Bicomponent Fibers Research Articles

Poling and characterization of piezoelectric polymer fibers for use in textile sensors

This study reports on the poling and characteristics of a melt-spun piezoelectric bicomponent fiber with poly(vinylidene fluoride) (PVDF) as its sheath component and a conductive composite with carbon black (CB) and high density polyethylene (HDPE) as its core component. The influence of poling conditions on the piezoelectric properties of the fibers has been investigated. The poling parameters temperature, time and poling voltage have been varied and the piezoelectric effect of both contact- and corona-poled yarns have been evaluated. The results show that a high piezoelectric effect is achieved when the poling voltage is high as possible and the poling temperature is between 60°C and 120°C. It was also shown that permanent polarization is achieved in a time as short as 2s in corona-poled fibers. A yarn exposed to a sinusoidal axial tension of 0.07% strain (the corresponding force amplitude was 0.05N) shows an intrinsic voltage output of 4V. The mean power from a 25mm length of yarn is estimated to be 15nW. To demonstrate the fibers sensor properties, they are woven into a textile fabric from which a force sensor is manufactured and used to detect the heartbeat of a human.

Numerical analysis of dynamic out-of-plane loading of nonwovens

This paper presents finite element (FE) modelling of deformation behaviour of thermally bonded bicomponent fibre nonwovens under out-of-plane dynamic loading. Nonwoven fabric was treated as an assembly of two regions with distinct mechanical properties. Bond points were treated as composite material having a matrix of the sheath material reinforced with fibres of the core material. Elastic-plastic and viscous properties of the constituent fibres, obtained with tensile and relaxation tests were implemented into the FE model. The mechanical behaviour of the material under out-of-plane dynamic loading was observed with visual techniques. The deformation behaviour of nonwoven under out-of-plane dynamic loading computed with the numerical model was compared with that observed in the tests.

Spinnability and Characteristics of Polyvinylidene Fluoride (PVDF)-based Bicomponent Fibers with a Carbon Nanotube (CNT) Modified Polypropylene Core for Piezoelectric Applications.

This research explains the melt spinning of bicomponent fibers, consisting of a conductive polypropylene (PP) core and a piezoelectric sheath (polyvinylidene fluoride). Previously analyzed piezoelectric capabilities of polyvinylidene fluoride (PVDF) are to be exploited in sensor filaments. The PP compound contains a 10 wt % carbon nanotubes (CNTs) and 2 wt % sodium stearate (NaSt). The sodium stearate is added to lower the viscosity of the melt. The compound constitutes the fiber core that is conductive due to a percolation CNT network. The PVDF sheath’s piezoelectric effect is based on the formation of an all-trans conformation β phase, caused by draw-winding of the fibers. The core and sheath materials, as well as the bicomponent fibers, are characterized through different analytical methods. These include wide-angle X-ray diffraction (WAXD) to analyze crucial parameters for the development of a crystalline β phase. The distribution of CNTs in the polymer matrix, which affects the conductivity of the core, was investigated by transmission electron microscopy (TEM). Thermal characterization is carried out by conventional differential scanning calorimetry (DSC). Optical microscopy is used to determine the fibers’ diameter regularity (core and sheath). The materials’ viscosity is determined by rheometry. Eventually, an LCR tester is used to determine the core’s specific resistance.

Modeling of the Mechanical Properties of a Wood-Fiber/Bicomponent-Fiber Composite

An engineered composite that combines a wood fiber core, a bicomponent fiber face, and a bicomponent fiber back was evaluated for its elastic response using laminate theory. Using the properties of the individual laminae as input variables, the laminate’s elastic modulus, axial strain, and lateral strain were determined by means of the model, and compared with values determined experimentally. The model yielded an axial elastic modulus of 950 MPa, which did not differ substantially from the measured value of 920 MPa. Statistical analyses showed that the measured and calculated strains were not significantly different in either the axial or lateral directions. The model underpredicted the strains along the fiber direction of the bicomponent fiber sheets by approximately 4%. A greater difference (12%) between predicted and measured values was observed in the lateral direction.

