Identification of the Process of Dynamic Stretching of Threads in Warp Knitting Technology Part II: Experimental Identification of the Process of Stretching Threads, with Verification of Rheological Models

Prążyńska, Aleksandra / Mikołajczyk, Zbigniew

Published Online: 2018-03-20 | DOI: https://doi.org/10.1515/aut-2017-0016

The study is a continuation of the first part of the publication, concerning the theoretical analysis of sensitivity of rheological models of dynamically stretched thread. This part presents the experimental research on the characteristics of stretching forces as a function of time, in the context of comparing the obtained results with theoretical data.

The selected research material was three types of polyester silk threads with linear densities 84, 110 and 334 dtex. During the tests, threads of 400 to 1300 mm were stretched at speeds in the range of V ∈ [0.65, 1.47] m/s, which corresponds to the knitting speed n ∈ [700, 1600] courses/min. An original measuring device for empirical identification of dynamic processes of threads stretching was used during the tests. In total, 36 tests variants were performed. The procedures of mathematical equivalence were also worked out for the rheological models of Kelvin-Voigt, Zener and the three-parameter Standard model 2, which enabled the description of threads stretching phenomena in technological processes with the help of generalized rheological model, taking into account the visco-elastic qualities of threads.

Experimental results showed that for the assumed deformation speeds ε(t) ∈ [0.53, 4.00] 1/s, the open three-parameter models – Standard model 2 and Zener model most reliably describe the stretching process.

Keywords: rheological models; dynamic stretching of threads; knitting on warp-knitting machines; empirical verification of rheological model

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Date Added: 2018-03-22

Effect of Filament Fineness on Composite Yarn Residual Torque

 Sarıoğlu, Esin / Babaarslan, Osman / Avcı, Münevver Ertek

Published Online: 2018-03-20 | DOI: https://doi.org/10.1515/aut-2016-0036

Yarn residual torque or twist liveliness occurs when the twist is imparted to spin the fibers during yarn formation. It causes yarn snarling, which is an undesirable property and can lead the problems for further processes such as weaving and knitting. It affects the spirality of knitted fabrics and skewness of woven fabrics. Generally, yarn residual torque depends on yarn twist, yarn linear density, and fiber properties used. Composite yarns are widely produced to exploit two yarns with different properties such on optimum way at the same time and these yarns can be produced by wrapping sheath fibers around filament core fiber with a certain twist. In this study, the effect of filament fineness used as core component of composite yarn on residual torque was analyzed. Thus, the false twist textured polyester filament yarns with different filament fineness were used to produce composite yarns with different yarn count. The variance analysis was performed to determine the significance of twist liveliness of filament yarns and yarn count on yarn twist liveliness. Results showed that there is a statistically significant differences at significance level of α=0.05 between filament fineness and yarn residual torque of composite yarns.

Keywords: microfilament; composite yarn; yarn residual torque

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Date Added: 2018-03-22

Thermal and Flame Retardant Properties of Shaped Polypropylene Fibers Containing Modified-Thai Bentonite

Prahsarn, Chureerat / Roungpaisan, Nanjaporn / Klinsukhon, Wattana / Suwannamek, Natthaphop / Padee, Sirada

 


Published Online: 2018-03-20 | DOI: https://doi.org/10.1515/aut-2016-0040

Tetraphenyl phosphonium-modified organoclay (TPP-Mt) was prepared by modifying montmorillonite-rich Thai bentonite via ion exchange. TGA results revealed that TPP-Mt possessed high thermal stability, where degradation occurred at a temperature range of 418-576°C. The obtained TPP-Mt/PP nanocomposites exhibited degradation at higher temperatures than PP (410-420°C vs. 403°C). Fibers of different cross-sectional shapes (circular, circular hollow, and cross) containing 1, 2 and 3%wt TPP-Mt were prepared and characterized. Nonwovens of 3%wt TPPMt/PP fibers were fabricated for flame retardant test. From results, nonwovens of TPP-Mt/PP fibers exhibited self-extinguishing characteristic and the areas of burning were less than that of PP nonwoven (14.5-31.6% vs. 95.6%). Nonwovens of cross-shaped fibers showed the best flame retardant property, followed by those of circular hollow and circular fibers. The flame retardant properties observed in nonwovens were explained due to the inter-fiber spaces between cross-shaped fibers and center hole in circular hollow fibers, which could trap initiating radicals inside, thus reducing flame propagation. In addition, large surface area in cross-shaped fibers could help in increasing the flame retardant effectiveness due to more exposure of TPP-Mt particles to the flame. Knowledge obtained in this study offered an approach to produce flame retardant nonwovens via a combination of modified organolcay and fiber shape.

