Showing papers on "Thermal stability published in 2006"
TL;DR: Study of the gas adsorption and thermal and chemical stability of two prototypical members, ZIF-8 and -11, demonstrated their permanent porosity, high thermal stability, and remarkable chemical resistance to boiling alkaline water and organic solvents.
Abstract: Twelve zeolitic imidazolate frameworks (ZIFs; termed ZIF-1 to -12) have been synthesized as crystals by copolymerization of either Zn(II) (ZIF-1 to -4, -6 to -8, and -10 to -11) or Co(II) (ZIF-9 and -12) with imidazolate-type links. The ZIF crystal structures are based on the nets of seven distinct aluminosilicate zeolites: tetrahedral Si(Al) and the bridging O are replaced with transition metal ion and imidazolate link, respectively. In addition, one example of mixed-coordination imidazolate of Zn(II) and In(III) (ZIF-5) based on the garnet net is reported. Study of the gas adsorption and thermal and chemical stability of two prototypical members, ZIF-8 and -11, demonstrated their permanent porosity (Langmuir surface area = 1,810 m 2 /g), high thermal stability (up to 550°C), and remarkable chemical resistance to boiling alkaline water and organic solvents.
5,512 citations
TL;DR: Collagen/elastin (1:1) meshes were stabilized by crosslinking with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) without altering their original morphology, which afforded materials with a high thermal stability.
599 citations
TL;DR: In this article, halloysite nanotubes (HNTs) with hollow nanotubular structures were used as a new type filler for poly(propylene) (PP).
433 citations
TL;DR: A novel guest-free metal organic framework (GFMMOF) is synthesized and structurally characterized that demonstrates a remarkable thermal stability, a unique ability to separate methanol from dimethyl ether or water, and is among the microporous MOFs having the highest adsorbed hydrogen density.
Abstract: A novel guest-free metal organic framework (GFMMOF) is synthesized and structurally characterized. It contains one-dimensional close-packed open channels with a pore diameter of 4.5 A. It demonstrates a remarkable thermal stability, a unique ability to separate methanol from dimethyl ether or water, and is among the microporous MOFs having the highest adsorbed hydrogen density (0.054 g/cm3 at 77 K and 1 atm).
427 citations
TL;DR: In this article, the thermal stability of the neat LiPF6 salt and of 1 molal solutions of Li-ion battery solvents was studied with thermogravimetric analysis (TGA) and on-line FTIR.
386 citations
TL;DR: The significant thermal and chemical stability of the peptide nanotubes demonstrated here points toward their possible use in conventional microelectronic and microelectromechanics processes and fabrication into functional nanotechnological devices.
Abstract: The diphenylalanine peptide, the core recognition motif of the β-amyloid polypeptide, efficiently self-assembles into discrete, well-ordered nanotubes. Here, we describe the notable thermal and chemical stability of these tubular structures both in aqueous solution and under dry conditions. Scanning and transmission electron microscopy (SEM and TEM) as well as atomic force microscopy (AFM) revealed the stability of the nanotubes in aqueous solution at temperatures above the boiling point of water upon autoclave treatment. The nanotubes preserved their secondary structure at temperatures up to 90 °C, as shown by circular dichroism (CD) spectra. Cold field emission gun (CFEG) high-resolution scanning electron microscope (HRSEM) and thermogravimetric analysis (TGA) of the peptide nanotubes after dry heat revealed durability at higher temperature. It was shown that the thermal stability of diphenylalanine peptide nanotubes is significantly higher than that of a nonassembling dipeptide, dialanine. In addition ...
360 citations
TL;DR: In this article, the mechanism of thermal degradation of substituted polyhedral oligomeric silsesquioxanes (POSS) cages is studied in both inert atmosphere and in air, and the results show that Isobutyl and octyl substituted POSS undergo an almost complete evaporation when heated in inert atmosphere.
342 citations
TL;DR: In this paper, the melting enthalpy results of low-density polyethylene (LDPE) and linear low density polyethylenes (LLDPE), with different copper contents were prepared by melt mixing and the copper powder particle distributions were found to be relatively uniform at both low and high copper contents.
315 citations
TL;DR: In this paper, a polyurethane/multi-walled carbon nanotube elastomer composite was synthesized and the properties of the composite were characterized by dynamic mechanical thermal analysis, thermogravimetric analysis and tensile testing.
308 citations
TL;DR: The robust metal-organic framework compound, [Zn(2)(L)](infinity) (II), which has very high thermal stability and is chemically inert, is synthesized by hydrothermal reaction of ZnCl(2) and 4,4'-bipyridine-2,6,2',6'-tetracarboxylic acid.
Abstract: The robust metal−organic framework compound {[Zn2(L)]·4H2O}∞ I has been synthesized by hydrothermal reaction of ZnCl2 and 4,4‘-bipyridine-2,6,2‘,6‘-tetracarboxylic acid (H4L). Compound I crystallizes in a chiral space group, P42212, with the chirality generated by the helical chains of hydrogen-bonded guest water molecules rather than by the coordination framework. Removal of guest water molecules from the crystal affords the porous material, [Zn2(L)]∞ (II), which has very high thermal stability and is chemically inert. The N2 isotherm of II at 77 K suggests a uniform porous structure with a BET surface area of 312.7 m2/g and a remarkably strong interaction with N2 molecules (βE0 = 29.6 kJ mol-1). II also exhibits significant gas storage capacities of 1.08 wt % for H2 at 4 bar and 77 K and 3.14 wt % (44.0 cm3/g, 67 v/v) for methane at 9 Bar at 298 K. The adsorption behavior of II toward organic solvent vapors has also been studied, and isotherms reveal that for different solvent vapors adsorption is domin...
