Non-tissés de nanofibres de PA-6 en structure multicouches obtenus par electrofilage

Les non-tissés de nanofibres ont un intérêt majeur pour un grand nombre d'applications. Un grand nombre d'études en explorent les caractéristiques morphologiques. Ce travail fait suite aux travaux précédents portant sur la caractérisation mécanique des non-tissés de PA-6. L'objet de cette étude est l'observation morphologique des faciès de rupture des non-tissés, suite aux tests de traction et en fatigue. Cette investigation révèle une structure originale formée en multicouches jusqu'ici non observée

Elaboration and Characterization of Recycled PP/Clay Nanocomposites

In this paper, the elaboration and characterization of recycled polypropylene/Tunisian clay nanocomposites has been investigated. When recycled, polypropylene polymer is degraded and has poorer mechanical and rheological properties. To overcome this problem, we proposed to incorporate Tunisian clay nanoparticles in recycled polypropylene (rPP) matrix. The incorporation of Tunisian clay was performed in molten state using maleic anhydride grafted polypropylene (PP-g-MA) as compatibilizer. The dispersion of clay in rPP polymer was evaluated by scanning electron microscopy and Fourier transformed infrared spectroscopy. Thus, Tunisian clay was more dispersed in nanocomposites with the increase of Tunisian clay loading. In dead, the incorporation of silicate layers gave rise to a considerable increase of the static viscosity demonstrating the reinforcing effect of Tunisian clay nanofillers on rPP matrix. However, the increasing trend of morphological and rheological properties is lower when the clay content exceeds 5%

Synthesis and Characterization of Electrospun Nanofibers of Sr-La-Ce Oxides as Catalysts for the Oxidative Coupling of Methane

Catalytic nanofibers composed of La-Ce and Sr-La-Ce oxides were synthesized by the electrospinning method with 5 wt % Sr and different La/Ce molar ratios. The materials were obtained by calcining electrospun polymer composite fibers and were studied for the oxidative coupling of methane. The catalytic performance was compared with analogous Sr-La-Ce powder catalysts. SEM micrographs of Sr-La-Ce fibers (La/Ce: 0.1, 0.2, 1, and 3) showed nanostructures with homogeneous and uniform diameters (170-200 nm). In addition, the XRD patterns revealed the formation of crystalline solid solutions like LaxCeyOz. The strontium enhanced the CH4 conversion and C2 selectivity since it possibly generated structural defects that promote the formation of superoxide species. The SrLaCe3 nanofibers reached a CH4 conversion of 28.5% and C2 yield of 21.7% at 600 °C. The randomly packed nanofibers improved the heat and mass transfer properties due to their high geometric surface ratio with high bed porosity.Fil: Sollier, Brenda Maria del Valle. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Bonne, Magali. Université Haute-alsace.; FranciaFil: Khenoussi, Nabyl. Université Haute-alsace.; FranciaFil: Michelin, Laure. Université Haute-alsace.; FranciaFil: Miro, Eduardo Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Gómez, Leticia Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Boix, Alicia Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Lebeau, Benedicte. Université Haute-alsace.; Franci

Contribution to the study of nanofibers characterization obtained by electro-spinning : medical and composite application