Keywords: Modified organoclay; Flame retardant; Shaped fibers; Nonwovens

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Date Added: 2018-03-22

Thermal Absorptivity Model of Knitted Rib Fabric and its Experimental Verification

Mangat, Asif Elahi / Hes, Lubos / Bajzik, Vladimir / Mazari, Adnan

Published Online: 2018-03-20 | DOI: https://doi.org/10.1515/aut-2017-0003

Thermal absorptivity is an indicator of warm and cool feeling of textile materials. An equation based on thermal absorptivity of polyester in solid form, porosity of a fabric, and relative contact area of human skin and fabric surface has been developed to characterize thermal absorptivity of fabric. For verification of suggested model, 15 knitted rib fabrics were produced using 100% polyester yarn and having different surface profile. ALAMBETA semiautomatic non-destructive instrument has been used for measuring the effective thermal absorptivity of knitted rib fabric. It was found that the suggested simple theoretical model exhibits significant agreement with the measured thermal absorptivity values of knitted rib fabric, which endorsed the approach applied.

Keywords: Thermal absorptivity; rib knit fabric; contact area; porosity

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Date Added: 2018-03-22

Effect of Air Gap Entrapped in Firefighter Protective Clothing on Thermal Resistance and Evaporative Resistance

He, Hualing / Yu, Zhicai

Published Online: 2018-03-20 | DOI: https://doi.org/10.1515/aut-2017-0006

Heat and water vapor transfer behavior of thermal protective clothing is greatly influenced by the air gap entrapped in multilayer fabric system. In this study, a sweating hot plate method was used to investigate the effect of air gap position and size on thermal resistance and evaporative resistance of firefighter clothing under a range of ambient temperature and humidity. Results indicated that the presence of air gap in multilayer fabric system decreased heat and water vapor transfer abilities under normal wear. Moreover, the air gap position slightly influenced the thermal and evaporative performances of the firefighter clothing. In this study, the multilayer fabric system obtained the highest thermal resistance, when the air space was located at position B. Furthermore, the effect of ambient temperature on heat and water vapor transfer properties of the multilayer fabric system was also investigated in the presence of a specific air gap. It was indicated that ambient temperature did not influence the evaporative resistance of thermal protective clothing. A thermographic image was used to test the surface temperature of multilayer fabric system when an air gap was incorporated. These results suggested that a certain air gap entrapped in thermal protective clothing system could affect wear comfort.

Keywords: Multilayer fabric system; thermal insulation; thermo-physiological comfort; air gap; sweating guarded hotplate

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Date Added: 2018-03-22

Visual-Simulation-Based Personalized Garment Block Design Method for Physically Disabled People with Scoliosis (PDPS)

Hong, Yan / Bruniaux, Pascal / Zeng, Xianyi / Liu, Kaixuan / Curteza, Antonela / Chen, Yan

Published Online: 2018-03-20 | DOI: https://doi.org/10.1515/aut-2017-0001

This research presented a novel method using 3D simulation methods to design customized garments for physically disabled people with scoliosis (PDPS). The proposed method is based on the virtual human model created from 3D scanning, permitting to simulate the consumer’s morphological shape with atypical physical deformations. Next, customized 2D and 3D virtual garment prototyping tools will be used to create products through interactions. The proposed 3D garment design method is based on the concept of knowledge-based design, using the design knowledge and process already applied to normal body shapes successfully. The characters of the PDPS and the relationship between human body and garment are considered in the prototyping process. As a visualized collaborative design process, the communication between designer and consumer is ensured, permitting to adapt the finished product to disabled people afflicted with severe scoliosis.

