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1.
Studies on reduction of yarn hairiness by nozzles in ring spinning and winding by airflow simulation
Reduction of yarn hairiness by nozzles in ring spinning and winding is a new approach. Simulation of the airflow pattern inside
the nozzles provides useful information about actual mechanism of hairiness reduction. The swirling air current inside the
nozzles is capable of wrapping the protruding hairs around the yarn body, thereby reducing yarn hairiness. Since production
rate of winding is very high and the process itself increases yarn hairiness any method to reduce the hairiness of yarns at
this stage is a novel approach. A CFD (computational fluid dynamics) model has been developed to simulate the airflow pattern
inside the nozzles using Fluent 6.1 software. In this study, both S- and Z-type nozzles having an axial angle of 50° and diameter
of 2.2 mm were used for simulation studies. To create a swirling effect, four air holes of 0.4 mm diameter are made tangential
to the inner walls of the nozzles. S- and Z-twisted yarns of 30 tex were spun with and without nozzles and were tested for
hairiness, tensile and evenness properties. The total number of hairs equal to or exceeding 3 mm (i.e. the S3 values) for
yarn spun with nozzle is nearly 49–51 % less than that of ring yarns in case of nozzle-ring spinning, and 15 % less in case
of nozzle-winding, while both the yarn types show little difference in evenness and tensile properties. Upward airflow gives
best results in terms of hairiness reduction for nozzle-ring and nozzle wound yarns compared to ring yarns. Yarn passing through
the centre of the nozzle shows maximum reduction in S3 values. 相似文献
2.
A melt-process was used to prepare high molecular weight Poly(vinyl chloride) (PVC) films without the use of a conventional
plasticizer and heat stabilizer. Rigid PVC powder was swollen with dimethylformamide containing 4∼10 vol% water to reduce
its melting temperature. The swollen powder was pressed at a relatively low temperature of 75∼125 °C to form a film shape,
and then washed and dried. The visible light transmittance, X-ray diffraction, density and the tensile properties of the resulting
films were examined to estimate the success or failure of film formation. The films could be produced by not only the melt-process
but also a compression-process using the rigid, highly swollen PVC powder. The resulting films had no voids, which are generally
observed in PVC products formed by a solution process. The minimum temperature for these processes decreased with decreasing
water content in the mixture: The minimum temperatures according to the water content in the mixture to produce faultless
films through the melt-process were 4 %–105 °C, 6 %–115 °C, 8 and 10 %–125 °C, while those through the compression process
were 4 %–95 °C, 6 and 8 %–105 °C, 10 %–115 °C. 相似文献
3.
Spandex has been successfully applied on modified worsted spinning system to produce spandex core spun yarn. However it’s
difficult to produce wool/spandex core-spun yarn on woolen spinning system with the same modified device because the drafting
device of the two systems is quite different. A new method is introduced to apply spandex on woolen spinning system in this
paper. Core-spun yarn produced in this way has good appearance and quality by comparing with normal yarn. A series of experiments
were carried out to study the influence of spandex drafting ratio and yarn twist factor on tensile properties and elasticity
of core-spun yarns. The results indicate that core-spun yarn with spandex drawing ratio of 2.5 and twist factor of 13.63 has
highest value of tenacity and breaking elongation. 相似文献
4.
In this research, possibility of producing and processing antibacterial organic/inorganic nanocomposite polypropylene filament
yarns for permanent antimicrobial efficiency has been investigated. First PP powder and inorganic nanocomposite filler were
mixed in a twin screw extruder and modified masterbatch was produced. Continuous filament yarn was made by a pilot plant melt
spinning machine from the blend of PP granule and various blending contents of the prepared masterbatch. Pure PP and all other
combined samples showed acceptable spinnability at the spinning temperature of 240 °C and take-up speed of 2000 m/min. After
producing as-spun filament yarns, samples were drawn, textured and finally weft knitted. Physical and structural properties
of as-spun and drawn yarns with constant and variable draw ratios were investigated and also tensile and crimp properties
of textured yarns were evaluated. Moreover, the DSC, SEM, FTIR techniques have been used for characterization of samples.
Finally antibacterial efficiency of knitted samples was evaluated. The experimental results indicated that the maximum crystallinity
reduction of modified drawn yarns has reached to 5 %. The observed improvement in the tensile properties of modified as-spun
yarns compared to the pure PP was significant. Drawing process improved generally the tensile properties of as-spun yarns.