La filature par voie électrostatique consiste à dissoudre un polymère dans un solvant, puis soumettre cette solution à un champ électrostatique intense. Différents paramètres influencent l'obtention, la production et la régularité des nanofilaments obtenus. Parmi ces paramètres, il y a des paramètres physiques inhérents à la cabine de filage, des paramètres électriques et des paramètres liés à la solution. Pour obtenir des nanofilaments, la première étape est de déterminer le ou les meilleurs couples polymère-solvant ainsi que les conditions expérimentales optimales pour obtenir à la fois des produits homogènes et reproductibles. L'obtention de nanofilaments de caractéristiques mécaniques et de structures données est complexe et dépend à la fois de paramètres de filage, mais aussi des propriétés de la solution. Une des propriétés les plus importantes de la solution est sa viscosité. Il a donc été nécessaire d'étudier, pour différents couples solvant-polymère (PA, PAN, PLA, PHEA) leur comportement rhéologique. Ces études rhéologiques ont permises d'expliquer les morphologies des matériaux obtenus par la conformation macromoléculaire de la solution. Les non-tissés de nanofibres obtenus ont été caractérisés par Microscopie à Forces Atomiques (AFM), Microscopie Electronique à Transmission (MET) et à Balayage (MEE) pour les aspects morphologiques. D'autres caractérisations, thermique (DSC), spectroscopique (FTIR) et mécaniques (traction et indentation) ont complété la caractérisation de ces matériaux. A l'issue de l'étude précédente, les nanofibres ont été employées dans deux applications. (1) L'incorporation et la compatibilisation de nanorenforts à l'intérieur d'une matrice polymère (Polyacrylonitrile). L'influence sur les propriétés géométriques des nanofibres de façon globale, et plus finement, la morphologie de surface, ont été observées par une analyse AFM de nano-rugosité. (2) La réalisation à partir d'un biopolymère d'un guide tubulaire permettant la croissance cellulaire et la reconnexion de nerfs sectionnés. Il a fallu pour cela remplir un cahier des charges rigoureux en termes de dimensionnement, de structure, et de propriétés mécaniques.Electrospinning is a process to produce the fibers in nano scale by injecting the polymer solution through a metallic needle to a high voltage electrical field. Different parameters affect the process production and regularity of obtained nano-web. Among these parameters, there are physical parameters depending on the electrospinning booth, electrical parameters and polymer solution properties. For nanofibers production, the first step is to determine the most efficient polymer-solvent pairs and the optimal experimental conditions for both homogeneous and reproducible products. Obtaining mechanical and morphological properties of nanofibers nonwowen is complex and depends on the electrospinning parameters, but also the solution properties. One of the most important properties of the solution is its viscosity. It was therefore necessary to study for the selected pairs (PA, PAN, PLA, PHEA) their rheological behaviour. These rheological studios allow to explain the morphology of obtained nanofibers, which could be explained by the conformation of the macromolecules in the solution. Nonwoven nanofibers obtained were characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) for morphological aspects. Other characterizations, thermal (DSC), spectroscopie (FTIR) and mechanical (tensile and indentation) completed the characterization of these materials. After these previous studios, the nanofibers have been used in two applications. (1) The incorporation of nanofillers and compatibilization within a polymer matrix (Polyacrylonitrile). The influence on the geometric properties of nanofibers, and surface morphology were observed by AFM nano-roughness analysis. (2) The production by electrospinning of a guide tube for cell growth and reconnection of severed nerves: from a biopolymer. The produced material had to meet strict specifications in terms of size, structure, and mechauical properties

Contribution à l'étude et à la caractérisation de nanofibres obtenues par électro-filage : Application aux domaines médical et composite