Keywords: Virtual simulation; disabled people; atypical morphotype; knowledge engineering; 3D design; ergonomics

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Date Added: 2018-03-26

Tensile Damage Mechanism of 3-D Angle-Interlock Woven Composite using Acoustic Emission Events Monitoring

Ma, Qian / Wang, Ke / Wang, Shu-Dong / Liu, Hua / Jin, Bo-Cheng / Jin, Li-Min / Ma, Pibo

Published Online: 2018-03-20 | DOI: https://doi.org/10.1515/aut-2017-0010

The quasi-static tensile damage behavior of one type of layer-to-layer 3-Dimensional Angle-interlock Woven Composite (3DAWC) was tested and analyzed in this paper. Incorporated with the acoustic emission (AE) events monitoring, the mechanical behavior of the 3DAWC under tensile loading condition was characterized. The Load-Extension curve, Load/AE events-Time curves occurred during the entire testing process and tensile damage modes were recorded to characterize and summarize the mechanical properties and damage mechanism of the 3DAWC subjected to tensile loading. It was found that the tensile damage of the 3DAWC could be summarized into 3 steps. And each step has a distinct primary damage mode. Moreover, the resin cracks, resin-yarn interface debonding and yarn breakages were the main damage modes for the 3DAWC.

Keywords: 3-D Angle-interlock Woven Composite (3DAWC); Quasi-static tension; Acoustic Emission (AE); Damage mechanism

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Date Added: 2018-03-22

Analysis and Comparison of Thickness and Bending Measurements from Fabric Touch Tester (FTT) and Standard Methods

Musa, Atiyyah Binti Haji / Malengier, Benny / Vasile, Simona / Van Langenhove, Lieva / De Raeve, Alexandra

Published Online: 2018-03-20 | DOI: https://doi.org/10.1515/aut-2017-0011

Fabric Touch Tester (FTT) is a relatively new device from SDL Atlas to determine touch properties of fabrics. It simultaneously measures 13 touch-related fabric physical properties in four modules that include bending and thickness measurements. This study aims to comparatively analyze the thickness and bending measurements made by the FTT and the common standard methods used in the textile industry. The results obtained with the FTT for 11 different fabrics were compared with that of standard methods. Despite the different measurement principle, a good correlation was found between the two methods used for the assessment of thickness and bending. As FTT is a new tool for textile comfort measurement and no standard yet exists, these findings are essential to determine the reliability of the measurements and how they relate to the well-established standard methods.

Keywords: fabric touch tester; thickness; bending; standard method

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Date Added: 2018-03-22

Optimization of Operational Parameters of Foam Sizing Process for Cotton Yarns Based on Plackett-Burman Experiment Design

Zhu, Bo / Liu, Jianli / Gao, Weidong

Published Online: 2018-03-20 | DOI: https://doi.org/10.1515/aut-2017-0009

This study was aimed at investigating the process optimization of foam sizing for cotton yarns. In this work, effects of major foam-sizing process factors including size concentration, blowing ratio, stirring speed, pre-wetting temperature, pre-drying temperature, squeezing pressure and drying temperature were studied on the hairiness (more than 3 mm) and abrasion resistance of foam-sized yarns. The combination of Plackett-Burman, steepest ascent path analysis and Box-Behnken design were adopted to optimize the foam-sizing process of cotton yarns. Results revealed that size concentration, blowing ratio and squeezing pressure were significant factors that affected the hairiness and abrasion resistance. Optimum hairiness and abrasion resistance were obtained when the cotton yarns were sized at size concentration of 19.33%, blowing ratio of 4.27 and squeezing pressure of 0.78kN. The theoretical values and the observed values were in reasonably good agreement and the deviation was less than 1%. Verifcation and repeated trial results showed that it has good reproducibility and imparts the foam sizing process of cotton yarns.

