Polyamide Fibers Research Articles

Determination of thermal expansion coefficient of a monofilament polyamide fiber using digital image correlation

Coiled polymer actuators are a type of artificial muscles that are a promising development in the field of smart materials. The coefficient of thermal expansion of monofilament polyamide fibers is a crucial parameter for understanding the actuation of coiled fibers. The main purpose of this work is to develop a new methodology for estimating the coefficient of thermal expansion and the transition temperature of monofilament polymer fibers. In the experimental procedure, axial deformations of monofilament polyamide fiber samples were induced by temperature variations using a controlled thermal system. These deformations were determined from images of polyamide samples using the digital image correlation method. Two different approaches based on distinct temperature conditions were conducted. An alternative model with three parameters, including the coefficient of thermal expansion, was introduced to describe the thermal-mechanical behavior of monofilament polyamide fibers. Moreover, polyamide samples were also characterized using four conventional methodologies. Results indicated that the coefficient of thermal expansion changed of a modest negative value to a large negative value and this transition occurred around the glass transition temperature of the polyamide. The thermal expansion curves demonstrate good repeatability and all estimated parameters were in accordance with literature, indicating that the proposed approach can be suitable for the proposed study. This investigation may help in understanding of the intrinsic thermal-mechanical behavior of polymeric monofilaments employed as actuators.

Processing of waste carbon and polyamide fibers for high-performance thermoplastic composites: Modifications to the auto-leveling system to enhance the quality of hybrid drawn sliver

The auto-leveling system of a modern draw frame is widely used for conventional fibers to develop homogeneous, uniform, and defect free drawn slivers. This auto-leveling system also improves the quality of tapes and hybrid yarn structures by eliminating mass irregularities in hybrid sliver. However, the existing auto-leveling system exerts very high loads on feedstock, thus diminishing the quality of waste carbon in the delivered sliver. The aim of the present study was to process hybrid sliver based on waste carbon and polyamide fibers on a modern draw frame and modify the auto-leveling system to enable the damage-free processing of carbon fiber. For this purpose, hybrid card slivers were processed on an industrial draw frame with auto-leveling system. The different auto-leveling parameters, e.g., scan roller width and scan roller load, were modified and optimized for the uniform and damage-free processing of hybrid sliver. Results revealed that the scan roller load has a significant influence on the quality of waste carbon fiber in hybrid sliver. A uniform hybrid sliver ensures the reproducibility of unidirectional tapes and hybrid yarn at industrial scale, while simultaneously maintaining the quality of recycled carbon fiber-reinforced thermoplastics.

Обоснование правил подобия разрывной нагрузки рыболовных крученых изделий

The article focuses on the problem of physical modeling of the physical and mechanical properties of fishing twisted filamentary materials, in particular, the most important one – the breaking load. The problems arise because of conducting full-scale experiments, particularly when the ropes of large diameter are used to build the rope parts of fishing gear. The solution to the problem of determining the breaking load on filamentary parts can be found by using specialized tensile testing machines and modern software, which is an effective tool for predicting the reliability and a resource of a gear part operating in difficult conditions of dynamic and shock loads. However, de-signing of fishing gear must begin with large-scale modeling, which will help to correctly calculate the physical and mechanical properties of the designed object using the well-known parameters of the full-scale material. The similarity rules of breaking load of fishing twisted filamentary gear used for the construction of industrial fishing tools will make it possible to model new elements of these tools without conducting full-scale experiments. At the same time, they will already contain solutions to problems associated with studying the dynamic processes, deformation, fracture, as well as the prediction of reliability and resource of the material. The technique proposed based on determining the scale of similarity of filamentary gear made of polyamide fibers, will help to simu-late various net and rope elements from filaments gear of various sizes and structures, instead of conducting energy-intensive experimental studies on ropes of large diameter.

The effects of pulverization treatment for the mechanical properties of polyamide 6 fiber filled with carbon nanotubes

An advanced and latest method for pulverizing the aggregates of carbon nanotubes (CNTs) by wet-jet milling process has been adopted for reinforcement of polyamide 6 (PA6) fibers. Unpulverized and pulverized CNTs were added to PA6 fibers by using general type kneading and spinning apparatus. Although the tensile modulus of PA6 fibers 6% increased by adding CNTs, regardless of the pulverization treatment, the tensile strength 10% increased only by adding pulverized CNTs. The improvements in the mechanical properties were attributed to the mechanical properties of CNTs themselves because CNTs have little effect on the crystallization and interaction with polymer chains of PA6. On the other hand, the aggregates were observed in PA6 fibers with unpulverized CNTs while CNTs were highly dispersed in PA6 fibers with pulverized CNTs. Therefore, it is revealed that the pulverization of CNTs is a significant factor for improving tensile strength of PA6 fibers. Applying pulverization technique to PA6 fibers aids a feasibility of wide range of applications such as tennis racket strings.