Tensile properties of modified textured and drawn yarns were higher than the pure PP. An optimum of antibacterial activity
has been observed in the sample containing 0.75 wt% of nano-filler. It is interesting that the optimum of tensile properties
has been also obtained for the sample with maximum bioactivity. 相似文献
5.
Manufacture technique and electrical properties evaluation of bamboo charcoal polyester/stainless steel complex yarn and knitted fabrics 总被引:1,自引:0,他引:1
Jia-Horng Lin An-Pang Chen Chin-Mei Lin Ching-Wen Lin Chien-Teng Hsieh Ching-Wen Lou 《Fibers and Polymers》2010,11(6):856-860
There are derivative problems of electromagnetic wave radiation accompanying the advances of science and technology nowadays
and secure protections are also emphasized gradually. To shield these electromagnetic wave radition jeopardizing people’s
health, in this study, stainless steel wires were the core yarn and bamboo charcoal polyester textured yarns were the wrapped
yarn. The bamboo charcoal polyester/stainless steel (BC/SS) complex yarns were manufactured using a rotor twister machine.
The BC/SS complex knitted fabrics were woven with the complex yarns employing a circular knitting machine. Three manufacture
parameters were the wrapped amount of the complex yarn (2 to 6 turns/cm), the lamination amount of the knitted fabrics (1
to 6 layers) and lamination angles of the knitted fabrics (0°/0°/0°/0°/0°/0°, 0°/45°/90°/−45°/0°/45°, and 0°/90°/0°/90°/0°/90°).
The knitted fabric exhibited the lowest surface resistance 32.3 Ω/sq. Optimum electromagnetic shielding effectiveness (EMSE)
was 45 dB when the knitted fabrics were with 0°/45°/90°/−45°/0°/45° laminating in 0.51 GHz. 相似文献
6.
This paper is aiming to develop high shrinkable differential shrinkage and mixed fibre nylon composite yarns by applying the
high shrinkable polyester manufacturing technology. The wet and dry thermal shrinkages and mechanical properties of developed
nylon composite yarns are measured and discussed with processing factors in the spinning and texturing processes. And the
effects of the processing factors on the physical properties of high shrinkable nylon composite yarns are investigated. For
this purpose, twenty seven nylon 30d/12f SDY were prepared with variation of spinning temperature, 2nd godet roller temperature
and draw ratio on the spinning machine. The optimum spinning condition which showed maximum wet thermal shrinkage and stress
was determined and high shrinkable nylon 30d/12f SDY spun under this optimum condition used as a core and three kinds of regular
nylon filaments used as sheath were processed on the texturing machine with variation of 1st and 2nd heater temperatures.
The optimum texturing process condition was decided through analysis of dry thermal shrinkage of these core and sheath nylon
filaments. Finally, high shrinkable differential shrinkage and mixed fibre nylon composite yarns were made under the optimum
texturing condition on the texturing machine, its wet thermal shrinkage was 13.8 %, which was much more higher than that of
regular nylon composite yarns. The differential shrinkage effect of the developed nylon composite yarns was found in the yarn
surface and cross section profiles by microscope and SEM. 相似文献
7.
Composite woven fabric satisfies what people require. Bamboo charcoal (BC) has been identified as a multifunctional material
that has far-infrared ray, anions, deodorization and etc. BC fibers and yarns were made of bamboo charcoal powders and have
further become a pervasive materials used in textile industry. In this study, cotton yarns, stainless steel/cotton (SS/C)
complex yarn, bamboo charcoal/cotton (BC/C) complex yarns were woven into the plain, twill and Dobby composite woven fabrics.
The warp yarn was composed of cotton yarns, and the weft yarn was made up of BC/C and SS/C complex yarns with a picking ratio
of 1:1 and 3:1. Thermoplastic polyurethanes (TPU) film was then attached to the composite woven fabrics, forming the BC/SS/TPU
composite woven fabrics. Tests of electromagnetic shielding effectiveness (EMSE), far-infrared emissivity, anions, water resistance,
and water vapor permeability measured the single-layer, two-layer and four-layer composite woven fabrics, obtaining a far-infrared
emissivity of 0.95 by 39.8 counts per minute, an anion count of 149 amount/cc, an EMSE of −11.87 dB under frequency of 900
MHz, a surface resistivity of 8×10−6 Ω/square, a water resistance of −8219 mmH2O, and water vapor permeability of 989 g/m2·h and 319 g/m2·24 h in accordance with JIS L 1099 A1 and ASTM E96 BW. 相似文献
8.
