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Polymer nanostructured materials for high temperature applications / Joseph H. Koo in SAMPE JOURNAL, Vol. 41, N° 2 (03-04/2005)

[article]  inSAMPE JOURNAL > Vol. 41, N° 2 (03-04/2005) . - p. 7-19 Titre : Polymer nanostructured materials for high temperature applications Type de document : texte imprimé Auteurs : Joseph H. Koo, Auteur ; Louis Pilato, Auteur Année de publication : 2006 Article en page(s) : p. 7-19 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 668.4 Plastiques, vinyles Résumé : Polymer nanostructured materials for high temperature applications are formed bu introducing a nanophase into several different polymer systems. These applications include fire retardant coatings, rocket propulsion insulation, rocket nozzle abrasive materials, carbon/carbon composites, and damage tolerant high performance epoxy carbon fiber reinforced composites systems. The polymer resins cinsisting of thermosets like phenolic, cyanate ester, and epoxy; thermoplastics such as Nylon 11 and poluvinyl acetate-acrylic copolymer; and thermoplastic elastomer like polyamide silicone copolymer. Using appropriate processing conditions to uniformly disperse various nanoparticleslike MMt nanoclay, nanosilica, carbon nanofiber, and POSS, nanocomposite morphology was developed within the polymer continuous phase as evidenced by WAXD, TEM, and SEM analyses. Structural property improvements due to the presence of a "nanophase" within the polymer matrix are supported by cone calorimeter data of nanomodified fire retardant coatings exhibiting delayed ignition times, reduced peak heat release rates, and synergism; reduced erosion and lower backside heat-soaked temperature for nanomodified rocket nozzle materials; enhanced thermo-oxidative resistance at intermediate temperatures of 700° to 1,200°F for nanomodified carbon/carbon composite, and improved toughened nanocomposite epoxy carbon fiber reinforced polymer matrix system. Note de contenu : - Processing of nanoparticles into polymers - Types of polymers - Analyses - Selection of nanoparticles - Fire-retardant nanocomposite coatings - Nanostructured materials for propulsion systems - Nanocomposite rocket ablative materials (NRAM) - Nanomodified carbon/carbon composites (NCCC) - Damage tolerant high performance epoxy system Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=23222 [article]

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High aspect ratio sub-micron and nano-scale metal filaments / George Hansen in SAMPE JOURNAL, Vol. 41, N° 2 (03-04/2005)

[article]  inSAMPE JOURNAL > Vol. 41, N° 2 (03-04/2005) . - p. 24-33 Titre : High aspect ratio sub-micron and nano-scale metal filaments Type de document : texte imprimé Auteurs : George Hansen, Auteur Année de publication : 2006 Article en page(s) : p. 24-33 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 668.4 Plastiques, vinyles Résumé : The fabrication and applications of high aspect, sub-micron and nanoscale metal filaments, know commercially as Nanostrands is described. While there are many contemplated uses for nanostrands, most investigations of the material to date have focused on electrical conductivity in polymers and composites. The superior conductivity of metal and the high aspect ratio permits a wide variety of technology insertion techniques. The nanostrands may be added to a matrix, or the matrix may be infiltrated into a nanostrand perform. Many different applications, including polymer resins, adhesives, elastomers, paints, polymer concrete and many different composite designs have been rendered highly conductive by the addition of small fractions of the material. Nanostrands have been found to be particularly effective in controlling electromagnetic effects, such as electrostatic discharge, lightning strike and electromagnetic shielding. Nanostrand oxides are described, as are nanostrand aluminides, which retain their unique characteristics to over 500°C. Finally, the extension of the technology to create nickel coated carbon nanofibers is described and the future of these materials in the world of nanotechnology is contemplated. Note de contenu : - Fabrication process - General applications - The role of nanostrands in electronic nanomaterials - Two paths to conductivity - Polymer infiltrated nanostrand preforms - Nanostrands mixed into polymers - Other parameters that effect volume resistivity - Selected electronic materials applications - Fiber reinforced composites - Electromagnetic effects - Aluminides and oxides - Nickel coated carbon nanofibers Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=23223 [article]

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Fabrication, characterization and mechanical properties of nanophased carbon prepreg laminates / Hassan Mahfuz in SAMPE JOURNAL, Vol. 41, N° 2 (03-04/2005)