The Effect of Processing Parameters Onpoly (Lactic Acid)/Poly(Ethylene Oxide)Bicomponentultrafine Fibersby Co-Electrospinning

Poly (lactic acid) (PLA)/polyethylene oxide (PEO) bicomponent fibers werefabricated by co-electrospinning technique in a side by side configuration. Effect of PEO concentration, PLA and PEO solution flow rate and an applied voltage on formation, size and morphology of the fibers were investigated. The results showed that the fibers size increased with increasing PEO concentration, PEO flow rate ratio and applied voltage. The composition of the fibers was confirmed by IR spectrum. Additionally, by pairing PEO, which is a water soluble polymer, with PLA, follow by PEO phase removal in water, a C-shaped ultrafine fiber was prepared.

Effects of binder fibers and bonding processes on PET hollow fiber nonwovens for automotive cushion materials

In this study, nonwoven fabrics were developed for the replacement of polyurethane foams in car interiors, in particular, cushioning materials for car seats. Polyethylene terephthalate (PET) hollow fibers and two types of bicomponent binder fibers were used to manufacture automotive nonwovens by carding processes and then post-bonding processes, such as needle punching or thermal bonding. The physical and mechanical properties of nonwovens were thoroughly investigated with respect to the effects of binder fibers and bonding processes. The tensile strength and elongation for nonwovens were found to be significantly improved by combined needle punching and thermal bonding processes. In addition, the nonwoven cushioning materials were characterized in terms of hardness, support factors, and compressive and ball rebound resilience. The nonwovens showed greater hardness than the flexible PU foam. However, support factors over 2.8 for the nonwovens indicated improved seating comfort, along with better seating characteristics of greater resilience and air permeability in comparison with the PU foam.

The Research of Splitting Craft for Air Filter with Sea-Island Superfine Fiber Needled Fabrics

Although the bag-type dust collector is dust capture equipment which is low cost and high efficiency, it has less filter efficiency to ultra fine particles for its of thicker fiber. So ultrafine fiber were used by bicomponent fiber with splitting craft to improve the filtration efficiency of ultra fine particles greatly. A piece of polyester/nylon sea-island superfine fiber needled nonwovens were splitted processing for nine times by the orthogonal design. And fibre microscopic photographs, weight loss rate and strength were analyzed. The best choice of splitting craft as followed: lye concentration is 16%, splitting time 15 min and splitting temperature is 95 °C.

Modified Crystallization in PET/PPS Bicomponent Fibers Revealed by Small-Angle and Wide-Angle X-ray Scattering

We present a small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) characterization of the semicrystalline structure of homo- and heterobicomponent core–sheath fibers melt-spun from poly(ethylene terephthalate) (PET) and poly(phenylene sulfide) (PPS). The two-dimensional SAXS/WAXS patterns of the various bicomponent fibers are found to reflect the mutual influence of the components on their thermal profiles along the spinline, leading to modified crystallization of the PET component and a larger strain rate in the PPS component. The predominant scattering features in the SAXS patterns are four-point reflections, an intense equatorial streak, and a central anisotropic diffuse scattering. The four-point reflections are attributed to tilted crystalline lamellar stacks of PET. The lamellar stack dimensions and the orientation of their lamellar surfaces are determined. We find that the heterobicomponent arrangement can promote the formation of equally spaced and uniformly sized crystallites in the PET phase and highly oriented crystallites in the PPS phase.

