Drawing Of Filaments Research Articles

Printable and filament-drawable PDMS based adhesive assisted manufacturing of highly conductive copper micro-patterns

Manufacturing of copper micro-patterns is crucial in electronics for its utilization as high conductivity transparent conductive films (TCFs) and circuits. In the preparation process of current TCFs, a plethora of materials have emerged that can replace traditional indium tin oxide (ITO). However, even for the most promising metal-based nanowire materials, there are issues such as high cost, complex welding, and high contact resistance. To address these problems, this paper proposes a printable and filament-drawable polydimethylsiloxane (PDMS)-based adhesive, which, through a novel additive patterning technology, efficiently and economically manufactures self-welding copper micro-meshes and circuits. The adhesive can be processed into micro-patterns through printing and filament drawing, on which ionic Ag can be in situ reduced and anchored, thereby eliminating the need for tedious pre- and post-treatment steps. The fully exposed Ag particles dramatically minimize the usage of precious metal catalyst, thus efficiently catalyzing electroless copper deposition (ECD) reaction. Highly conductive (1.03 × 107 S m−1) copper circuits can be fabricated on the printed adhesive patterns, exhibiting versatile applicability to diverse substrates. Highly precise copper micro-meshes (∼50 μm) can be fabricated on the filament networks drawn by the adhesive. The copper meshes undergo complete self-welding at junctions during the ECD process, thus exhibiting ultra-low square resistance of 0.45 Ω sq−1 while maintaining a high transmittance of 82.2 %. This is far superior to most of TCFs in published literature.

High-Performance PEEK/MWCNT Nanocomposites: Combining Enhanced Electrical Conductivity and Nanotube Dispersion.

High-performance engineering thermoplastics offer lightweight and excellent mechanical performance in a wide temperature range. Their composites with carbon nanotubes are expected to enhance mechanical performance, while providing thermal and electrical conductivity. These are interesting attributes that may endow additional functionalities to the nanocomposites. The present work investigates the optimal conditions to prepare polyether ether ketone (PEEK)/multi-walled carbon nanotube (MWCNT) nanocomposites, minimizing the MWCNT agglomerate size while maximizing the nanocomposite electrical conductivity. The aim is to achieve PEEK/MWCNT nanocomposites that are suitable for melt-spinning of electrically conductive multifilament's. Nanocomposites were prepared with compositions ranging from 0.5 to 7 wt.% MWCNT, showing an electrical percolation threshold between 1 and 2 wt.% MWCNT (107-102 S/cm) and a rheological percolation in the same range (1 to 2 wt.% MWCNT), confirming the formation of an MWCNT network in the nanocomposite. Considering the large drop in electrical conductivity typically observed during melt-spinning and the drawing of filaments, the composition PEEK/5 wt.% MWCNT was selected for further investigation. The effect of the melt extrusion parameters, namely screw speed, temperature, and throughput, was studied by evaluating the morphology of MWCNT agglomerates, the nanocomposite rheology, and electrical properties. It was observed that the combination of the higher values of screw speed and temperature profile leads to the smaller number of MWCNT agglomerates with smaller size, albeit at a slightly lower electrical conductivity. Generally, all processing conditions tested yielded nanocomposites with electrical conductivity in the range of 0.50-0.85 S/cm. The nanocomposite processed at higher temperature and screw speed presented the lowest value of elastic modulus, perhaps owing to higher matrix degradation and lower connectivity between the agglomerates. From all the process parameters studied, the screw speed was identified to have the higher impact on nanocomposite properties.