Hydrophilic and antibacterial surface functionalization of polyamide fabric by coating with polylysine biomolecule

Polyamide (PA) fiber is the second largest synthetic fiber, and extensively applied in underwear, outerwear, sports/leisure wear and decorative fabrics. However, PA textiles have poor wearing comfort resulting from their inherent hydrophobicity, and do not possess antibacterial function which is vital for preventing bacterial infections. To address these issues, this study employed polylysine (PLL) biomolecule to fabricate the hydrophilic and antibacterial surface on PA fabric by a dip coating technique. The Schiff base reaction between the aldehyde groups of glutaraldehyde and the amino groups of PLL and PA fiber was utilized to increase washing resistance. The effects of the dip coating conditions of PLL on the hydrophilicity of PA fabric were studied by the wetting time of water droplet. The hydrophilicity imparted to PA fabric by PLL coating was further confirmed by water contact angle, moisture adsorption and capillary effect tests. The PLL coated fabric exhibited excellent hydrophilic and antibacterial properties with good washing durability. The functional surface of the PLL coated fabric was proved by scanning electron microscope, X-ray photoelectron spectroscopy, and charge effect. The present research suggests that PLL biomolecule can be used as a surface coating agent for simultaneously imparting hydrophilic and antibacterial functions to PA fiber.

Азосоединения на основе 2-(4'-аминофенил)-4-хинолинкарбоновой кислоты: синтез и свойства

Synthesis and studies of the properties of dyes for coloring textile materials from fibers of various chemical structures, which contain, in addition to chromophore, also pharmacophore groups in the molecule, which impart biocidal properties to both the dyes themselves and the materials dyed by them, are interesting both theoretically and from an applied point of view. The article presents data on the synthesis of a series of previously undescribed azo compounds based on 2-(4'-aminophenyl)-4-quinolinecarboxylic acid and aromatic hydroxy- and aminocompounds of the naphthalene series. Five naphthylazo derivatives of 2-(4'-aminophenyl)-4-quinolinecarboxylic acid were synthesized in high yields. The structures of the synthesized azo compounds were confirmed by mass-spectrometry and UV-spectroscopy. In the electronic absorption spectra, the absorption maximum of the synthesized azo compounds lies in the range of 480-550 nm, in contrast to the initial diazo and azo components, the absorption maxima of which lie in the near UV region of the spectrum. Dyeing techniques have been developed that provide optimal indicators for the process of coloration of polypeptide fibers (wool and nylon) with synthesized dyes. The colors of the samples have bright, and deep colors of orange-red-violet scales. The obtained painted samples were examined for color fastness to wet processing according to GOST 9733.4-83, sweat GOST 9733.6-83 and light exposure GOST 11279.2-83. It has been shown that the synthesized azo compounds can be used for coloring woolen and polyamide fibers and provide satisfactory performance properties of dyes, which is consistent with generally accepted ideas about acid dyes. Samples of dyed polyamide fabric showed satisfactory color fastness to light (1-3 points), the best result was shown by wool samples dyed with the studied dyes.

Synthesis and application of urethane-containing azo disperse dyes on polyamide fabrics

A series of new azo disperse dyes containing the urethane group were synthesized through the reaction between the hydroxyl group in coupling component of disperse dyes and p-toluene isocyanate. The structures of the new dyes were fully confirmed by 1H NMR, 13C NMR, FT-IR, MS and Elemental analysis. Their characteristics for the visible-light absorption and color fastness on polyamide fibers were respectively measured and compared with those of the original dye. It was found that the new dyes exhibited hypsochromic effect, and had the nearly unchanged absorption half band and higher molar extinction coefficients, the fastness properties has been greatly improved, especially for the washing and sublimation fastness. The new dyes 2d and 2e containing double urethane groups possessed excellent fastness properties on polyamide fabrics. These two dyes for all the fastness tested, including water fastness, sublimation fastness, rubbing fastness and light fastness, had reached 4–5 and 5 rates. It was very clear that the introduction of urethane group and the increase of molecular weight can effectively improve the fastness of disperse dyes for the polyamide fibers.