[article]  inSAMPE JOURNAL > Vol. 41, N° 2 (03-04/2005) . - p. 40-48 Titre : Fabrication, characterization and mechanical properties of nanophased carbon prepreg laminates Type de document : texte imprimé Auteurs : Hassan Mahfuz, Auteur ; Mohammed A. Baseer, Auteur ; Vijaya K. Rangari, Auteur ; Shaik A. K. Jeelani, Auteur Année de publication : 2006 Article en page(s) : p. 40-48 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 668.4 Plastiques, vinyles Résumé : An innovative manufacturing of unidirectional nano-phased carbon fiber laminates doped with b-SiC nanoparticles was developed using the combination of filament winding and online solution impregnation method. The technique was developed to prepare nano-phased carbon prepreg used in the fabrication of the nano-phased laminates were successfully manufactured. The sample coupons were characterized by TGA (Thermo-gravimetric analysis), DSC (Differential scanning calorimetry) and SEM (Scanning electron microscope). TGA results showed that the nano-phased laminates were thermally more stable (about 7°C) than the neat counter parts. DSC results indicate the maximum cross-linking of the polymer chain in the presence of SiC nanoparticles. SEM micrographs show that the carbon fiber used are ~10 micrometers in diameter and the nanophased resin is uniformly wetted all over the fiber volume. Flexure test results revealed significant improvement of 32% in flexural strength and 20% in modulus when compared to the neat system. Note de contenu : - FABRICATION PROCEDURE FOR THE PREPREG LAMINATES : Dispersion of nanoparticles in the liquid prepreg resin - Wetting during solution pre-impregnation - Solvent removal from the prepreg - Hot melt consolidation of prepregs - EXPERIMENTAL : Flexure test - Test fixture - Test specimen - Test procedure - Data acquisition - RESULTS AND DISCUSSION : Thermal analysis - SEM analysis - Flexure test Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=23224 [article]

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Using a carbon nanotube additive to make electrically conductive commercial polymer composites / Marni Rutkofky in SAMPE JOURNAL, Vol. 41, N° 2 (03-04/2005)

[article]  inSAMPE JOURNAL > Vol. 41, N° 2 (03-04/2005) . - p. 54-55 Titre : Using a carbon nanotube additive to make electrically conductive commercial polymer composites Type de document : texte imprimé Auteurs : Marni Rutkofky, Auteur ; Mark Banash, Auteur ; Ram Rajagopal, Auteur ; Jian Chen, Auteur Année de publication : 2006 Article en page(s) : p. 54-55 Langues : Américain (ame) Index. décimale : 668.4 Plastiques, vinyles Résumé : Carbon nanotubes (CNTs) have physical properties that exceed those of commonly used materials. With a tensile strength eight times of stainless steel and with a thermal conductivity five time that of copper, CNTs are obvious choices for creating a new class of composite materials. Their inclusion in a polymer or ceramic matrix holds the potential to boost the host material's electrical, mechanical, or thermal values by orders of magnitude, well above the performance possible with traditional fillers such as carbon black or ultra fine metal powders. But although CNTs have exceptional physical properties, incorporating them into other materials has been inhibited bu the surface chemistry of carbon. Problems such as phase separation, aggregation, poor dispersion within a matrix, and poor adhesion to the host must be overcome. Zyvex has overcome these restrictions by developing a new surface treatment technology that optimizes the interaction between CNTs and the host matrix. Company researchers can create a multi-functional bridge between the CNT sidewalls and the host matrix. Company researchers can create a multi-functional bridge between the CNT sidewalls and the host material or solvent. The power of this bridge is demonstrated in Figure 1 which shows a fracture surface in a polycarbonate composite (made using Zyvex's technology). Raw nanotubes often interact poorly with a matrix - a fracture expels them and leaves behind voids in the material. Figure 1 show that the processed tubes remain in the matrix even after the fracture, indicating strong interaction with the host. The processed nanotubes demonstrate excellent dispersion and enhanced compatibility with commercial polymers, including polycarbonates, polystyrenes, and epoxies. With this technology, manufacturers and end-users can now take full advantage of the powerfull capabilities of the CNTs. In this note we specifically demonstrate how polymer composites with electrical conductivity spanning the range from insulating to semiconducting can be prepared with current Zyvex technology. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=23225 [article]

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