Improving mechanical properties of melt‐spun polyetherimide monofilaments by thermal drawing

AbstractSuper engineering plastics, such as polyetherimide (PEI), are widely used in various fields owing to their multifunctional properties. PEI is used in automobiles, electronics, and medicine owing to its high thermal resistance, excellent mechanical strength, flame retardancy, and chemical resistance. In this study, melt‐spun PEI filaments were thermally drawn and the effect of the drawing process conditions on their mechanical properties was investigated. To understand the mechanical properties of various forms, such as films, sheets, granules, tubes, and rods of PEI postprocessing, it is based on analyzing the behavior in one‐dimensional structures. The mechanical properties of the PEI filaments were dictated by the draw ratio, process temperature, and cooling temperature of the thermal drawing process. In addition, maintaining the drawing process temperature around the glass transition temperature (220°C) of PEI elongated the filament by up to 80%. Furthermore, the optimized cooling temperature was 150°C and draw ratio was 50%. In conclusion, PEI filaments with excellent mechanical properties were obtained by optimizing the draw ratio, process temperature, and cooling temperature of thermal drawing. Through the behavior of the molecular and crystal structures by thermal drawing of PEI filament, it is expected to be applied to two‐ or three‐dimensional structures.

Fabrication of High-Performance CNT Reinforced Polymer Composite for Additive Manufacturing by Phase Inversion Technique.

Additive Manufacturing (AM) of polymer composites has enabled the fabrication of highly customized parts with notably mechanical properties, thermal and electrical conductivity compared to un-reinforced polymers. Employing the reinforcements was a key factor in improving the properties of polymers after being 3D printed. However, almost all the existing 3D printing methods could make the most of disparate fiber reinforcement techniques, the fused filament fabrication (FFF) method is reviewed in this study to better understand its flexibility to employ for the proposed novel method. Carbon nanotubes (CNTs) as a desirable reinforcement have a great potential to improve the mechanical, thermal, and electrical properties of 3D printed polymers. Several functionalization approaches for the preparation of CNT reinforced composites are discussed in this study. However, due to the non-uniform distribution and direction of reinforcements, the properties of the resulted specimen do not change as theoretically expected. Based on the phase inversion method, this paper proposes a novel technique to produce CNT-reinforced filaments to simultaneously increase the mechanical, thermal, and electrical properties. A homogeneous CNT dispersion in a dilute polymer solution is first obtained by sonication techniques. Then, the CNT/polymer filaments with the desired CNT content can be obtained by extracting the polymer’s solvent. Furthermore, optimizing the filament draw ratio can result in a reasonable CNT orientation along the filament stretching direction.

Hybrid Filaments from Saccaharina lattisima Biomass: Engineering of Alginate Properties with Maleic Anhydride Grafted Linseed Oil.

Linseed oil was graft modified with maleic anhydride and introduced into alginate by co-extrusion, producing alginate hybrid filaments. A straightforward grafting of maleic anhydride onto the oil backbone produced the modified oil. Additional esterification with n-dodecanol was also investigated. The structures of the modified oils were verified with 2D-NMR. The modified oil was mixed with alginate and extruded into CaCl2, forming thin filaments with diameters in the 130–260 μm range. The impact of oil integration into the alginate filaments was assessed, with special emphasis on stress-at-break, and compared to values predicted by an empirical model relating the “stress to alginate concentration” ratio to prevailing conditions during filament drawing. Analogous alginate filaments were prepared with hydrochloric-, oxalic- and phytic acid calcium salts for comparison with alginate–oil hybrids to reveal the induced impact, with respect to the composition and charge, on the tensile performance.

Adaptive wire diameter control of the high-precision optical fibre drawing machine

Different from the conventional methods such as the Proportional-Integral-Derivative (PID)-based method, an adaptive control algorithm (ACA) is proposed in this paper to control the wire diameter of high-precision fibre drawing machines (FDMs). A simple FDM model is established to acquire the relationship between fibre diameter and drawing velocity before the ACA is introduced. The comparison simulation of the accuracy of fibre diameter between the proposed ACA and traditional PID is made, and the ACA is applied to actual fibre drawing processes, so as to validate the ACA. The comparative results show that the fluctuation of filament diameter is smaller and the accuracy is higher under the ACA control. In actual fibre filament drawing processes, the ACA can limit the diameter error within ±2μm, which meets the production requirements.

