An experimental investigation of yarn tension in simulated ring spinning

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.     

Morphological aspects of polymer fiber mats obtained by air flow rotary-jet spinning

Fiber mats were obtained by using a modified rotary-jet spinning system, which allows a forced air flow produced by an air compressor to interfere with the polymer jets. The main focus of current studies rely on the range of morphological and dimensional characteristics of fibers that may be expected when using this new technical setup of a rotary-jet based spinning system. In fact, this work represents a proof of concept study regarding the potential of an air flow modified rotary-jet spinning for obtaining continuous fibers and nonwoven mats. The morphological examinations by scanning electron microscopy were proved the efficiency of this technique on obtaining relative homogeneous fiber mats from different raw compositions of pure and admixed, natural and synthetic polymers with different molecular masses and polydispersity degrees, like gelatin, polyurethane, and poly (vinyl chloride). The feasibility of air flow rotary-jet spinning was also tested for simultaneous independent deposition of mixed fiber mats from solutions of two polymers made in different solvents, and it was found that by carefully selecting the ratio of polymers through spinnerets number, this technique could be successfully used even in difficult solvent conditions otherwise incompatible with traditional spinning techniques. The distribution of fiber diameters was varying between nanometer scales (100–700 nm) in the case of pure polyurethane and micrometer ranges (2–12 µm) for gelatin-polyurethane mixed mats, which are convenient for various applications, from dressings and scaffolding to different filter systems. Besides the already known advantages of rotary-jet versus electrospinning, the air flow allows the control of solvent evaporation, extending the applicative range of this technique.     

Effects of spinning processes on HVI fiber characteristics and spun yarn properties

The effects of opening, carding, and repeated drawings on single fiber and bundle cotton characteristics were studied by employing Mantis®, AFIS® and HVI Testers. Some of the significant changes in single fiber properties were found to be due to process parameters as well as the changes in the fiber crimps, parallelness of fibers within HVI beards, and the actual changes in the tensile properties of the fibers. The study showed that the HVI test data taken just prior to spinning had the highest correlation with the yarn tensile properties. Based on the study results, we point out the potential of HVI for future quality and process control in spinning by recommending a set of expanded HVI output that is more scientific and comprehensive for the future control needs.     

Theoretical analysis of the melt spinning process of poly(trimethylene terephthalate) fibers

Profiles development of the melt spinning process of poly(trimethylene terephthalate) (PTT) was simulated by a numerical method. The spinning speed of 3 km/min to 5 km/min was analyzed and the characteristic of PTT spinning process was compared with that of poly(ethylene terephthalate) (PET). Velocity development of PTT was slower than that of PET. Although PTT’s spinning temperature was lower than PET’s, the PTT solidified slower because of a smaller super-cooling and the large specific heat capacity. The diameter profile of PTT decreases gradually in comparison with that of PET. PTT’s strain rate has a broader distribution than PET’s and its maximum ranged from 541 to 570 s⁻¹ for PET and 136 to 149 s⁻¹ for PTT. PTT’s tensile stress was smaller than PET’s.     

纺纱方式对长绒棉高支纱性能的影响

为明确不同长绒棉纤维适纺性能及不同纺纱方式下的成纱质量,以新疆5个长绒棉品种(系)(新海35号、新海53号、新海57号、丰海8号、丰海7号)的纤维为原料,采用普通环锭纺和紧密纺2种纺纱方式,纺100S纯长绒棉纱,并对成纱性能进行测试.结果:与环锭纺相比,紧密纺大大提高了成纱的强伸性能,降低了3 mm毛羽指数,改善了条干...     

Optimization of fiber distribution in spunbond non-woven structure

The mechanical properties of thin spunbond tissues depend on the distribution of fibers in tissues structure. The optimum fiber distribution leads to the fiber mass uniformity spreading in the tissue structure. The present research defines an optimum model of fiber distribution in the tissue structure by using genetic algorithm. To find the applicability of the presented optimization method, some samples have been prepared from Polypropylene fibers (1.5 Den). The mechanical tests have been performed on tissue samples. The results confirmed that the developed model using genetic algorithm can be applied as a reliable method to determine optimum fiber distribution strongly.     

