Littérature scientifique sur le sujet « Bicomponent melt spinning »

Sheath-core bicomponent spinning of high molecular weight poly (ethylene terephthalate) (hmpet, IV = 1.02 dl/g) and low molecular weight pet (lmpet, IV = 0.65 dl/g) is done at a take-up velocity range of 1 to 7 km/min. The structures of the individual components in the as-spun bicomponent fibers are characterized. Orientation and orientation-induced crystallization of the hmpet component are enhanced, while those of the lmpet component are suppressed in comparison to corresponding single component spinning. Numerical simulation with the Newtonian model shows that elongational stress in the hmpet component is enhanced and that of the lmpet decreases during high-speed bicomponent spinning. The difference in elongational viscosity is the main factor influencing the mutual interaction between hmpet and lmpet, which in turn affect spinline dynamics, solidification temperature, and structural development in high-speed bicomponent spinning. Simulation with an upper-convected Maxwell model shows that considerable stress relaxation can occur in the lmpet component if the hmpet component solidifies before lmpet. A mechanism for structural development is also proposed, based on the simulation results and structural characterization data.

Upscaling lignin-based precursor fibre production is an essential step in developing bio-based carbon fibre from renewable feedstock. The main challenge in upscaling of lignin fibre production by melt spinning is its melt behaviour and rheological properties, which differ from common synthetic polymers used in melt spinning. Here, a new approach in melt spinning of lignin, using a spin carrier system for producing bicomponent fibres, has been introduced. An ethanol extracted lignin fraction from LignoBoost process of commercial softwood kraft black liquor was used as feedstock. After additional heat treatment, melt spinning was performed in a pilot-scale spinning unit. For the first time, biodegradable polyvinyl alcohol (PVA) was used as a spin carrier to enable the spinning of lignin by improving the required melt strength. PVA-sheath/lignin-core bicomponent fibres were manufactured. Afterwards, PVA was dissolved by washing with water. Pure lignin fibres were stabilized and carbonized, and tensile properties were measured. The measured properties, tensile modulus of 81.1 ± 3.1 GPa and tensile strength of 1039 ± 197 MPa, are higher than the majority of lignin-based carbon fibres reported in the literature. This new approach can significantly improve the melt spinning of lignin and solve problems related to poor spinnability of lignin and results in the production of high-quality lignin-based carbon fibres. This article is part of the theme issue ‘Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 2)’.

Safety workwear often requires antistatic protection to prevent the build-up of static electricity and sparks, which can be extremely dangerous in a working environment. In order to make synthetic antistatic fibers, electrically conducting materials such as carbon black are added to the fiber-forming polymer. This leads to unwanted dark colors in the respective melt-spun fibers. To attenuate the undesired dark color, we looked into various possibilities including the embedding of the conductive element inside a dull side-by-side bicomponent fiber. The bicomponent approach, with an antistatic compound as a minor element, also helped in preventing the severe loss of tenacity often caused by a high additive loading. We could melt-spin a bicomponent fiber with a specific resistance as low as 0.1 Ωm and apply it in a fabric that fulfills the requirements regarding the antistatic properties, luminance and flame retardancy of safety workwear.

A series of polyoxymethylene (POM)/poly(l-lactic acid) (PLLA) blends were prepared by melt extrusion, and their spinnability was confirmed by rheological characterizations, successive self-nucleation, and annealing thermal fractionation analysis. The bicomponent fibers were prepared by means of the melt-spinning and post-drawing technologies using the above-obtained blends, and their morphology, crystalline orientation characteristics, mechanical performance, hydration behavior, and thermal degradation kinetics were studied extensively. The bicomponent fibers exhibited a uniform diameter distribution and compact texture at the ultimate draw ratio. Although the presence of PLLA reduced the crystallinity of the POM domain in the bicomponent fibers, the post-drawing process promoted the crystalline orientation of lamellar folded-chain crystallites due to the stress-induced crystallization effect and enhanced the crystallinity of the POM domain accordingly. As a result, the bicomponent fibers achieved the relatively high tensile strength of 791 MPa. The bicomponent fibers exhibited a partial hydration capability in both acid and alkali media and therefore could meet the requirement for serving as a type of biodegradable fibers. The introduction of PLLA slightly reduced the thermo-oxidative aging property and thermal stability of the bicomponent fibers. Such a combination of two polymers shortened the thermal lifetime of the bicomponent fibers, which could facilitate their natural degradation for ecological and sustainable applications.

In fiber melt spinning, a bunch of polymer melt filaments are continuously drawn and simultaneously cooled with air in order to obtain solidified yarns, which later compose the synthetic fiber in the bobbin. Melt spinning is a basic non-isothermal operation in the production of synthetic fibers, and the velocity and temperature fields in the filaments can be useful to control the quality of the final product. Therefore, the research of the temperature and the speed in the spinning path will be very important. Based on the theory of melt rheology, the co-extrusion morphology and performance of polymer melts PA6 /PET which extrude from circular spinning porous are simulated using finite element method. The effects of the fluid flux ration、cooling air temperature and winding speed on co-extrusion fiber interface and spinning process temperature are analyzed. And the simulated results show that the interfacial offset increases with the increase of the flow rate ratio of two polymers; changing the cooling air temperature, the temperature distribution has the same trend; low winding speed is conducive to the convergence of stretching rate. The simulated results can dynamically and quantitatively reflect the melt flow process, and these results can make guiding sense to engineering application.