Yarn tension is a key factor that affects the efficiency of a ring spinning system. In this paper, a specially constructed
rig, which can rotate a yarn at a high speed without inserting any real twist into the yarn, was used to simulate a ring spinning
process. Yarn tension was measured at the guide-eye during the simulated spinning of different yarns at various balloon heights
and with varying yarn length in the balloon. The effect of balloon shape, yarn hairiness and thickness, and yarn rotating
speed, on the measured yarn tension, was examined. The results indicate that the collapse of balloon shape from single loop
to double loop, or from double loop to triple etc, lead to sudden reduction in yarn tension. Under otherwise identical conditions,
a longer length of yarn in the balloon gives a lower yarn tension at the guide-eye. In addition, thicker yarns and/or more
hairy yarns generate a higher tension in the yarn, due to the increased air drag acting on the thicker or more hairy yarns. 相似文献
9.
Poly(butylene terephthalate) sheets were prepared by roller-drawing method with various draw ratio. The drawing temperature
is 100 °C and draw ratios were varied 2, 2.5, 3, 3.5 and 4. The effect of draw ratio on the crystal structure, the molecular
orientation, dynamic viscoelastic properties, sonic modulus and tensile properties of the roller-drawn PBT sheets were investigated.
In WAXD results, with increasing of the draw ratio, (010) and (100) planes of preferred orientation have the strongest intensity
on the equator. In the meridional scans, it was confirmed that α and β crystal co-existed in the roller drawn PBT sheets with
various draw ratio. Uniaxially roller-drawn PBT sheets clearly increased orientation along the stretched direction at high
draw ratio. And the four-methylene groups of PBT orient along the surface of the sheet. The mechanical properties of PBT sheets
were improved by orientation-induced crystallization during roller drawing process at 100 °C. 相似文献
10.
The structure development and dynamic properties of fibers produced by high-speed spinning of P(EN-ET) random copolymers were
investigated. The as-spun fibers were found to remain amorphous up to the spinning speed of 1500 m/min, and subsequent increases
in speed resulted in the crystalline domains containing primarilyα crystalline modification of PEN. Theβ modification was not found up to spinning speeds of 4500 m/min. On the other hand, annealing of constrained fibers spun at
the 2100 m/min at 180, 200, and 240°C exhibitedβ-form crystalline structure, while the annealed fibers spun in 600–1500 m/min range exhibited dominantlyα-form. Howeverβ-form crystals disappeared above the spinning speed of 3000 m/min. With increasing spinning speeds from 600 to 4500 m/min,
the storage modulus of as-spun fibers increased continuously and reached a value of about 10.4 Gpa at room temperature. The
tanδ curves showed theα-relaxation peak at about 155–165°C, which is considered to correspond to the glass transition. Theα-relaxation peaks became smaller and broader, and shift to higher temperatures as the spinning speed increases, meaning that
molecular mobility in the amorphous region is restricted by increased crystalline domain. 相似文献
11.
E. Winkler 《Potato Research》1971,14(1):1-18
Zusammenfassung Das Photosyntheseverm?gen der Kartoffelbl?tter h?ngt von der Beleuchtungsst?rke und Blattemperatur ab, das Optimum liegt zwischen
16 und 20°C. Die CO2-Bindung ?ndert sich entsprechend dem Blattalter, so dass man physiologisch Jungbl?tter, erwachsene Bl?tter und Bl?tter im
Abbauzustand unterscheiden muss. Erwachsene 2–3 Monate alte Bl?tter sind am leistungsf?higsten, assimilieren bei 10.000 Lux
und 16°C um 30 mg CO2, bei 50.000 Lux und 20°C 48–50 mg CO2/g.h. Gelbgrün verf?rbte bl?tter leisten nur mehr 60–40%, Jungbl?tter etwa 60–80% obiger Werte. Die Blattatmung, die Atmung
der Sprosse und Knollen sinkt mit der Reifung ab.
