Search results for "Thermal"
showing 10 items of 3576 documents
Morphology and thermal properties of foams prepared via thermally induced phase separation based on polylactic acid blends
2012
Blends of poly-l-lactic acid with two different types of polylactic acid with different average molecular weights (50,000 and 175,000 g/mol, respectively) in different proportions (90/10, 80/20 and 70/30) were utilized in order to produce biodegradable and biocompatible scaffolds for soft tissue engineering applications. The scaffolds were produced via thermally induced phase separation starting from ternary systems where dioxane was the solvent and water the non-solvent. Morphology (average pore size and interconnection) was evaluated by scanning electron microscopy. Foams apparent density was also evaluated (porosity ranges from 87% to 92%). Moreover, a differential scanning calorimetry …
Multifunctional properties of nanocomposites made by 1D and 2D graphene based fillers
2015
High aspect ratio graphene based fillers with different dimensionalities showed the ability to greatly modify rheological, mechanical, thermal and electrical properties of polymers at very low content. In this work, the effect of filler dimensionality on the multifunctional properties of an epoxy matrix reinforced by both carbon nanotubes (1D) and graphite nanoplatelets (2D) have been investigated across the percolation region. Keywords-- Carbon nanotube, Graphite nanoplatelet, nanocomposites, mechanical properties, ...
Stable anchoring of dispersed gold nanoparticles on hierarchic porous silica-based materials
2010
The nanometric organization of MOx (M = Co, Zn, Ni) domains partially embedded inside the mesoporous silica walls but accessible to the pore voids, which is achieved through a simple one-pot surfactant-assisted procedure, define optimal anchors for the nucleation and growth of gold nanoparticles, which in turn favours an exceptional thermal stability for the final Au-supported materials. As silica support we have selected a UVM-7 silica having a highly accessible architecture defined by two hierarchic pore systems. The combination of nanometric pore length, tortuous mesopores and MOx inorganic anchors favours the stability of the final Au/CoOx-UVM-7 nanocomposites.
CuO nanoparticle filled vinyl-ester resin nanocomposites: Fabrication, characterization and property analysis
2007
Abstract Both unmodified cupric oxide (CuO) nanoparticles and those functionalized with a bi-functional coupling agent methacryloxypropyl-trimethoxysilane (MPS) were used to fabricate vinyl-ester resin polymeric nanocomposites. The nanoparticle functionalization was observed to have a significant effect on the physical properties of the cupric oxide filled vinyl-ester resin nanocomposite. Thermal degradation study by thermo-gravimetric analysis (TGA) showed the increased thermo-stability in the functionalized-nanoparticle-filled vinyl-ester resin nanocomposites as compared with the unmodified-nanoparticle-filled counterparts. The more uniform particle dispersion and the chemical bond betwee…
CsPbX3/SiOx (X = Cl, Br, I) monoliths prepared via a novel sol-gel route starting from Cs4PbX6 nanocrystals
2019
We developed a facile synthesis of nanocomposite powders of CsPbX3 nanocrystals (NCs) embedded in silica. The synthesis starts from colloidal Cs4PbX6 NCs that are mixed with tetraethyl orthosilicate in the presence of nitric acid, which triggers the sol-gel reaction yielding the formation of SiOx and the conversion of starting NCs into CsPbX3 ones. The overall reaction delivers CsPbX3 NCs encased in a silica matrix. The resulting CsPbX3/SiOx nano-composite powders exhibited enhanced moisture and thermal stability in air. Also, when mixing different CsPbX3/SiOx samples having diverse anion compositions, no interparticle anion exchange processes were observed, which is a further indication th…
Synthesis and Properties of Amine-Cured Epoxy/Organophilic Layered Silicate Nanocomposites
2009
Epoxy-layered silicate composites have been prepared by dispersing an organically modified montmorillonite (Nanofil 919) in an epoxy resin and curing in the presence of an aromatic hardener. Dispersion of the layered silicate within the epoxy matrix was verified using X-ray diffraction and transmission electron microscopy revealing that interaction improves upon organic silicate modification. Flexural properties and toughness increase with the organic silicate loading whereas glass transition temperature decreases and thermal stability remains practically unmodified.
Novel non-destructive evaluation technique for the detection of poor dispersion of carbon nanotubes in nanocomposites
2019
Abstract A wide use of advanced carbon nanotube polymer composites can be boosted by new non-destructive evaluation (NDE) techniques that can test the quality of the products to ensure that their specifications are met. It is well known in literature that the parameter that far more than others can affect the enhancing capabilities of the carbon nanotubes is their dispersion. Here we have presented a novel NDE technique based on infrared thermography able to evaluate the dispersion of the added nanoparticles in polymer nanocomposites. The NDE technique was used to compare pairs of samples whose difference is represented only by the level of dispersion. It was found a significant difference …
Elastic Modulus and Thermal Conductivity of Thiolene/TiO2 Nanocomposites
2017
Metal oxide based polymer nanocomposites find diverse applications as functional materials, and in particular thiol-ene/TiO2 nanocomposites are promising candidates for dental restorative materials. The important mechanical and thermal properties of the nanocomposites, however, are still not well understood. In this study, the elastic modulus and thermal conductivity of thiol-ene/TiO2 nanocomposite thin films with varying weight fractions of TiO2 nanoparticles are investigated by using Brillouin light scattering spectroscopy and 3ω measurements, respectively. As the TiO2 weight fraction increases from 0 to 90%, the effective elastic longitudinal modulus of the films increases from 6.2 to 37…
Dispersions of nanosilica in biocompatible copolymers
2010
Dispersions of nanosilica in matrices of biocompatible copolymers were prepared by melt blending. Copolymers with variable molecular size at fixed hydrophilic/hydrophobic ratio and nanosilicas with different interfacial areas were studied. For comparison, a nanoclay was also investigated. The interfacial area played a relevant role in conferring peculiar properties on the nanohybrids. Amazingly, the macromolecule adsorbed on the nanosilica surface maintains some crystallinity which was quantitatively evaluated. In contrast, all the macromolecule anchored to the nanoclay surface is amorphous. The change of the crystalline state was reflected in the dielectric and the electrical conductivity …
NMR-investigation of the mechanism of silver mercaptide thermolysis in amorphous polystyrene
2007
Polymer-embedded silver clusters have been prepared by thermal decomposition of silver dodecylmercaptide previously dissolved in amorphous polystyrene. The morphology and structure of silver clusters have been determined by transmission electron microscopy (TEM) and large angle X-ray diffractometry (XRD), respectively. The mechanism involved in the thermolysis reaction was elucidated by different NMR techniques. The thermolysis produced thiol-derivatized silver clusters (i.e., silver clusters coated with a self-organized thiol monolayer, Agx(SC12H25)y) and had the effect of increasing the branching degree of polystyrene due to enhanced cross-linking.