From hybrid fibers to microfibers: The characteristics of polyamide 6/polypropylene blend via one‐step twin‐screw melt extrusion

Multimaterial textiles are frequently employed to attain a certain function or aesthetic effect. The multimaterial assemblies face recycling limitations due to challenges to sort and separate the component materials. A one‐step melt extrusion approach to process two mixed common textile polymers, polyamide 6 (PA6), and polypropylene (PP), into PA6:PP hybrid fibers is reported in this study. PA6:PP hybrid fibers were produced in four different configurations; PA6‐50 (50 wt% PA6), PA6‐60 (60 wt% PA6), PA6‐65 (65 wt% PA6), and PA6‐80 (80 wt% PA6). The PP component was sacrificially removed from the hybrid fibers and the resultant PA6 fiber structure was analyzed. The SEM images show the development of PA6 microfibers in PA6‐50 and PA6‐60 hybrid fibers with mean diameters of 0.76 μm and 1.13 μm upon fiber drawing, respectively. In PA6‐65 hybrid fibers, the PA6 microfibers were found along with areas where PA6 was encapsulating the PP. Thermal and mechanical properties of the untreated and treated hybrid fibers were also investigated. PA6‐60 hybrid fibers were processed into single jersey knitted fabrics and treated to obtain PA6 microfibers fabrics. The bursting strength and wicking properties of the fabric, before and after treatment, were comparatively studied. POLYM. ENG. SCI., 60:690–699, 2020. © 2020 Society of Plastics Engineers

Sound absorption, thermal, and flame retardant properties of nonwoven wall cloth with waste fibers

In order to solve the recycling problem of waste fibers, the nonwoven wall cloth was prepared with waste wool fibers and low-melting-point polyamide fibers as raw materials by combing into a net and hot-pressing method. The effect of fiber length, hot pressing temperature, mass fraction of the waste wool fibers, volume density, thickness of materials, and thickness of the rear air layer on the sound absorption properties were studied by single factor experiments. Under the optimized technological conditions, the sound absorption coefficient was above 0.91 and the noise reduction coefficient was 0.56. Then, the sound absorption mechanism was analyzed. In order to meet the fire resistance requirements of materials in the construction industry, by the orthogonal experiments, range analysis, and variance analysis, the optimal process conditions were as follows: potassium fluotitanate concentration of 8%, treatment time of 40 min, and treatment temperature of 80°C. The limit oxygen index of the nonwoven wall cloth was 32.5%. The nonwoven wall cloth had good sound absorption and flame retardant properties.

Effect of toughened polyamide/carbon fiber interlace braid fabric on the mechanical performance of CFRP laminates

Delamination resistance and epoxy matrix brittle fracture have been the main issues in carbon/epoxy composites laminates. Various studies have been reported to complement the brittle fracture of epoxy matrix. Conventional methods of fabricating toughened carbon/epoxy composite laminates were thermo-plastic veils and films interleaving methods, directly toughening the matrix resin and dispersing nanoparticles in the matrix. In this study, the carbon/epoxy composites laminates were manufactured using carbon fiber/polyamide fiber braided fabrics. The chemical interactions between polyamide and epoxy matrix resin were investigated by Fourier transform infrared spectroscopy, which resulted in ring opening of the epoxide group by the amide group. The compression after impact strength and the interlaminar toughness of the carbon/epoxy composite laminate were increased by 31%, and the strain energy release rates were increased by 120% compared to the virgin interface composite. In the case of carbon/epoxy composite laminates interlaced with polyamide fibers, the mechanical properties, such as the tensile strength and fatigue properties, were improved as tensile modulus decreased.

Appraisal on Varied Natural and Artificial Fiber Reinforced Polymeric Composites

Abstract Professionals, experts and scientists of modern era treasure the use of Fiber-reinforced Polymer Composites and find these very significant due to the necessity in countless arenas like automobiles, infrastructure, marine vessels and equipment, chemical industry, sporting goods, domestic articles etc. These mixtures of amalgams of strengthened fibers also develop extensively as possible fixings for the construction of composites of diverse applications. These inventions are not only used as an alternative reinforcement due to their high level of specific strength but also hail with the rewards of low price, less heaviness and adequate good mechanical possessions or properties. Here, experts must take note of the lavish obtainability of natural and synthetic elements in India like kenaf, jute, oil palm, cotton flax, hemp, sisal, nylon, polyester, etc. These elements are the boundless gift of the nature and acquiring thorough attention in every nook and corner of today’s technology. These crossbred complex materials are undoubtedly a combination of more than one dissimilar kinds of filament which are armored in a single chemical compound or contrariwise and display inimitable possessions that are challenging to attain from a single sort of hybrid complex materials of strengthened fiber polyamide. Complex chemical compounds or polyamides do demonstrate an important and remarkable function of congeniality over filaments besides the heftiness of cross complex materials. Therefore the assortment of polymer with fibers should be always considered cautiously

Polymeric fiber reinforced concrete exposed to fire

The aim of this work was to investigate the influence of the addition of polypropylene, polyester, polyamide, aramid and aramid pulp fibers on the behavior of concretes subjected to high temperatures. For that, test specimens with fiber additions were made at a rate of 2 kg/m3 and submitted to temperatures in furnace, as well as to high temperatures through direct fire test. Columns were also built and subjected to a live fire simulator belonging to the Espírito Santo Fire Department - Brazil. Microstructural and mechanical properties were analyzed. It has been observed that the fibers may influence the properties of the concrete and that fire tests with standard fire load may be an alternative or complementary analysis of concrete subjected to elevated temperatures.