Configuring the spinning technology of PTT/PET bicomponent filaments according to fabric elasticity

This paper studied the configuration of spinning technology of PTT (polytrimethylene terephthalate)/PET (polyethylene terephthalate) bicomponent fiber via measurements obtained from the elasticity testing of fabrics made of them. The effects of four main spinning parameters on the elasticity of two series, named Z and Q, of interwoven fabrics were explained, including different ways of binding, intrinsic viscosity differences, and the percentage contents of PTT and the temperature of the hot plate. The experimental results indicated that the elongation ratios of the fabrics, which were made of PTT/PET bicomponent filaments spun by the parallel bound method, with larger differences in the intrinsic viscosity of the two ingredients and a higher temperature of the hot plate, were much larger than that of its corresponding counterparts. The elastic modulus ratio (m) and the PTT contents exhibited a cross-impact on crimp curves of PTT/PET bicomponent filament fabrics. The elongation ratios of fabrics made of PTT/PET bicomponent filaments would augment effectively as the hot plate temperature increased within a temperature range under the same posttreatment.

Preparation of bicomponent fibers by surface modification with fibrous carbon nanostructure filler

Surface treatment of carbon PAN fibers was performed by growing carbon nanostructures using chemical vapor deposition and a mixture of benzene and cyclohexane at 800°C. Fibrous samples with deposited catalyst and with the initial surface were characterized by scanning electron microscopy, Raman scattering, and x-ray phase analysis. Furthermore, the micromechanical characteristics of a model composite monofilament—epoxide matrix were studied using fiber fragmentation. It was found that the resistance to interphase shear for a composite reinforced by surface-treated fiber increased 2.3 times compared with untreated fiber.

Self-crimped bicomponent fibers containing polypropylene/ethylene octene copolymer

Melt spinning of side-by-side bicomponent fibers, containing ethylene octene copolymer (EOC) and polypropylene (PP) was conducted to investigate effects of composition ratios and fiber draw ratios on fiber crimp characteristics. The obtained EOC/PP bicomponent fibers exhibited self-crimping with different degree of crimpness when were fully stretched. Fiber crimpness tended to increase with increasing EOC content (up to 50%), but decreased with fiber draw ratio. Fibers of 50/50 EOC/PP ratio possessed highest fiber crimpness with regard to crimp length and extensibility. Self-crimping behavior was explained to yield from imbalance force, as a result of difference in elasticity and orientation, between EOC and PP phases.

Design and Characterization of a Bicomponent Melt‐Spun Fiber Optimized for Artificial Turf Applications

AbstractArtificial turf is robust, playable in all weathers and has a long service life. Polyamide (PA) flooring has excellent resilience but provokes abrasion injuries (friction burn); polyethylene (PE) monofilaments are skin‐friendly but tend to permanent deformation. To maximize resilience while minimizing the risk of skin abrasion, PA‐PE bicomponent fibers are developed. Numeric simulation is applied to find optimized fiber cross‐sections and material combinations, accompanied by melt‐spinning of respective filaments and validation of the model. The resulting artificial grass resembles natural turf with respect to playability and appearance and does not need any granular infill. magnified image

Directed inorganic modification of bi-component polymer fibers by selective vapor reaction and atomic layer deposition

Nanocomposite organic/inorganic materials with spatially-controlled composition can be formed using vapor-phase atomic layer deposition (ALD) on bi-component polymer fibers. The ALD process promotes selective precursor infusion into the inner core of a core/shell polymer fiber, yielding nanoparticles encapsulated within the core. Likewise, choosing alternate precursors or reaction conditions yield particles or films on the outer polymer shell. In-situ infrared spectroscopy and transmission electron microscopy show that infusion yields selective dispersion of aluminum oxide in different polymer regions, forming fine nanoparticle dispersions or films. Selective inclusion of metal oxide materials during atomic layer deposition on polymers can create unique organic/inorganic composite structures for many advanced uses.

Mechanical characterisics of needle-punched materials treated with heated air

A study is made of the relationship between the deformation and strength characteristics of needle-punched materials made from a mix of polyester and bicomponent fibers and treated with heated air. This type of treatment is very effective for obtaining materials with good initial tensile strength. However, the material’s resistance to deformation is preserved with relatively little elongation. Its strength increases only in the transverse direction.