Man kann den Stoffgewinn in monatlichen Bilanzübersichten aus Netto-Photosynthese und einzelnen Atmungskomponenten bestimmen.
Monatsmittel um 17°C (mittlere Maxima um 23°C) sind für die Stoffproduktion optimal, Temperaturzunahme um 2°C (auf 19°C, 21°C)
senkt den Reingewinn jeweils um 20–27%.
Für Produktionsanalysen und Sortenbeurteilungen müsste neben dem Photosyntheseverm?gen vor allem die sortentypisch st?rker
schwankende Blattfl?chenentwicklung und die Blattfl?chenandauer festgestellt werden.
Summary The photosynthetic efficiency (— net photosynthesis in the presence of adequate water) of potato leaves depends on intensity of illumination and leaf temperature. The optimum temperature (at 10,000–50,000 Lux) lies between 16 and 20°C. CO2 uptake varies considerably depending on the age of the leaves. One has, therefore, to distinguish between young, adult and senescent leaves on a physiological basis. Adult leaves, 2–3 months old, are the most efficient, giving a figure of 30 mg CO2/g.h. at 10,000 Lux and 16–17°C, and 48–50 mg CO2/g.h. at 50,000 Lux and 20°C. Yellowing leaves reach only 40–60% of these figures and young leaves 60–80% (Fig. 1–3). There is a close relationship between age and respiration level, the latter decreasing with maturity. Individual values for different temperatures are given in Tables 1–5. Dry matter production, because of its dependency on average monthly air temperature (monthly mean and mean maximum), can be determined by drawing up a monthly balance sheet of net photosynthesis and respiration loss. The optimum temperature for dry matter production is a monthly mean of 17° and a mean maximum of about 23°C. If the mean temperature increases to 19° (with a mean maximum of 25°) or 21° (with a mean maximum of 27°C), net production always decreases by about 20–27%. For production analysis and varietal evaluation, both leaf area development and duration, which vary greatly between varieties, must be determined in addition to photosynthetic efficiency.
Résumé L'efficacité photosynthétique (photosynthèse nette avec des approvisionnements suffisants en eau) de feuilles de pomme de terre dépend de l'intensité de la lumière et de la température de le feuille. L'optimum de température se trouve entre 16 et 20°C (à 10.000, 50.000 Lux), le prélévement de CO2 varie beaucoup et dépend de l'age de la feuille. Considérant la physiologie, on doit cependant faire la distinction entre feuilles jeunes, adultes et agées. Les feuilles adultes-vieilles de 2 à 3 mois- sont les plus actives à 10.000 Lux, 16–17°, 30 mg CO2/g.h., à 50.000 Lux, 20° 48–50 mg CO2/g.h. Les feuilles jaunissantes réagissent seulement de 40 à 60%; Les feuilles jeunes atteignent environ 60 à 80% des valeurs des feuilles les plus efficients (Fig. 1–3) en raison de leur importante respiration. La respiration des feuilles, bourgeons et tubercules dépend fortement de l'age; celle-ci décro?t avec la maturité (Tableau 1–5, valeurs individuelles à différentes températures). La production de matière sèche peut se calculer sur base de la photosynthèse nette mensuelle et les pertes par respiration sur base de leur dépendance de la température moyenne mensuelle (maxima moyens mensuels et température moyenne mensuelle). La température moyenne mensuelle de l'air de 17°C est optimale pour la production de matière sèche et les maxima moyens d'environ 23°C. Si les températures atteignent 19°C (maxima à 25°C) ou 21°C (maxima moyens 27°C) la production nette diminue toujours de 20 à 27%. Outre l'efficience photosynthétique, le développement foliaire et la durée des stades spécifiques—qui varient fortement avec les variétés—doivent être pris en considération pour l'analyse de la production et l'évaluation des variétés.相似文献
12.