Conductive hybrid filaments of carbon nanotubes, chitin nanocrystals and cellulose nanofibers formed by interfacial nanoparticle complexation

In this paper, anionic TEMPO-oxidized cellulose nanofibers (TO-CNFs) and cationic, partially deacetylated, chitin nanocrystals (ChNCs) were used to fabricate continuous composite filaments (TO-CNF/ChNC filament) with a straightforward and sustainable aqueous process based on the interfacial nanoparticle complexation (INC) of oppositely charged nano-constituents. In particular, the role of TO-CNF and ChNC concentrations in filament drawing and the effect of drawing speed on the mechanical properties of composite filaments were investigated. Moreover, conductive filaments were fabricated by mixing single walled carbon nanotubes (SWCNTs) with TO-CNF dispersion and further complexing with the ChNC aqueous suspension. A conductive filament with an electrical conductivity of 2056 S/m was obtained. However, the increase in the SWCNTs content reduced the mechanical properties of the formed filament compared to neat TO-CNF/ChNC filament. This study not only introduces a new nanoparticle candidate to prepare filaments based on INC method but also provides potential advanced and alternative green filament to be used as wearable electronics in biomedical area.

Continuous drawing of poly(ethylene terephthalate) in ethanol and agile functionalization through infusion

To explore the possibility of applying organic-solvent drawing technique to accomplish a process of industrial significance, continuous drawing of as-spun PET fibers in ethanol was performed. The formation of multiple necks, infusion of ethanol into filament along with the uptake of dissolved dye was observed during the continuous drawing of PET filaments. The propagation speed of individual neck increased as the draw ratio increased, while effect of revolution speed of roller on the neck propagation speed was minimal because of the increase of the number density of neck along with the increase in processing speed. Through the monitoring of the drawing tension, it was found that the fluctuation of drawing tension is a source of instability of the drawing process. The installation of a drawing pin was discovered to be useful for the stabilization of the drawing process while increasing the amount of infused ethanol and dye uptake.

Some aspects of manufacturing prepregs for long-dimensional products from composite materials with a thermoplastic binder

Technology for producing parts from composite materials with a thermoplastic binder differs from traditional manufacturing methods which use thermosetting resins and therefore it requires new design and technological solutions. The approach proposed in this paper involves coating carbon filaments with a layer of thermoplastic melt at the prepreg preparation stage to ensure its more uniform distribution and deeper impregnation at the product molding stage. To describe the rheological properties of a polyether ether ketone melt (PEEK), a generalized Carreau model was applied and its material constants were determined. Based on the finite element method, a numerical model of the process of applying a layer of thermoplastic on a carbon filament in an axisymmetric die was constructed. The velocity, pressure and temperature fields are calculated, and the effect of applied pressure and core drawing speed on the applied layer thickness is determined. The required layer thickness is determined from an equality of the cross-sectional areas of the applied layers and the total area of voids between the filaments and between the carbon fibers. The dependence of the resulting thickness of the applied layer on the filament drawing speed and inlet pressure is determined. Based on the analytical solution of the flat-radial filtration problem, a dimensionless equation is obtained for determining the front of impregnation of a porous carbon fiber under external pressure linearly distributed along the die channel. The proposed mathematical model allows one to determine pressure and temperature fields, kinematics of fluid flow, to evaluate the influence of technological parameters on the thickness of the thermoplastic layer applied on the filament and to predict the degree of homogeneity of the finished product.

High-Performance Filaments from Fractionated Alginate by Polyvalent Cross-Linking: A Theoretical and Practical Approach.