A New Approach to Produce Eco-friendly Antibacterial and Antistatic Polyamide Yarns

In this paper, we reported on environmental technique of developing for the deposition of silver nanoparticles onto polyamide (PA) fibers. A new composite PA yarn with carboxyl methyl starch (CMS) including silver nanoparticles (AgNPs) has been synthesized. The influence of silver nitrate concentration on the morphological and spectrophometeric properties was investigated. SEM images showed the distribution of silver nanoparticles and nanolayer formation on the surface. Electrical conductivity of composite yarns was measured by four point probe technique and was changed from 1.574x10-7 to 2.630x10-4 S/cm. The antibacterial activities of the composite yarns have been investigated against Escherichia coli and determined considerable antibacterial properties.

Processing of waste carbon and polyamide fibres for high-performance thermoplastic composites: influence of carding parameters on fibre orientation, fibre length and sliver cohesion force

The processing of waste carbon fibre on carding machine for the developments of nonwovens, tapes and hybrid yarn structures is an emerging trend. These structures are widely used to enhance the performance efficiency of recycled carbon fibre reinforced thermoplastic composites. The aim of the research presented in this study is to process waste carbon fibre on a carding machine and to investigate the influence of different carding parameters on waste carbon fibre. For this purpose, card slivers composed of waste carbon and polyamide fibres were developed on a double cylinder card machine by varying technical parameters. Then, effect of these parameters on card sliver quality was assessed in terms of fibre orientation, fibre length and sliver cohesion force. Results revealed that fibre orientation and fibre length is significantly affected by technological parameters carding zones, whereas the sliver cohesion force is significantly affected by the speed of feed roller and doffer.

Fractography combined with unsupervised pattern recognition of acoustic emission signals for a better understanding of crack propagation in adhesively bonded wood

In this paper, acoustic emission (AE) signals obtained during quasi-static crack propagation in adhesively bonded beech wood were classified using an unsupervised pattern recognition method. Two ductile one-component polyurethane (1C-PUR) adhesives with the same formulation except for one system being reinforced with short polyamide (~ 1 mm long) fibers were compared to a relative brittle phenol–resorcinol–formaldehyde (PRF) adhesive. Using only localized AE signals, it was shown that the signals originating from the crack propagation could be classified into two different clusters. Comparing the AE signals with a new fractography method, it was estimated that different clusters are due to distinct failure mechanisms, with signals of cluster 1 being associated with wood failure and signals of cluster 2 with adhesive failure. The obtained results suggest that for the PRF adhesive the wood fibers help to slow down the crack propagation. A similar but lesser effect was noted for the polyamide fibers added to the 1C-PUR adhesive matrix.

Investigation of the Mechanical and Electrical Properties of Elastic Textile/Polymer Composites for Stretchable Electronics at Quasi-Static or Cyclic Mechanical Loads.

In the last decade, interest in stretchable electronic systems that can be bent or shaped three-dimensionally has increased. The application of these systems is that they differentiate between two states and derive there from the requirements for the materials used: once formed, but static or permanently flexible. For this purpose, new materials that exceed the limited mechanical properties of thin metal layers as the typical printed circuit board conductor materials have recently gained the interest of research. In this work, novel electrically conductive textiles were used as conductor materials for stretchable circuit boards. Three different fabrics (woven, knitted and nonwoven) made of silver-plated polyamide fibers were investigated for their mechanical and electrical behavior under quasi-static and cyclic mechanical loads with simultaneous monitoring of the electrical resistance. Thereto, the electrically conductive textiles were embedded into a thermoplastic polyurethane dielectric matrix and structured by laser cutting into stretchable conductors. Based on the characterization of the mechanical and electrical material behavior, a life expectancy was derived. The results are compared with previously investigated stretchable circuit boards based on thermoplastic elastomer and meander-shaped conductor tracks made of copper foils. The microstructural changes in the material caused by the applied mechanical loads were analyzed and are discussed in detail to provide a deep understanding of failure mechanisms.