Influence of polymer type, composition, and interface on the structural and mechanical properties of core/sheath type bicomponent nonwoven fibers

In this study, we investigated the effect of polymer type, composition, and interface on the structural and mechanical properties of core–sheath type bicomponent nonwoven fibers. These fibers were produced using poly(ethylene terephthalate)/polyethylene (PET/PE), polyamide 6/polyethylene (PA6/PE), polyamide 6/polypropylene (PA6/PP), polypropylene/polyethylene (PP/PE) polymer configurations at varying compositions. The crystallinity, crystalline structure, and thermal behavior of each component in bicomponent fibers were studied and compared with their homocomponent counterparts. We found that the fiber structure of the core component was enhanced in PET/PE, PA6/PE, and PA6/PP whereas that of the sheath component was degraded in all polymer combinations compared to corresponding single component fibers. The degrees of these changes were also shown to be composition dependent. These results were attributed to the mutual interaction between two components and its effect on the thermal and stress histories experienced by polymers during bicomponent fiber spinning. For the interface study, the polymer–polymer compatibility and the interfacial adhesion for the laminates of corresponding polymeric films were determined. It was shown that PP/PE was the most compatible polymer pairing with the highest interfacial adhesion value. On the other hand, PET/PE was found to be the most incompatible polymer pairings followed by PA6/PP and PA6/PE. Accordingly, the tensile strength values of the bicomponent fibers deviated from the theoretically estimated values depending on core–sheath compatibility. Thus, while PP/PE yielded a higher tensile strength value than estimated, other polymer combinations showed lower values in accordance with their degree of incompatibility and interfacial adhesion. These results unveiled the direct relation between interface and tensile response of the bicomponent fiber.

Piezoelectric polymeric bicomponent fibers produced by melt spinning

AbstractMelt spinning of a novel piezoelectric bicomponent fiber, with poly(vinylidene fluoride) as the electroactive sheath component, has been demonstrated. An electrically conductive compound of carbon black (CB) and high density polyethylene was used as core material, working as an inner electrode. A force sensor consisting of a number of fibers embedded in a soft CB/polyolefin elastomer matrix was manufactured for characterization. The fibers showed a clear piezoelectric effect, with a voltage output (peak‐to‐peak) of up to 40 mV under lateral compression. This continuous all‐polymer piezoelectric fiber introduces new possibilities toward minimal single fiber sensors as well as large area sensors produced in standard industrial weaving machines. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Pore structure and liquid behavior of nonwovens composed of nanosized fibers by conjugate spinning

AbstractNonwovens composed of nanofibers are of interest for use in high‐function textile materials, such as filtration, insulation, and absorption media. The pore structure of nonwovens has a dominant influence on the performance characteristics of the final products, particularly in controlling the transport properties. The transport properties include the filtration of gas and liquid, sound absorption, and heat transfer. In this study, we focused on the pore structure and liquid behavior of needle‐punched nonwovens composed of nanofibers produced by conjugate spinning. Nanofiber nonwovens were prepared with poly(ethylene terephthalate)/co‐(polyethylene terephthalate) sea‐island bicomponent fibers by an alkali treatment. The pore diameter distributions were experimentally obtained with a capillary flow porosimeter; this indicated that the nonwovens composed of nanofibers had a compact and uniform textile structure. Moreover, a comparison of the pore diameters, water absorption, and wicking behaviors of the nonwovens before and after the alkali treatment was made. The nonwovens composed of nanofibers possessed excellent water absorption capacities and fast wicking behaviors. Thus, they have promising potential applications as absorption media. In addition, a theoretical model of air volume and channel radius for liquid behavior was established and compared with the experimental results. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Structural factors and physical properties of needle-punched nonwovens based on Co-PET/PA bicomponent fibers via alkali treatment