A series of alginate fractions with significant differences in molecular weight and uronic acid compositions were produced by consecutive fractionation and converted to thin and strong cross-linked polymer filaments via extrusion into calcium, aluminum, or polyaluminum (PolyAl) polyvalent solutions followed by drawing and drying. Models were elaborated to relate the alginate uronic acid composition to the tensile performance in both the wet gel filament and the dry filament states. The wet gel model was compared to the theory of the unidirectional elongation of charged polyelectrolyte gels based on the classical rubber elasticity of dilated polymer networks, extended to include the contributions of non-Gaussian chain extensions and the effect of electrostatic interactions. The theory of equilibrium swelling pressure was applied to describe the observed shrinkage of the alginate gels following immersion in a polyvalent solution. Congruent with the theoretical model of charged gels, the tensile performance of the gel filaments prepared from CaCl2 depended on the compositional ratio of guluronic acid dyads in the alginate fraction multiplied by the alginate concentration, while the tensile behavior of wet gel filaments prepared by AlCl3 instead resembled that of elastic solid materials and depended only on the alginate concentration. The dry filament tensile properties were greatly dependent on the preparation conditions, particularly the ratio of stress to alginate concentration and the nature of the ions present during filament drawing. The PolyAl solution effectively caused shrinkage of alginate to a strong extent, and the resulting filaments behaved as highly stiff materials able to withstand stresses of approximately 500 MPa and having elastic moduli as high as 28 GPa.

Dynamic Mechanical Response of Hybrid Physical Covalent Networks − Molecular Dynamics Simulation

SummaryIn this article, we present two principal stimuli that affect the deformation response: additional covalent crosslinking and external deformation. Additional crosslinking leads to hybrid gels which show improved toughness in comparison to the physical gels. The article considers also the change of response of the model as a consequence of external mechanical loading. In this case, the structural changes driven by deformation induce permanent structural changes owing to extensive stretching analogous to filament drawing in spider silk or collagen. Almost identical atomistic configurations are transformed into various materials, depending on the stimulus and the conditions. The intensity of stimuli can be regulated also in real materials. The degree of covalent crosslinking can be regulated for example by ultraviolet irradiation. The permanent changes are observed only when the stretching ratio is sufficiently large and stretching is quick.

Study of optimum spinning parameters for production of T-400/cotton core spun yarn by ring spinning

This article presents the use of quadratic general rotary unitized design method in optimization of spinning parameters of T-400/cotton core spun yarn on a ring frame. T-400 is a bicomponent filament based on sorona 3GT polymer form DuPont. An experimental design was generated using MINITAB© 15 which included three factors and five levels. Three factors were the twist, filament draw ratio, and the spindle speed with respect to the yarn properties tested by Uster tester. The research draws clear application of quadratic general rotary unitized method on optimization, with step by step analysis of the variable factors in relation to responses. The optimum spinning parameters for hairiness, evenness, and tenacity while holding other yarn qualities as limiting factors were the following: twist value 430 TPM, filament draw ratio of 0.945, and the spindle speed of 7494 rpm.

The cytological changes of sperm and oocyte nuclei during fertilization in Phascolosoma esculenta (Sipuncula: Phascolosomatidea)

In this study, we investigated fertilization cytology in Phascolosoma esculenta. The sperm binds to the oocyte envelope in a random position at the point of initial contact. An acrosomal reaction then occurs and the acrosomal filament penetrates the oocyte envelope. The apex of the acrosomal filament contacts with the plasma membrane of the oocyte at the point where the fertilization cone is formed. The fertilization cone then retracts, towing the acrosomal filament back and drawing the sperm into the oocyte. Subsequently, the pores on the oocyte envelope are blocked and filled with fibrin and colloid. After the oocyte is activated by sperm, the first and second meiosis processes start sequentially, followed by the release of the first and second polar bodies. After the second polar body is extruded, the haploid female nucleus rapidly reorganizes to form a female pronucleus. In comparison, the sperm nucleus begins to decondense and dilate after the first polar body is released. The male pronucleus is not formed until the end of the second meiosis. The male and female pronuclei migrate to the centre of the oosperm and are incorporated into the zygote nucleus and then the first cleavage occurs. A two cell embryo is then formed by plasma membrane invagination. The cytological changes of sperm and oocyte nuclei during sperm entry into the oocyte and the fertilization process in P. esculenta are characterized by: (1) the mature oocyte with fertilization ability being in the metaphase of the first meiosis; (2) sperm is drawn into the oocyte by the acrosomal filament and fertilization cone; (3) some abnormal phenomena such as polyspermy, multiple pronuclei and multipolar spindle; and (4) the male pronucleus is formed earlier than the female pronucleus, at which point they will fuse to form a zygote nucleus.