Electrospinning is a process to produce the fibers in nano scale by injecting the polymer solution through a metallic needle to a high voltage electrical field. Different parameters affect the process production and regularity of obtained nano-web. Among these parameters, there are physical parameters depending on the electrospinning booth, electrical parameters and polymer solution properties. For nanofibers production, the first step is to determine the most efficient polymer-solvent pairs and the optimal experimental conditions for both homogeneous and reproducible products. Obtaining mechanical and morphological properties of nanofibers nonwowen is complex and depends on the electrospinning parameters, but also the solution properties. One of the most important properties of the solution is its viscosity. It was therefore necessary to study for the selected pairs (PA, PAN, PLA, PHEA) their rheological behaviour. These rheological studios allow to explain the morphology of obtained nanofibers, which could be explained by the conformation of the macromolecules in the solution. Nonwoven nanofibers obtained were characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) for morphological aspects. Other characterizations, thermal (DSC), spectroscopie (FTIR) and mechanical (tensile and indentation) completed the characterization of these materials. After these previous studios, the nanofibers have been used in two applications. (1) The incorporation of nanofillers and compatibilization within a polymer matrix (Polyacrylonitrile). The influence on the geometric properties of nanofibers, and surface morphology were observed by AFM nano-roughness analysis. (2) The production by electrospinning of a guide tube for cell growth and reconnection of severed nerves: from a biopolymer. The produced material had to meet strict specifications in terms of size, structure, and mechauical properties.La filature par voie électrostatique consiste à dissoudre un polymère dans un solvant, puis soumettre cette solution à un champ électrostatique intense. Différents paramètres influencent l'obtention, la production et la régularité des nanofilaments obtenus. Parmi ces paramètres, il y a des paramètres physiques inhérents à la cabine de filage, des paramètres électriques et des paramètres liés à la solution. Pour obtenir des nanofilaments, la première étape est de déterminer le ou les meilleurs couples polymère-solvant ainsi que les conditions expérimentales optimales pour obtenir à la fois des produits homogènes et reproductibles. L'obtention de nanofilaments de caractéristiques mécaniques et de structures données est complexe et dépend à la fois de paramètres de filage, mais aussi des propriétés de la solution. Une des propriétés les plus importantes de la solution est sa viscosité. Il a donc été nécessaire d'étudier, pour différents couples solvant-polymère (PA, PAN, PLA, PHEA) leur comportement rhéologique. Ces études rhéologiques ont permises d'expliquer les morphologies des matériaux obtenus par la conformation macromoléculaire de la solution. Les non-tissés de nanofibres obtenus ont été caractérisés par Microscopie à Forces Atomiques (AFM), Microscopie Electronique à Transmission (MET) et à Balayage (MEE) pour les aspects morphologiques. D'autres caractérisations, thermique (DSC), spectroscopique (FTIR) et mécaniques (traction et indentation) ont complété la caractérisation de ces matériaux. A l'issue de l'étude précédente, les nanofibres ont été employées dans deux applications. (1) L'incorporation et la compatibilisation de nanorenforts à l'intérieur d'une matrice polymère (Polyacrylonitrile). L'influence sur les propriétés géométriques des nanofibres de façon globale, et plus finement, la morphologie de surface, ont été observées par une analyse AFM de nano-rugosité. (2) La réalisation à partir d'un biopolymère d'un guide tubulaire permettant la croissance cellulaire et la reconnexion de nerfs sectionnés. Il a fallu pour cela remplir un cahier des charges rigoureux en termes de dimensionnement, de structure, et de propriétés mécaniques

Measuring of Electrical Properties of MWNT-Reinforced PAN Nanocomposites

Nano-web sheets of polyacrylonitrile (PAN) reinforced by carbon nanotubes (CNT) were prepared by electrospinning process. Multi wall nanotubes (MWNT) were dispersed mechanically by high shear mixing using a homogenizer device. It has been found that the spinning solution presented an electrical percolation threshold less than 0.5 wt.% of MWNT. Electrical volume and surface conductivity of the obtained nano-webs was studied by measuring the electrical volume resistance and surface resistance thanks to home-made plate electrodes. Scanning electron microscope (SEM) has been used to characterize the nano-web sheets produced. The average filament diameters range from 320 to 750 nm depending on the concentration of CNT and of PAN. From an electrical point of view, it has been observed that the electrical volume conductivity increases by about six orders of magnitude from 2×10−12 S/m for pristine PAN to 4×10−6 S/m for PAN charged by MWNT. Increasing the pressure on the specimen induces an exponential decrease of the volume resistivity while surface resistivity shows no significant changes, neither between pristine PAN and reinforced nano-webs, nor among reinforced nano-web in relation to MWNT concentration (in the limit of the study). This observed behavior is very interesting in the context of sensor developments

An in Situ Crystal Growth of Metal Organic Frameworks-5 on Electrospun PVA Nanofibers

