Wet Texturing Research Articles

The Mechanism of the Air-Jet Texturing: The Role of Wetting, Spin Finish and Friction in Forming and Fixing Loops

A comprehensive review of the roles played by the airflow, wetting and spin finish on the air-jet texturing process is given. The results of an experimental investigation of the air-jet texturing process using residual spin finish, yarn-to-yarn static and kinetic friction, filament strength, filament diameter, and on-line tension measurements and high-speed cine-photography are reported. Filament yarn motion in different regions of the texturing nozzle during dry and wet texturing was analyzed. During the study it was found that water acted as lubricant to reduce friction between the filaments in the wet texturing process as the filament yarn traveled through the nozzle enabling easier relative motion of the filaments resulting in enhanced entanglement. Wet texturing also reduced spin finish on the yarn surface, which in turn, caused an increase in static friction between the filaments of the textured yarn resulting in better fixing of the loops and consequently superior yarns.

Real-time simulation of physically based on-surface flow

Although many papers have been published in the field of fluid simulation, little attention has been paid to on-surface flow involving wetting and stain transportation as well as erosion and deposition phenomena. In this paper, we introduce nonzero divergence in the mass equation of Navier–Stokes equations to simulate water penetration from on-surface flow into substrate material. Also, the volume of fluid method is adopted to track the free surface. With a computation of the actual amount of absorbed water we render the wetting effects with fully dry and fully wet texture images simultaneously. Using our model, the on-surface flow that accompanies water absorption can be simulated realistically in real time with OpenGL preview rendering. Experimental results illustrate that our model can be widely applied to solve various problems related to on-surface flow.

Effect of urchin size and diet on gonad yield and quality in the green sea urchin ( Strongylocentrotus droebachiensis)

A 6-week experiment (August 10 to September 21, 1999) was conducted to determine the effect of urchin size and diet on gonad enhancement of the green sea urchin Strongylocentrotus droebachiensis. Sea urchins were collected from the wild and divided into four size classes—30.0–39.9, 40.0–49.9, 50.0–59.9, and 60.0–73.0 mm test diameter—each size group being split into two dietary treatments [prepared feed or kelp ( Laminaria longicruris and/or Laminaria digitata)]. The experiment was a 4×2 completely crossed design. A number of gonad attributes were quantified at the beginning and end of the experiment including: wet weight, percent yield, percent water, colour, texture, firmness, and taste. The percent change of these variables over the 6-week period was calculated. Colour was assessed subjectively by eye using colour ratings and objectively with a reflected-light, fibre-optic spectrophotometer to generate CIE L* (lightness), a* (hue), and b* (chroma) values. Gonad taste was subjectively evaluated at the end of the experiment. Results from experimental sea urchins were compared and contrasted with those of wild specimens collected from the source population at the end of the experiment. Percent gonad yield at the end of the experiment and percent increase in percent gonad yield over the 6-week period was significantly greater in urchins fed the prepared diet than in those fed kelp. Percent gonad yield was highest in the 40.0–49.9 mm group, followed closely by the 50.0–59.9 and 30.0–39.9 mm size groups, whereas percent increase in percent gonad yield decreased with increasing urchin size. Gonad colour at the end of the experiment was significantly better in urchins fed the prepared diet than in those fed kelp (as judged by colour ratings, a*, and b*) and was better in smaller than larger individuals (as judged by colour ratings, L*, and a*). Percent change in gonad colour ratings decreased and percent change in L* and a* increased with increasing urchin size. Urchin size and feed type had no significant effect on gonad texture, but both factors significantly influenced gonad firmness and taste. Gonads of urchins fed the prepared diet were significantly softer and had significantly more water than those fed kelp. Gonad firmness and percent change in firmness increased with increasing urchin size. Kelp-fed individuals produced significantly better tasting gonads than those fed the prepared diet. The largest urchins produced the best tasting gonads of those fed kelp, but the smallest individuals had the best gonad taste of those fed the prepared diet. Overall, considering both gonad quantity and quality factors, sea urchins of 40.0–49.9 mm test size were deemed to be the most promising for gonad enhancement operations.