Numerical simulation of fiber strands on condensing effect of suction slot in compact spinning with lattice apron

Compact spinning technology is through the airflow force to get fiber strands to be compacted in the condensing zone. In this paper, it makes a deeper study on the morphological changes and movement process of fiber strands in the flow field of condensing zone. Based on the airflow data in the condensing zone, the geometrical model of single fiber is built, and then the trajectory of single fiber can be got. The difference of trajectory and compact effect of fiber strands is also analyzed in the condensing zone of straight, oblique and deformed suction slots.     

Theoretical analysis on torsion of a fiber with arbitrary cross section

Approximate torsion solutions of a fiber with arbitrary cross section are obtained in the closed form. Two energy methods are applied to torsion problem and very simple formulas for the lower bound and upper bound of torsional rigidity constant are obtained. A large number of special cases of the derived general formulas of torsional rigidity constant find important practical applications in practice. In this paper, only three cases are discussed in detail.     

Exponentially autocorrelated mass distribution along staple fiber yarns

In this work, a series of cotton carded ring-spun yarns of different counts and different twist multipliers is prepared and the mass distribution along the yarns is studied as a random process. The mass autocorrelation coefficients of the coarser yarns are found to be higher as compared to those of the finer yarns and this difference is found to be low at lower twist multiplier of the yarns. The decay of mass autocorrelation at higher distances along the yarns is explained by a double exponential autocorrelation function which raises the probable existence of two highly different random effects that are acting additively on the yarns to decrease the mass autocorrelation at higher distances along the yarns. The finer yarn exhibits faster decay of mass autocorrelation than the coarser yarn, but this difference is low at lower twist multiplier of the yarns.     

Improving the dyeability of poly(lactic acid) fiber using N-Phenylaminopropyl POSS nanoparticle during melt spinning

The dyeability of poly(lactic acid) (PLA) fiber strongly depends on disperse dye structure due to the low dyeing temperature and the short dyeing time. Thus, the dye uptake value of PLA fiber is low for some disperse dyes and is needed to be improved. In the current study, the dyeability of PLA fiber is improved with the addition of N-Phenylaminopropyl polyhedral oligomeric silsesquioxane (AP-POSS) during melt spinning process. The effects of dyeing conditions including dyeing temperature and time, disperse dye type and AP-POSS concentrations are investigated on the dyeability properties of PLA fiber samples. The tensile, thermal and morphological properties of fiber samples are also characterized by tensile testing, differential scanning calorimeter (DSC), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). As the added amount of AP-POSS increases, the percent crystallinity increases and the tensile strength reduces. According to the dyeing results, AP-POSS is very effective for increasing the dyeability of PLA fiber especially for disperse dyes with low dye uptake values.     

Three dimensional fiber orientation distribution in two dimensional flows

The orientation of a fiber suspended in planar or axi-symmetric flow was solved. Direct relation between the single fiber orientation and the orientation distribution was found. It gives a simple way to solve the fiber orientation distribution problem. It is found that the fiber orientation distribution does not depend on the magnitude of the velocity gradient of the flow, but depends on the relative magnitude of the velocity gradient components. In 2D flows, initially random 3D oriented fibers show great probability to align with a specific direction in the flow plane. The fiber orientation distribution evolutions in various 2D flows were also presented in an intuitional way. It provides thorough understanding about the fiber orientation in 2D flows, and functions as a benchmark to those approximations.     

Study on optimum coagulation conditions of high molecular weight pan fiber in wet spinning by orthogonal experimental design

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.     