The objective of this study is to examine the effect of intumescent flame-retardants (IFR’s) on the spinnability of sheath/core bicomponent melt-spun fibers, produced from Polylactic acid (PLA) single polymer composites, as IFR’s have not been tested in bicomponent fibers so far. Highly crystalline PLA-containing IFR’s was used in the core component, while an amorphous PLA was tested in the sheath component of melt-spun bicomponent fibers. Ammonium polyphosphate and lignin powder were used as acid, and carbon source, respectively, together with PES as a plasticizing agent in the core component of bicomponent fibers. Multifilament fibers, with sheath/core configurations, were produced on a pilot-scale melt spinning machine, and the changes in fibers mechanical properties and crystallinity were recorded in response to varying process parameters. The crystallinity of the bicomponent fibers was studied by differential scanning calorimetry and thermal stabilities were analyzed by thermogravimetric analysis. Thermally bonded, non-woven fabric samples, from as prepared bicomponent fibers, were produced and their fire properties, such as limiting oxygen index and cone calorimetry values were measured. However, the ignitability of fabric samples was tested by a single-flame source test. Cone calorimetry showed a 46% decline in the heat release rate of nonwovens, produced from FR PLA bicomponent fibers, compared to pure PLA nonwovens. This indicated the development of an intumescent char by leaving a residual mass of 34% relative to the initial mass of the sample. It was found that the IFRs can be melt spun into bicomponent fibers by sheath/core configuration, and the enhanced functionality in the fibers can be achieved with suitable mechanical properties.

High thermostability of phase change materials is the critical factor for producing phase change thermoregulated fiber (PCTF) by melt spinning. To achieve the production of PCTF from melt spinning, a composite phase change material with high thermostability was developed, and a sheath-core structure of PCTF was also developed from bicomponent melt spinning. The sheath layer was polyamide 6, and the core layer was made from a composite of polyethylene and paraffin. The PCTF was characterized by scanning electron microscopy (SEM), thermal analysis (TG), Fourier Transform Infra-Red (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and fiber strength tester. The results showed that the core material had a very high thermostability at a volatilization temperature of 235 °C, the PCTF had an endothermic and exothermic process in the temperature range of 20–30 °C, and the maximum latent heat of the PCTF reached 20.11 J/g. The tenacity of the PCTF gradually decreased and then reached a stable state with the increase of temperature from −25 °C to 80 °C. The PCTF had a tenacity of 343.59 MPa at 0 °C, and of 254.63 MPa at 25 °C, which fully meets the application requirements of fiber in textiles.

Abstract Self-crimp side-by-side bicomponent filaments (SBSBFs) were prepared via melt spinning using two kinds of polyethylene terephthalate (PET) with great disparity of intrinsic viscosity. The influence of the volume ratio on the surface morphology, crystallinity, crimping properties, mechanical properties and shrinkage properties of the bicomponent filaments was investigated using wide-angle X-ray diffraction, a differential scanning calorimetry (DSC), scanning electron microscope, etc. As the proportion of the low-viscosity component increases, the shrinkage in boiling water or hot air, as well as the shrinkage force and the sonic orientation factor of the bicomponent filaments decrease, and the DSC heating curves change from double peaks to a single peak. These phenomena should be ascribed to the high orientation and low crystallinity of the high-viscosity PET component and low orientation and high crystallinity of the low-viscosity PET component. Moreover, the crimp property of the bicomponent filament with a volume ratio of 50:50 is superior to those with other volume ratios.