Texturing industrial multicrystalline silicon solar cells

Three potential techniques for texturing commercial multicrystalline silicon solar cells are compared on the basis of reflectance measurements. Wet acidic texturing, which would be the least costly to implement, produces a modest improvement in reflection before antireflection coating and encapsulation, whereas maskless reactive-ion etching texturing, and especially masked reactive-ion etched ‘pyramids’, generate a larger gain in absorption. After antireflection coating and encapsulation however, the differences between the methods are reduced. Short-circuit current measurements on wet acidic textured cells reveal that there is a significant additional current gain above that expected from the reduced reflection. This is attributed to both light-trapping and oblique coupling of incident light into the cell, resulting in generation closer to the junction.

The Deterioration of Tall Wheatgrass Pastures on Saline Sodic Soils

The deterioration of sown tall wheatgrass (Elytrigia elongata) growing on 3 sodic saline soils was investigated in the Laprida basin, in the center of the Buenos Aires province of Argentina. These soils are known to have poor drainage and high saline levels and support different species associations. On each soil type the native grassland was compared to sown wheatgrass, in terms of plant density and cover and soil physical and chemical characteristics. The 3 soil types reacted differently to tillage. Tillage had little impact on soil type A (typic Natraquoll), a poorly drained soil with a loamy A horizon (14 cm) overlying a silty clay loam. Soil type B (typic Natraquaf), a wet texture contrast soil with bleached horizons has characteristics that are likely to severely limit plant growth. The sowing of wheatgrass increased ground cover by live vegetation on this soil type. This contrasted with soil type C (typic Natralboll), a saline soil with an organic matter-rich but thin (8 cm) A horizon. In this soil, the plant density declined and other components such as pasture cover also declined with time. This pasture deterioration was attributed to several soil factors including decreased organic matter content and increased soil bulk density. It was concluded that the varied performance of wheatgrass sown pastures was a function of the different inherent characteristics of the soils.

Neps in Air-Jet Textured Yarns

We report on the characteristics of two sorts of neps from wet and dry air-jet textured yams and the effects of process variables on their formation. We discuss structural configurations and opening forces using both machine and videographic methods. Wet texturing produces fewer neps at all pressures, but yet counL does increase with increasing pressure, whether the process is wet or dry.

Role of Water in Air-Jet Texturing

Nylon yarns conditioned in different relative humidities were textured in both dry and wet modes, and the effect of these factors on the structure and properties of air textured yarns was investigated. Results suggest that friction plays a more important role than modulus, and the marked improvement in structure and properties of textured yarns brought about by wet texturing despite increased friction due to wetting cannot be ascribed to a reduction in the modulus of filaments. The changes in the fluid behavior inside the jet may be playing a vital role in influencing the texturing behavior of filaments in the presence of water.

Role of Water in Air-Jet Texturing

Polyester multifilament yams with different frictional characteristics have been air textured under both dry and wet texturing conditions. Wet textured yams are more stable and have higher bulk, and the surface structure of these yarns shows higher loop frequency, lower loop height, and a higher percentage of protrudes and closed and crossed loops for feeder yams with similar frictional characteristics. For comparable values of dry and wet friction, yams textured after prewetting are far superior in properties than yams textured in the dry state. The study clearly demonstrates that the effect of prewetting is not confined only to the lubricating action of water.

Characterization of the Structural Integrity of Air-Jet Textured Yarns

We have developed a method to characterize the stability of air textured yams with repeated load testing using an Instron tensile tester. We compare the instability values obtained with other methods with those using this method. We also assess the influence of process variables such as overfeed, air pressure, dry and wet texturing, and heat stabilization on the structural integrity of air textured yams with the different methods. We have observed that the test method that uses recovery from a given load as a criterion for yarn instability provides a more realistic assessment of structural integrity than the method that uses an extension percentage at a given load.