Needle-punched nonwovens are widely used in industrial fields. However, they are limited to some applications such as high-efficiency filters, high-performance synthetic leathers, and high-absorption wipes because of their low surface area and large pore size. In this study, needle-punched nonwovens composed of Copolyethylene terephthalate (Co-PET)/Polyamide (PA) sea-island bicomponent fibers were treated in NaOH solution with various conditions for preparing nonwovens composed of ultra-fine fibers. The effect of NaOH concentration and treatment temperature on the structural factors and physical properties of nonwovens was investigated. The morphological structures of Co-PET and PA components were analyzed by scanning electron microscope. After alkali treatment, fiber diameter was significantly reduced from 23.65 to 3.95 μm, specific surface area of nonwovens increased more than five times, calculated and experimental mean pore diameter decreased by 83.6 % and 20.8 %, respectively. By increasing NaOH concentration and treatment temperature, pore diameter was reduced, thereby decreasing the air permeability of nonwovens. Meanwhile, tensile strength increased and tearing strength decreased as NaOH concentration and treatment temperature were increased in both machine and cross direction, respectively. The treatment temperature of alkali treatment was significantly influenced by the physical properties of nonwovens.

Effect of benzyl triethylammonium chloride on microstructure of bicomponent polymeric fibers during electrospinning

AbstractEffect of benzyl triethylammonium chloride (BTEAC) on the microstructure of electrospun bicomponent fibers, i.e., polyvinylidene fluoride (PVDF)/polycarbonate (PC), polyacrylonitrile (PAN)/polyethylene glycol (PEG), and PAN/PVDF, was investigated in this article. The evolution of morphology and microstructure of the above bicomponent fibers were examined by scanning electron microscopy, transmission electron microscopy, and X‐ray photoelectron spectroscopy. The results showed that distinct core/shell structured fibers were successfully prepared from PVDF/PC and PAN/PVDF via introducing a small amount of BTEAC, whereas only cocontinuous structure was detected in the electrospun PAN/PEG fibers. This study could be an example of electrospun multipolymer dispersions influencing by an organic salt, and it could be extended to control the structure of carbon nanofibers via electrospinning. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

Composite Nonwovens

The term ‘composite nonwovens’ refers to a category of materials different from ‘nonwoven composites’, which consist of a resinous matrix reinforced by an embedded nonwoven fabric. Many scientists would like to rename ‘composite nonwovens’ as ‘soft nonwoven composites’ and ‘nonwoven composites’ as ‘hard nonwoven composites’. Composite nonwovens are created by a modern and innovative industry employing nonwoven technologies to bring together fibres of different origins, different characteristics or a combination thereof. Combination of different nonwoven preforms prepared either by employing a variety of process technologies or by combining nonwoven preforms with traditional textile preforms into a consolidated structure can also result in the creation of composite nonwovens. Composite nonwovens can provide an engineered solution by creating multifunctional products as well as an economical solution by eliminating manufacturing processes and replacing two or more products by a single product. Business activity in the field of composite nonwovens is therefore expected to grow substantially. In this paper, recent research into composition, manufacture, structure–property relationships and applications of composite nonwovens is reviewed beginning with an overview of composite nonwovens encompassing definitions, types, scope and business-related aspects. It then proceeds to discuss the characteristics of both natural and man-made fibres along with some speciality fibres such as bicomponent fibres and micro- and nanofibres in the development of composite nonwovens before exploring manufacturing processes used in creating composite nonwovens. The underlying nonwoven preparation methods and composite processes, such as multi-forming and multi-bonding, together with other more unusual composite processes are described before exploring structure–property relationship in composite nonwovens, including multicomponent nonwovens, multilayered nonwovens, hybrid nonwovens and nonwovens containing particulates or active ingredients. Applications of composite nonwovens in diverse products ranging from wound dressings, surgical gowns, facemasks to absorbent wipes and respirator filters are described. Finally, the review highlights the future prospects for composite nonwoven materials.