KINETIC AND STRUCTURAL CHARACTERISTICS OF ULTRAFILTRATIONAL MEMBRANES AT SEPARATION OF SOLUTIONS CONTAINING SODIUM LAURYLSULPHATE

In work the generalized analysis of literary data on a research of relative permeability ratio of various types of porous organic and inorganic membranes was submitted. Application of a method of X-ray analysis of samples of the semipermeable ultrafiltrational membranes on a diffractometer of DRON-3 and a specific output flow on a flat-chamber ultrafiltration unit is shown. In materials of work the pilot and theoretical studies on isokinetic zones and structural characteristics of polymeric semipermeable membranes in the course of ultrafiltrational separation of the technological solutions containing the anionic and fissile surface substances are conducted. It is experimentally confirmed that kinetic curves on a specific output flow have two isokinetic zones. The first zone, the stage of the ultrafiltration process, proceeds quickly, lasts only a few minutes - 7.8 min and 13.05 min, the second zone is slower with duration of about 30 min and 60 min for ultrafiltration cellulose acetate membranes of the UAM-100 and UAM-50 series, respectively. The revealed isokinetic zones differ in characteristic times, which differ by orders of magnitude, and, as a result, the final kinetic dependence has an exponential form. The comparative analysis of roentgenograms allows to note coincidence of angles of diffraction, but significant redistribution of intensity of reflexes in air-dried and working sapless in the range of scattering angles 2θ from 8°-35°. The obtained experimental data and their comparison with literary, indicate the same set of the diffraction reflexes at corners 2θ = 17°; 22°; 25° for both samples of membranes that corresponds to the crystal reflexes of membranes created from polyamide fibers (nylon).

Effect of Calcium Chloride on Dyeing Property of Polyamide 66 Based on Reactive Anthraquinone Dyes with Different Structure

The effect of calcium chloride on dyeing property of polyamide 66 based on reactive anthraquinone dyes with different structures were investigated. The relationship of the structure and properties of the reactive anthraquinone dyes was discussed. Calcium chloride could obviously improve the exhaustion and fixation of the reactive dyes on polyamide 66. The dyes with more sulfonate groups exhibited obviously sensitive to calcium chloride. Compared with the traditional dyeing method, three reactive anthraquinone dyes achieved better building up property and color yields by using calcium chloride at pH value of 7.0. Calcium chloride had obvious dyeing acceleration for polyamide 66. The anthraquinone dye with bifunctional groups could achieve higher exhaustion and excellent fastness on polyamide 66. The mechanism of calcium chloride to exert an influence on dyeing property of polyamide 66 was analyzed. This work is of great significance for improving dyeing performance of reactive dyes on polyamide fiber.

Surface activation of polyamide fibers by radio-frequency capacitive plasma for application of functional coatings

The results of experimental researches on the modification of polyamide fibrous materials for technical purposes by low-pressure radio-frequency capacitive discharge plasma are presented. The effect of plasma modification on the wettability of polyamide fibers and their adhesive properties was studied.

DOĞAL VE SENTETİK LİF ESASLI KOMPAKT İPLİKLERDEN ÜRETİLEN GÖMLEKLİK KUMAŞLARIN BAZI MEKANİK VE HAVA GEÇİRGENLİĞİ ÖZELLİKLERİNİN İNCELENMESİ

Shirting fabrics are one of the most demanded product groups for textile consumers. Although cotton is the most preferred fibre as the raw material of shirting fabrics, fibres such as Polyester, Elastane, viscose and their blends with cotton may also be utilized in the shirting fabrics. For the convenience usage of shirting fabrics in apparel products, those fabrics’ durability and air permeability properties should be considered in detail. Fabric constructional parameters such as weave structure, warp and weft yarn density, yarn count, fibre type are the main influential factors on shirting fabrics’ mechanical and air permeability properties. This study has been performed in order to evaluate the effect of fabric construction on some mechanical properties such as tear strength, seam strength, crease recovery angle (°) as well as on air permeability of the shirting fabrics. Throughout the study, plain, dobby and satin shirting woven fabrics were produced from the compact yarns with several combinations of cotton, linen, polyamide, viscose and elastane fibre blends. Pre-treated samples were objected to tear strength test, seam strength test, crease recovery angle (°) test and finally to air permeability test. Randomized One –Way ANOVA test was performed in order to investigate the significant effect of fabric type on some mechanical and air permeability properties of shirting fabrics at significance level of 0.05. Test results were statistically evaluated and it was generally observed that there was a significant effect of fabric type on tear strength, seam strength, crease recovery angle and on air permeability features of the shirting fabrics at significant level of 0.05.