Crystallization of poly(ethylene terephthalate) filaments by infusion of ethanol upon cold drawing

This paper focuses on the infusion behavior and structural development of low oriented amorphous poly(ethylene terephthalate) (PET) filaments drawn at room temperature in ethanol. Along with the transport of ethanol, dyes dissolved in ethanol were infused into the filament during the drawing process. In the early stage of drawing at low draw ratio (DR), multiple neck was observed in the filament containing undrawn and drawn segments of the filament. The color from dyes was observed only in the drawn segments. With further increase of DR the number of necks decreased. Drawing of filament in ethanol required a low drawing stress than the drawing in air and water. Infusion of ethanol into filaments was confirmed by DSC and TGA measurements. Occurrence of crystallization in filaments drawn in ethanol was confirmed by WAXD measurements. Filaments drawn at DR 4 showed distinct equatorial scattering intensity in SAXS pattern. On further increasing in DR the equatorial scattering intensity increased.

Effects of spandex drawing ratio and weave structure on the physical properties of cotton/spandex woven fabrics

In this experimental study, we investigated the effects of spandex filament drawing ratio and weave structures on the properties of cotton/spandex woven fabrics. One-way analysis of variance was used to explore the significant effects of the independent variables on the fabric properties. A regression analysis was also used to derive regression relationships between each of fabric properties and spandex filament drawing ratio. Our findings show that the spandex drawing ratio and structures of the woven fabrics significantly affect the physical and mechanical properties of the cotton/spandex woven fabrics. Cotton woven fabrics containing spandex show higher contraction, crease recovery, and flexural rigidity with increasing spandex drawing ratio, whereas the rest of fabric properties decreases with the increasing drawing ratio. Because of higher contraction and then higher weight, thickness, and cover factor of cotton/spandex fabrics, unexpected results of fabric air permeability and breaking elongation were detected.

Contrasting the Predictions for Coulomb and Creep-Rate-Dependent Friction in the Modeling of Fiber-Draw Processes

One of the most important features in industrial fiber-drawing processes is the friction between filament tow and draw rollers, because it is what creates the tension in the fiber that performs the draw. To understand fiber draw, therefore, it would be valuable to examine the sensitivity of model predictions to the choice of the idealization of the friction incorporated in the model. This paper begins the comparative study by deriving and solving models for fiber draw, which for the first time study the friction between filament tow and draw rollers as something other than Coulomb friction, namely creep-rate-dependent friction. Sensitivity of the draw model to the choice of friction idealization is investigated by contrasting process simulations employing the usual Coulomb model for friction with simulations of the same processes employing the creep-rate-dependent friction model. It is demonstrated that the draw-model predictions of fiber behavior depend both qualitatively and quantitatively on the specific idealization of the friction between filament and rollers. For example, whereas the Coulomb friction model predicts adhesion zones on the rollers, in which the fibers and roller move together with no slip, there are strictly no adhesion zones with the creep-rate-dependent friction model, although with a choice of processing parameters the predicted relative velocity between fiber and roller can be made arbitrarily small. With the creep-rate-dependent friction model the fiber speed at the point of attachment to the draw roller must be greater than the roller surface speed for the equations of momentum to be satisfied. This small, but finite, abrupt change in speed profile can be interpreted as the formation of a neck in the fiber just upstream of the point of attachment to the roller.