Jane Harwood Paul McCormick Dennis Waldron Romano Bonadei 《Industrial Crops and Products》2008,27(1):22-28
Due to recent changes in EC subsidies for flax cultivation it has been difficult to grow short fibre flax profitably in the UK. The Texflax project aimed to demonstrate that high quality flax fibre can be produced and processed on short fibre cotton spinning systems. Initially 92 flax accessions were cultivated on test sites in the UK over three growing seasons to explore the range of fibre diameter found in fibre flax. The efficacy of applying a translocating herbicide at different stages of plant maturity for optimum fine fibre production was explored. A range of factors indicated that application at the midpoint of flowering stage is favourable for the desiccation of flax and onset of retting. Fibre was caustic extracted using a laboratory method developed at De Montfort University, and fibre evaluated in terms of diameter, length, consistency and cleanliness. At the end of the project five accessions from the original 92 were chosen as producing optimal quality fibre suitable for high value textile end uses. Improved agronomy and subsequent processing enabled yarns with a 50:50 cotton:flax blend to be spun at 26 N m yarn count, the normal blend ratio for this count being 70:30. The yarn properties show an improvement when compared to standard products and finer quality fabrics have been prepared using the yarns. 相似文献
13.
In this work, the effect of optimum drafting condition on the drafting behavior and yarn quality of the bamboo charcoal-modified
fiber blended spun yarns were studied. We measured the drafting force and drafting force variance, CV% of the bamboo charcoal-modified
Polyester/Cotton (BCP/C) blended roving and bamboo charcoal-modified Rayon/Cotton (BCR/C) blended roving to examine the influence
of the roller gauge and drafting ratio on drafting behavior and yarn quality. We understand that the drafting force of the
bamboo charcoal-modified fiber blended roving follow the same trend as that for the regular P/C and R/C blend roving. However,
the drafting force presents some difference in characteristics between these bamboo charcoal-modified fiber blended rovings.
To correlate the drafting force variation, CV% and the bamboo charcoal-modified fiber blended spun yarn properties, we evaluated
the yarn quality and investigate the yarn quality index in conjunction with the break drafting ratio. Therefore, in this work,
we can obtain the best optimum drafting conditions for bamboo charcoal-modified fiber blended spun yarns; for the 19.7 tex
of BCP70/C30 blend spun yarn was under the roller gauge of 54 mm at the draft ratio of 1.3, whereas, for the 19.7 tex of BCR40/C60
blend spun yarn was under the roller gauge of 54 mm at the draft ratio of 1.2. 相似文献
14.
Jianxin He Yuman Zhou Kun Qi Lidan Wang Pingping Li Shizhong Cui 《Fibers and Polymers》2013,14(11):1857-1863
In order to fabricate continuously twisted nanofiber yarns, double conjugate electrospinning had been developed using two pairs of oppositely charged electrospinning nozzles. The principle and process of this novel yarn spinning method were analyzed, and the effect of applied voltage, nozzle distance between positive and negative, solution flow rate and funnel rotating speed on the diameters, twist level and mechanical properties of resultant PAN nanofiber yarns were investigated in this paper. The results indicated that electrospun nanofibers aggregated stably and bundled continuously at the applied voltage of 18 kV, the nozzle distance of 17.5 cm between positive and negative, the overall flow rate of 3.2 ml/h and the flow ratio of 5/3 for positive and negative nozzles. The resultant nanofiber yarns had favorable orientation and uniform twist distribution, and the twist level of nanofiber yarns increased with the increase of the ratio of funnel rotating speed and winding speed. The diameters and mechanical properties of nanofiber yarns depended on their twist level. The diameters of prepared PAN nanofiber yarns ranged from 50 µm to 200 µm, and the strength and elongation of PAN nanofiber yarns at break were 55.70 MPa and 41.31%, respectively, at the twist angle of 41.8 °. This method can be also used to produce multifunctional composite yarns with two or more components. 相似文献
15.
Core spun yarns are applied for various purposes that especially require the multi-functional performance. This research reports
on the core spinning effect on the yarn strength. We prepared various core yarns by combining different kinds of high tenacity
filaments in core with cotton staples in sheath with various twist levels in the ring spin system. And the tensile strength
was tested to investigate the contribution of the core-sheath structure to the core yarn strength. The influence of the twist
level was also checked up on the relationship between the core-sheath structure and the yarn strength. Results turned out
that the core-sheath weight ratio had influence on the tensile properties of the ring core-spun yarns in different ways according
to the core filaments used for the yarn. Increasing the twists yielded a monotone decreasing strength for the aramid and the
basalt core yarns, while the PET core yarns showed almost unchanged strength, which could be ascribed to the extensional property
of the filaments. 相似文献
16.