The non-uniform phase structure in blend fiber. I. Non-uniform deformation of the dispersed phase in melt spinning

By melt spinning of incompatible polymer blends, the deformation of the dispersed phase was investigated in the fiber spinning process, for polypropylene/polystyrene (PP/PS) blend fiber and low density polyethylene/polyamide 6 (LDPE/PA6) blend fiber, respectively. Two kinds of the take-up fiber all exhibit the matrix fibrillar morphology, but with the opposite morphology. For PP/PS take-up fiber, the dispersed PS fibrils were finer in the core than near the surface. On the contrary, the dispersed PA6 fibrils were finer near the surface than in the core for LDPE/PA6 take-up fiber. However, for the special fiber in which the extensional flow was absent, there was the uniform morphology in either PP/PS or LDPE/PA6. Thus, fibrils’ non-uniform deformation, occurred in the drawing process, was considered to be due to the radial non-uniform processing conditions across the spin-line cross-section. The distribution of fibrils’ diameter was also investigated on the whole cross section. Rheological properties of each component were measured by the capillary rheometer. The non-uniform phase structure in blend fiber is a new phenomenon in the extensional flow.     

Preparation,mechanical properties and microstructure of polyoxymethylene fiber through melt spinning and hot drawing by using injection-molding grade resins

The polyoxymethylene (POM) fiber was melt spun by use of different commercial grades of POM resin, and the effect of post-drawing on mechanical properties and microstructures was investigated extensively. The fiber obtained from the POM resin with a higher melt flow index (MFI) exhibits a better hot-drawing capability and also achieves a greater ultimate draw ratio. The mechanical evaluation reveals that the tensile strength and elastic modulus of POM fiber are improved significantly after post-drawing compared to the as-spun fibers. Although the greater draw ratios result in higher mechanical strength and modulus for the POM fiber, the fiber obtained from the POM resin with an MFI of 13.0 g/10 min achieves the optimal mechanical performance at the ultimate draw ratio. The morphologic and structural developments of POM fiber were studied by scanning electronic microscopy and X-ray powder diffraction. The results indicate that the POM fiber spun by the resin with an MFI of 13.0 g/10 min has a smooth lateral surface and a compact cross section after post-drawing. The fiber samples spun by the POM resins with low MFIs show some hollow disfigurements as well as a rough surface at the ultimate draw ratio, whereas the fiber obtained from the resin with a high MFI of 27.0 g/10 min presents the ununiformity of diameter after post-drawing. The POM fibers achieve a crystalline orientation during the hot-drawing process, which results in a transformation from the spherulitic crystals to the lamellar structure in the drawing direction. The level of crystalline orientation can be improved with an increase of draw ratio and thus results in a high modulus and strength for the resulting POM fiber samples. In addition, the thermal analysis indicates that the crystallinity of the as-spun fibers can be enhanced by post-drawing due to the orientation-induced crystallization.     

Weibull distribution analysis of the tensile strength of the kenaf bast fiber

This paper presents the influence of the gage length on the kenaf fiber Young’s modulus and the tensile strength characterization. Four different gage lengths of 10 mm, 15 mm, 20 mm and 25.4 mm are selected in this study and the tensile testing is performed at a quasi-static loading rate of 1 mm/min. The cross-sectional area of the fiber after failure is considered for the stress calculations. Weibull probability distribution is used to characterize the tensile strength of the kenaf fiber. The Weibull parameters are obtained for the two parameter, three parameter and Weibull of Weibull models and the average tensile strength of the fibers are evaluated. The predicted average tensile strength from all the three approaches are in good agreement with the experimental results for the obtained parameters.     

Investigation of inter fiber cohesion in yarns. I. Influence of certain spinning parameters on the cohesion in cotton yarns

This paper investigates the influence of raw material and process parameters in spinning that affect the inter fiber cohesion in yarns. An instrument has been developed for measuring the minimum twist of cohesion. With regard to the raw material parameters, the influence of different cotton fiber mixings for a given count of yarn is investigated. Also the effect of spinning to varying counts for a given cotton variety is studied. With regard to the process parameters, studies have been carried out to investigate the influence of noil extraction in comber, number of draw frame passages, draft pressure in ring frame and direction of twist. Cohesion improved with increase in the noil extraction percentage in the comber. Increase in the number of draw frame passages also improved the cohesion. Draft pressure in ring frame improved the fiber cohesion in yarn up to a pressure of 2.1 kg/cm². Direction of twist had no effect on the cohesion.     

