraints within the working environment impose production limitations resulting in low production efficiency and high operating costs. A potential solution to the above problems is the deployment of an intelligent shovel excavation (ISE) technology, with real-time formation identification, recording and knowledge transmission capabilities. This paper advances the ISE technology by developing dynamic models of the cable shovel using the Newton–Euler techniques. The models include the main factors that influence shovel performance including the effect of both linear and angular motions of dipper handle and dipper. A path trajectory is modeled to demonstrate the dynamic velocity and acceleration profiles. Numerical examples show that the critical performance variables include geometrical and physical properties of the dipper and dipper handle, digging strategies and formation properties. The kinematic results show that the critical phase occurs between 1.5 and 2.0 s of a 3-s excavation cycle with occurrence of maximum kinematic effects. The dynamic results also show a similar trend with maximum dynamic effects between 1.5 and 2.0 s. The results also show that the maximum resistive force occurs at 1.625 s within the excavation cycle. At this point the maximum breakout force of the equipment is reached and any increase in the resistive load will require further fragmentation. The results provide appropriate information for excavation planning and execution. These models form the basis for developing dynamic shovel simulators for the ISE technology.