The deformation of dispersed polystyrene (PS) droplets in immiscible polypropylene (PP) matrices during melt spinning of blend fibers were simulated by adopting the droplet deformation criteria. The ratios of number-average length to diameter were measured through morphology analysis, and compared with the simulated values. It was found that the adopted deformation models described the deformation behavior of the dispersed droplets during melt spinning very well. Dispersed droplets in the center of the fiber tend to be stretched longer than those of near to the surface, due to the radial temperature gradient during fiber formation. Moreover, combining with the rheological studies of raw materials, a theoretical relation between temperature and deformation was established and used to determine the radial temperature differences along the spinning line. It was found that the radial temperature gradients vary from 0.22 to 0.35 °C/μm at 40 cm beneath to the spinneret at the discussed take-up velocities. 相似文献
17.
The effect of spinning parameters on core-spun yarns properties manufactured using three-strand modified method (TSMM) was analyzed. Of the various spinning parameters, strand spacing, yarn linear density and yarn twist have a crucial effect on core-spun yarn properties. To achieve the objectives of this research, general physical properties of core-spun yarns together with existing standards were thoroughly studied. First of all, the strand spacing and yarn linear density were optimized. Afterwards, the effects of variation of yarn twist and sheath roving linear density on core-spun yarns properties were investigated. Finally, the physical and mechanical properties of TSMM yarns were compared with those of siro and conventional ring core-spun yarns counterparts. It was found that, the best strand spacing and yarn linear density to produce core-spun yarns are 8 mm and 45 tex, respectively. Results showed that, tenacity of TSMM yarns increases up to a certain twist level beyond which it reduces. The result confirmed that 45 tex yarns produced by three rovings of the same count are superior with regards to tenacity and hairiness. The optimized yarns produced by three-strand modified method enjoy superior physical and mechanical properties in comparison to the ring and siro core-spun yarns. 相似文献
18.
Summary Sprout growth in a range of European cultivars was studied over two seasons at constant temperatures from 2 to 25°C, with
an additional 33 (day)/22°C (night) treatment in the second season. There were only minor differences in the response of the
cultivars and the optimum for sprout growth was at 15–18°C in all cases, when measured over an extended period, but initially
sprout growth was more rapid at 23–25°C. Sprout growth at 23–25°C was frequently arrested by sub-apical necrosis, and at these
temperatures the sprouts remained short enough for the tubers to be planted by hand without desprouting. 相似文献
19.
Orthogonal experimental design (I) and (II) were used to study optimum coagulation technology in wet spinning of high molecular weight PAN nascent fiber. Relationship between shape factor (De) and coagulation conditions such as coagulation bath concentration, temperature, and minus draw ratio was investigated to obtain nascent fiber with the minimum De value and smooth surface morphology. The nascent PAN fiber fabricated at the conditions of 80 wt% coagulation bath concentration (in this paper, the coagulation bath concentration refers to the mass concentration of DMSO in coagulation bath), 0 % minus draw ratio, and 40 °C coagulation bath temperature has the smallest fiber diameter, the most circular cross sectional (minimum shape factor) and smooth surface morphology, and the maximum density, which resulted in the most excellent mechanical properties of nascent PAN fiber. 相似文献
20.
《Industrial Crops and Products》2006,23(3):235-243
Sunnhemp is a coarse, strong and stiff bast fiber similar to jute fiber but not considered by textile technologists for the purpose of spinning into yarn, which can be further woven into fabric. The objective of this study was to spin 100% Sunnhemp fibers in to different yarns of same count on a jute spinning system by using different number of passages of carding and drawing to find how the structural changes in the fiber after each stage mechanical processing. To observe structural changes in the fiber, random sampling method was used to collect the fiber samples at various stages of processing and analysis of each fiber was done using microscope. It was found that a lot of changes occur in the fiber structure due to mechanical processing. The structural details about the fiber entity are depicted in the article. Further, correlation was established between various fiber parameters such as fiber length, fiber diameter and fiber number of branches. Finally, an exponential frequency distribution of the fiber lengths for various stages in the spinning process was calculated. This curve explains how the degree of individualization increases as the fiber length decreases and makes the fiber spinnable into better quality yarn. 相似文献