Relationship between fiber orientation distribution function and mechanical anisotropy of thermally point-bonded nonwovens

Current efforts to establish links between geometrical features and mechanical performance of nonwoven fabrics in general, and of point-bonded (spot-bonded) nonwovens in particular has been made using the measurements of Fiber Orientation Distribution Function (ODF) and tensile modulus which occurs during controlled-deformation experiments. Image analysis technique (using the Fast Fourier Transform) was used to quantify the fiber orientation distribution. The results suggest that, within a typical window of processing conditions, the fiber orientation has a significant influence on the anisotropical behavior of nonwoven. The data also suggest that mechanical anisotropy of thermally point-bonded nonwovens is likely to be governed by different load transfer mechanism according to the applied macroscopic tensile direction.     

Experimental study and prediction of the diameter of melt-electrospinning polypropylene fiber

Firstly, the effects of the spinning temperature, spinning voltage, tip-to-collector distance and ambient temperature on the diameter of melt-electrospinning polypropylene (PP) fibers were studied. The results showed that with the increase of the spinning temperature, spinning voltage and tip-to-collector distance, the fiber diameters first decreased and then increased. However, when the ambient temperature increased, the fiber diameters increased gradually. Secondly, based on the previous results, the response surface methodology (RSM) was used to investigate the combined effects of processing parameters on fiber diameters and establish a second-order polynomial equation to predict the fiber diameter. The results showed that the effect order of four factors on fiber diameter was as follows: spinning temperature > tip-to-collector distance > ambient temperature > spinning voltage. Moreover, the fiber diameter predicted by response surface analysis fitted well with the experimental result. Finally, three layer melt-electrospinning PP webs with different fiber diameters were online compounded with conventional non     

An experimental study of influence of filament and roving location on yarn properties during embeddable and locatable spinning

This study was focus on the influence of filament and roving location on yarn properties during embeddable and locatable spinning (ELS). ELS composite yarns were produced with various filament and roving locations on an experimental ring spinning frame. Besides yarn formation zone configurations, ELS yarn properties were compared including yarn hairiness, unevenness and tensile properties. Results showed that spinning triangles became larger; however, the reinforced composite spinning strand length kept constant. With a constant filament-roving spacing on each side of ELS, Filament spacing variations caused no significant changes of spun yarn hairiness, tenacities, imperfections and unevenness CV. For roving location variations with constant filament spacing, the reinforced strand length became longer as the roving spacing increased. Hairs exceeding 3 mm were lower for ELS yarn spun with 4 mm and 10 mm roving spacings than that spun with 6 mm, 8 mm and 12 mm roving spacings. Roving spacing variations had a trivial influence on ELS yarn unevenness; whereas, yarn tensile index variation coefficients fluctuated dramatically due to hairiness variations for different roving spacings.     

The analysis of the influence of fiber length distribution on the theoretical and additional unevenness of yarn

Fiber length distribution has an impact not only on the theoretical unevenness of yarn caused by random fiber alignment, but also upon the additional unevenness caused during processing, especially in drafting. For a given fiber length distribution, there is a discrepancy between the theoretical unevenness of yarn which is calculated with Martindale’s equation and the actual unevenness tested by instrument. In order to reflect the effect of fiber length distribution on the theoretical unevenness of yarn, in this research, a kernel function was used to estimate the probability density function of fiber length, therefore, calculation of Suh’s model for theoretical unevenness was realized. On this basis, the theoretical and additional unevenness of yarn were calculated. The statistical influence of fiber length parameters on yarn unevenness was discussed. It can be concluded that decreasing the values of effective length, length irregularity and 16 mm SFC by weight would improve the uniformity of yarn.