Effect of spandex filament draw ratio on elastic core spun yarn properties in friction spinning

The aim of the present study is to produce elastic core/cotton spun yarns in a friction spinning (Dref-II) system and then to investigate the effect of spandex filament draw ratio on the physical and mechanical properties of produced yarns. First, a positive feed device was designed and developed to adjust the spandex draw ratio and then mounted on the friction spinning machine. To maintain a constant yarn count at various draw ratios, the proportion of cotton sheath fibers should be increased. The yarns with larger proportions of cotton fibers showed lower twist. The elastic core spun yarns have lower hairiness in comparison with 100% cotton yarns in the present experiments. The theoretical and experimental results indicate that the tenacity of elastic core spun yarn increases as the spandex draw ratio increases. While the elongation of the elastic core spun yarns is the same as 100% cotton yarn at low spandex draw ratios of less than 3.75, when the spandex draw ratios exceed 3.75, the elongation of the elastic core spun yarn increases sharply.

Processing Effects on the Surface Composition of Glass Fiber

In this study, differences in the surface composition of commercial glass fiber have been characterized as a function of process. The two processes studied were flame attenuation, a high‐temperature combustion‐assisted process, and continuous filament drawing through a bushing. The techniques used to determine the surface compositions were TOF‐SIMS and XPS; the presence of a very thin, boron‐depleted silica‐enriched layer on the flame‐attenuated fibers was most significant. Thermodynamic modeling of the equilibrium vapor pressures at the surface, during fiberization, showed significant differences in the behavior of Na, B, and F species in the two processes. To further test the models, glass fibers were produced under more closely controlled conditions in a laboratory‐scale flame attenuation system. These experiments verified the important effect of flame temperature and residence time in creating the surface layer.

Monofilament drawing device for in situ x-ray scattering studies of orientation development in polymeric fibers

The physical properties of polymer fibers are directly related to the development of orientation in the draw zone under extensional conditions. Although the final properties and microstructure of fibers can be evaluated after processing is completed, it is desirable to understand the development of orientation during drawing independently from the effects superimposed by subsequent unit operations. In situ x-ray scattering measurements of the extrudate in the draw zone provide an ideal means of accomplishing this goal. Depending on the polymeric system to be studied, rotating anode or synchrotron-based x-ray sources may be required, making portability of the fiber drawing device highly desirable. This paper describes an easily transportable in situ x-ray filament drawing device, and discusses typical data obtained using the device to produce filaments from a liquid crystalline nematic solution of poly(cis-benzoxazole) in polyphosphoric acid.

Bacterial Macrofibers and Bionites: Materials of Natural and Synthetic Design

ABSTRACTTwo fiber forms can be obtained from cells of the rod-shaped bacterium,Bacillus subtilis, one called macrofibers, the other bacterial thread. Macrofibers are highly organized, multicellular structures, millimeters in length that selfassemble in a unique way. Each fiber is essentially a single chain of cells linked end-to-end that has repeatedly folded upon itself and twisted into helical form. The growth of individual cells yields both the material of the macrofiber and the forces required for its assembly. The forces involved stem from twisting motions caused by cell growth geometry. The folding process is akin to negative supercoiling. New approaches have been used to estimate the magnitude of forces. Torque generated by single filaments has been estimated from snapopening motions resulting from aborted attempts at folding to be in the range of 10−10to10−8dyne-cm. In contrast, multifilament fibers carrying small wires in their loops must have generated a torque of at least 10−5dyne-cm and a supercoiling force of at least 10−5dyne in order to have moved the wires in viscous solutions at the rates observed. The second bacterial fiber form, bacterial thread, and its mineralized derivatives, called bionites, are man-made materials. They are produced by the drawing and drying of bacterial cell filaments from cultures grown in the form of a textile-like web. The material properties of bacterial thread reflect primarily those of the strength-bearing cell wall polymer, peptidoglycan. A variety of new fiber-like materials have been produced by mineralizing the cell walls in situ in web cultures and drawing the products. Iron, copper, calcium, and potassium phosphate-containing bionites have been obtained in this manner. We are currently searching for order in the bionite crystal forms that may reflect the electrostatic nature of the wall polymer structural templates.