In this study, a simple, general and straightforward method for growing metal-organic frameworks (MOFs) crystals directly on nanofibers is presented. A chelating polymer was first blent with metal cation and then electrospun. The obtained nanofibers were immersed in a linker solution. Metal cations were released and the metal-organic frameworks crystals were grown on the fibers’ surface. In this work, this method was tested with polyvinyl alcohol as chelating polymer, Zn2+ as metal cation and Terephthalic acid as linker. The pair cation/linker corresponds to the MOF-5. The latter is a robust metal organic framework formed from Zn4O nodes with 1,4-benzodicarboxylic acid struts between the nodes. SEM images revealed that the MOF-5 nanocrystals have grown along the PVA/Zn2+ nanofibers that served as the crystals’ growth template by providing the Zn2+ ions. This result was also confirmed by infrared spectroscopy, which indicates the presence of characteristic bands of MOF-5 in the modified nanofibers spectrum. Moreover, the X-ray diffraction showed that MOF-5 material was well crystallized on the nanofibers surface according to a cubic symmetry with a space group Fm-3m and a lattice constant a = 25.8849 Å

Filage et caractérisation de nanofilaments par voie élètrostatique

Le procédé de filage électrostatique est une technique de fabrication de nanofibres applicable à de nombreux polymères. Le principe consiste à dissoudre un polymère dans un solvant et à introduire cette solution dans un champ électrique intense. Un paramètre important de la solution est la viscosité, il est intéressant d’en étudier le comportement rhéologique et d’établir des relations avec les paramètres du procédé de filage et les propriétés mécaniques des matériaux obtenus

Electrospinning Nonwovens of Polyacrylonitrile / synthetic Na-Montmorillonite Composite Nanofibers

International audienceNonwovens of polymer/clay composite nanofibers (namely, Polyacrylonitrile/Na-montmorillonite, PAN/Na-MMT) are produced by electrospinning a solution of PAN in dimethylformamide containing synthetic Na-MMT. The influence of both Na-MMT amount and applied voltage on the properties of electrospun composite nonwovens was studied. Scanning electron microscopy (SEM), X-ray diffraction (XRD) thermogravimetric analysis (TGA-DTA), were used to evaluate the morphology, structure and thermal properties of composite nanofibers. SEM observations revealed that increasing the amount of Na-MMT in the solution or the applied voltage increases the average diameter of electrospun composite nanofibers. The prepared composite showed a higher thermal stability that the pristine PAN nanofibers. It was proven that the ion exchange properties of Na-MMT were maintained in the obtained composite

Study of Mechanical Properties of Electrospun PA-6 Nanowebs and Electrospun PA-6/ B Composite as Substitution Membrane for Congenital Diaphragmatic Hernia Treatment

International audienceThe diaphragm is the main breathing muscle in the body which is divided into two parts made of both muscles (peripheral part) and tendons (central part). Congenital diaphragmatic hernia (CDH) is a rare defect that occurs while the diaphragm malformation happens between the fourth week and the third month of pregnancy. This process prevents the lungs from growing normally and it affects about 1 over 2,500 babies.As a current treatment at Strasbourg Civil hospital in France in the case of big hole size, abdominal organs are moved back to the abdominal cavity and the hole will be closed by Gore-Tex prosthetic membrane. The problem is that by growing up the patient, who is mostly a baby, the existing hole in the diaphragm will grow as well. Gore-Tex implant membrane is not elastic enough so the time passing by there is a need to re operate the patients. The prosthesis in 43% of the cases will be removed because of hernia recurrence. To solve this problem, producing a new prosthesis by using electrospinning method could be a solution to reduce the number of planned re operation.Mechanical test on pork’s diaphragm has been done in order to obtain a mechanical idea of feasible and the nearest case to human diaphragm. A comparison between the tensile mechanical properties of tendon part of diaphragm and electrospun PA-6 nanofibers due to its good mechanical and physical properties by using single needle electrospinning machine with 3 different times of electrospinning (3,6 and 9 hours of electrospinning) was done, the results showed that 3h electrospun PA-6 nanofibers are close to tendon in the level of interval force but the elasticity should be increased.In order to increase the elasticity of electrospun PA-6 nanofibers, a B material is used during the electrospinning process. Electrospun PA-6/ B composite with different time of electrospinning is produced. The average diameter of produced nanofibers is close to the one expected in the specification