Cette étude s'inscrit dans le cadre du projet européen Interreg entre la Haute de France et la Belgique. Le projet s'appelle Photonitex.L'objectif de ce projet est de développer un textile intelligent de régulation thermique personnelle qui contrôle dynamiquement la température de la peau. Ce travail a été réalisé en collaboration entre le Centre Européen des Textiles Innovants (CETI) et l'Ecole Nationale Supérieure des Arts et Industries Textiles (ENSAIT).L'objectif de cette thèse est de développer une fibre bi-composant pour un textile de confort thermique. La revue de la littérature a été faite pour sélectionner les matériaux polymères les plus appropriés qui sont couramment utilisés dans l'industrie textile. De plus, sur la base de la revue de la littérature, la conception des fibres trilobées bicomposantes a été finalisée pour réaliser le textile de confort thermique dynamique. De plus, les matériaux polymères utilisés doivent présenter une différence hydrophile pour obtenir les propriétés thermiques dynamiques des tissus. Le matériau intérieur de cette fibre trilobée bicomposant doit être plus hydrophile que le matériau extérieur. PA6 et PA6-6 ont été sélectionnés comme noyau hydrophile et matériau extérieur hydrophobe en PET pour les filaments bicomposants trilobés. Cependant, PA6 et PA6-6 sont incompatibles et non miscibles au PET. L'enjeu majeur pour obtenir les fibres bicomposants recherchées est d'acquérir une adhérence suffisante à l'interface pour éviter le pré-clivage ou la séparation entre ces deux matériaux polymères. Afin d'améliorer leur miscibilité à l'interface, PA12 a été ajouté dans PA6 et PA6-6 à 5, 10, 15 % en poids via un procédé de mélange de polymères. les matériaux polymères jouent un rôle important. Afin de sélectionner les matériaux les plus appropriés pour la fibre bicomposant trilobée, des études rhéologiques ont été menées sur des mélanges purs et polymères à l'aide d'un rhéomètre capillaire. De plus, les propriétés hydrophiles de chaque polymère et de leurs mélanges ont également été testées sur des tissus tricotés avec des mesures d'angle de contact et de mèche. Pour évaluer l'effet du PA12 sur l'adhérence interfaciale du PET et du PA6, des fibres bicomposants PET/PA6 gaine/cœur ont été produites via un procédé de filage à l'état fondu et l'adhérence interfaciale a été étudiée par des techniques (test de traction, analyse thermique mécanique dynamique (DMTA), diffraction des rayons X à grand angle (WAXD), calorimétrie différentielle à balayage (DSC) et microscope électronique à balayage (SEM)). Sur la base des résultats obtenus à partir des techniques mentionnées ci-dessus, la composition la plus appropriée a été produite en fibres bicomposantes trilobées pour les tissus de confort thermique. Des études de simulation ont également été réalisées à l'aide du logiciel Compuplast 3D FEM pour optimiser les paramètres du processus de filage à l'état fondu et produire des fibres bicomposantes trilobées.Le textile fabriqué à partir de ces fibres bicomposantes innovantes montrera un phénomène d'auto-actionnement autonome, auto-responsabilisé et adaptatif à l'environnement. Cela contribuera à atténuer les consommations d'énergie plus élevées des systèmes de chauffage, de refroidissement et de ventilation intérieurs conventionnels et, à terme, à minimiser les consommations d'énergie globales et les problèmes climatiques
This study is part of Interreg European Project between Haute de France and Belgium. The project is called Photonitex. The aim of this project is to develop a personal thermal regulation intelligent textile that dynamically controls skin temperature. This work was done in collaboration between Centre Européen des Textiles Innovants (CETI) and School National Superior of Textile Arts and Industries (ENSAIT).The objective of this thesis is to develop a bicomponent fibers for thermal comfort textile. The literature review was done to select the most suitable polymer materials that are commonly used in textile industry. In addition, based on the literature review, the design of the trilobal bicomponent fibers was finalized to realize the dynamic thermal comfort textile. Moreover, used polymer materials must exhibit hydrophilic difference to achieve the dynamic thermal properties in fabrics. The inner material of this bicomponent trilobal fiber must be more hydrophilic than the outer material. PA6 and PA6-6 were selected as hydrophilic core and PET hydrophobic outer material for trilobal bicomponent filaments. However, PA6 and PA6-6 are incompatible and immiscible to PET. The major challenge to achieve the desired bicomponent fibers is to acquire a sufficient adhesion at the interface to avoid the pre-splitting or separation between these two polymer materials. In order to improve their miscibility at the interface PA12 was added in PA6 and PA6-6 at 5, 10, 15% wt % via polymer compounding process. In order to produce trilobal bicomponent filament via coextrusion melt spinning process, rheological behavior of the used polymer materials play an important role. To select the most suitable materials for trilobal bicomponent fiber, rheological studies were conducted on pure and polymer blends using capillary rheometer. In addition, hydrophilic properties of each polymer and their blends were also tested on knitted fabrics with contact angle and wicking measurements. To evaluate the effect of PA12 on PET and PA6 interfacial adhesion, bicomponent PET/PA6 sheath/core fibers were produced via melt spinning process and interfacial adhesion was investigated through techniques (tensile test, dynamic mechanical thermal analysis (DMTA), Wide Angle Xray Diffraction (WAXD), Differential scanning calorimetry (DSC), and Scanning Electron Microscope (SEM)). Based on the obtained results from the above mentioned techniques, the most suitable composition was produced in trilobal bicomponent fibers for thermal comfort fabrics. Simulation studies were also performed using Compuplast 3D FEM software to optimize the melt spinning process settings and produce trilobal bicomponent fibers.The textile made out of such innovative bicomponent fibers will show a self-actuation phenomenon are autonomous, self-empowered, and adaptive to the environment. This will help to mitigate the higher energy consumptions by conventional indoor heating, cooling, and ventilation systems and eventually minimizes the global energy consumptions and climate issues