Keywords: Foam sizing; cotton yarns; Plackett-Burman design; Box-Behnken design; process optimization

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Date Added: 2018-03-22

Enhanced Photocatalytic Properties of Ag-Loaded N-Doped Tio2 Nanotube Arrays

Gao, Dawei / Lu, Zhenqian / Wang, Chunxia / Li, Weiwei / Dong, Pengyu

Published Online: 2018-03-20 | DOI: https://doi.org/10.1515/aut-2017-0005

Highly ordered TiO2 nanotube (TiO2 NT) arrays were prepared by anodic oxidizing method on the surface of the Ti substrate. Nitrogen-doped TiO2 nanotube (N-TiO2 NT) arrays were carried out by ammonia solution immersion, and Ag nanoparticles loaded N-doped TiO2 nanotube (Ag/N-TiO2 NT) arrays were obtained by successive ionic layer adsorption and reaction (SILAR) technique. The samples were characterized by the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL) emission spectra, ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy (DRS). The result indicated that the diameter and wall thickness of the TiO2 NT are 100–120 and 20–30 nm, respectively. Moreover, the morphology and structure of the highly ordered TiO2 NTs were not affected by N-doping. Furthermore, Ag nanoparticles were evenly deposited on the surface of TiO2 NTs in the form of elemental silver. Finally, the photocatalytic activity of Ag/N-TiO2 NTs was evaluated by degradation of methyl orange (MO) under visible-light irradiation. The Ag/N-TiO2 NTs exhibited enhanced photocatalytic properties, which could reach 95% after 90-min irradiation.

Keywords: N-doped TiO2 NTs; Ag nanoparticle; visible light; photocatalysis

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Date Added: 2018-03-25

An Investigation into Dynamic Puncture Resistance of the Polyester Needled Nonwoven Geotextiles using Video Processing Technique

Dehghan-Banadaki, Zahra / Mashroteh, Hasan / Ahmadi, Mohammad Saleh

Published Online: 2018-03-20 | DOI: https://doi.org/10.1515/aut-2017-0012

In this study, the dynamic puncture behavior of nonwoven needle-punched polyester geotextiles has been studied using video processing technique. Twenty-seven needle-punched geotextile samples were produced by changing areal weight, needle penetration depth and punch density as independent variables. Cone drop test was carried out on the samples. In addition to measuring the hole diameter (HD), the video processing technique with a high frame rate camera was employed to calculate the energy absorbed by geotextile fabric up to puncture point (Ep) and the hole expansion energy (Ee). Multiple linear regression method was used to develop the predicting relationships between independent and reply variables. The models showed that an increase in areal weight results in an increase in Ep, whereas it causes a decrease in Ee and HD. Moreover, increasing punch density and needle penetration depth, leads to less Ep, and more Ee and HD. In addition, it was also found that significant relationships exist for Ep-HD and Ee-HD.

Keywords: Geotextile; needle-punched nonwoven; dynamic puncture resistance; cone drop test; video processing

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Date Added: 2018-03-25

Prediction of Electric Permittivity of Threads in Woven Fabric

Leśnikowski, Jacek

Published Online: 2018-03-20 | DOI: https://doi.org/10.1515/aut-2017-0031

In the article, a new method for the estimation of electric permittivity of threads (filaments) was presented. The proposed recursive method is based on the results of computer simulation of 3D model of transmission stripline. This model contains a model of flat fabric having threads, with which electric permittivity should be determined. The described procedure uses the method proposed by Barry to obtain permittivity of flat fabric from the so-called s parameters of the simulated stripline. In the proposed method, the permittivity of the flat fabric obtained from simulation is compared with the measured value of permittivity of real flat fabric in order to estimate the threads’ permittivity. This comparison is needed to obtain the electric permittivity of threads forming this fabric. The article also presents examples of the obtained values of threads’ permittivity and discussion about the accuracy of the method. The presented method will be useful in situations where the knowledge of permittivity of threads is necessary in the conducted research.

Keywords: threads electric permittivity; woven properties; dielectric properties of textiles; filaments permittivity

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Date Added: 2018-03-25
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