289 citations
TL;DR: In this article, the effect of the addition of two different compatibilizing agents, maleic anhydride (MA)-grafted polypropylene (MAPP), to bio-flour-filled, Polypropylene and low-density polyethylene (LDPE) composites was investigated.
TL;DR: Thermogravimetric analysis (TGA) suggests that the Chi-BMIM.BF(4)-Hb composite has higher thermal stability than Chi-Hb itself and was characterized by UV-visible spectra, indicating excellent stability in solution and good biocompatibility for protein.
TL;DR: In this paper, a modified poly(phthalazinon ether sulfone ketone) membrane has been prepared for application in alkaline direct alcohol fuel cells, which exhibits a thermal stability below 150°C.
TL;DR: In this paper, a new parameter, namely the Stability Index, was introduced to quantify the thermal stability of zeolites, which is based on the zeolite breakdown temperatures from X-ray diffraction studies.
TL;DR: In this article, two Dy-Mn polymers with 3D-4f mixed metals and high symmetry (S6) with luminescent selectivity for Mg2+ were presented.
Abstract: Two Dy-Mn polymers, {[Dy(L1)3Mn(1.5)(H2O)3]3.125H2O}n (1, L1 = pyridine-2,6-dicarboxylic acid) and {[Dy(L2)3Mn(1.5)(H2O)6]8.25H2O}n (2, L2 = 4-hydroxylpyridine-2,6-dicarboxylic acid), with high symmetry (S6) have been prepared. Polymer 1 has a nanoporous 3D framework with channel of about 17.6 A diameter, while 2 has a honeycomb-type 2D structure with the cavity of approximately 14.4 A diameter. In the construction of multidimensional porous polymers with 3d-4f mixed metals, it is the first observation that a ligand substituent effect leads to dramatic differences in the structures formed. Luminescent studies reveal that the emission intensities of 1 and 2 increase significantly upon the addition of Mg2+, whereas the introduction of other metal ions leaves the intensity unchanged or even weakens it; hence, both of them may serve as good candidates of Mg2+ luminescent probes. To our knowledge, complex 1 is also the first example of a 3d-4f metal-based nanoporous polymer to exhibit luminescent selectivity for Mg2+. Magnetic susceptibility measurements reveal a rather rare ferromagnetic interaction in 2. Thermal gravimetric analyses and powder X-ray diffraction investigations have also been performed, suggestive of high thermal stability of 1.
TL;DR: In this article, the structural properties, thermal behaviors, and mechanical properties were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy, differential scanning calorimetry, thermogravimetry analyses, and an Instron universal testing machine.
Abstract: Nanocomposites of chitosan and nanoclays (MMT-Na+ and Cloisite 30B) were prepared by solvent casting. The structural properties, thermal behaviors, and mechanical properties were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy, differential scanning calorimetry, thermogravimetry analyses, and an Instron universal testing machine. XRD and TEM results indicated that an exfoliated structure was formed with addition of small amounts of MMT-Na+ to the chitosan matrix. Intercalation along with some exfoliation occurred with up to 5 wt % MMT-Na+. Micro-scale composite (tactoids) formed when Cloisite 30B was added to the chitosan matrix. Surface roughness increased with addition of a small amount of clay. Tensile strength of a chitosan film was enhanced and elongation-at-break decreased with addition of clay into the chitosan matrix. Melt behavior and thermal stability did not change significantly with addition of clays. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1684–1691, 2006
TL;DR: In this article, it was demonstrated that TTNT consisted of a trititanate structure with general formula Na x H 2− Ti 3 O 7 · n H O, where 0
TL;DR: In this article, the biodegradable poly(lactic acid) (PLA)/montmorillonite (MMT) nanocomposites were successfully prepared by the solution mixing process of PLA polymer with organically modified montmorillonites (m-MMT), which was first treated by n-hexadecyl trimethyl-ammonium bromide (CTAB) cations and then modified by biocompatible/biodegradability chitosan to improve the chemical similarity between the PLA and m-MMTs.
TL;DR: In this paper, Li0.45(Ni0.8Co0.15Al0.05)O2 and Li 0.55(Ni1/3Co 1/3Mn 1/5Mn1/5 )O2 powders were delithiated using NO2BF4 oxidizer in an acetonitrile medium.
TL;DR: A lanthanide metal-organic framework, Dy(BTC)(H2O), with excellent thermal stability shows a high surface area, 655 m(2) g(-1), high hydrogen and carbon dioxide storage capability, and available Lewis-acid metal sites which could be anticipated to use in catalysis and metal-site specific chemical sensor.
TL;DR: In this paper, a simple and widely applicable methodology for the synthesis of multicomponent mesostructured metal oxides (MMMOs) from the combination of inexpensive and commercially available polymers with metal alkoxides solubilized in a sol−gel solution consisting of acetic acid, hydrochloric acid, and ethanol (AcHE).
Abstract: Multicomponent metal oxides have attracted attention for their potential use in electronic, (photo)catalytic, photovoltaic, and energy storage applications. The ability to simultaneously control the nanoscale structure and composition of such materials using simple and inexpensive routes is important for that potential to be realized. Here we introduce a simple and widely applicable methodology for the synthesis of multicomponent mesostructured metal oxides (MMMOs) from the combination of inexpensive and commercially available polymers with metal alkoxides solubilized in a sol−gel solution consisting of acetic acid, hydrochloric acid, and ethanol (AcHE). MMMOs obtained utilizing the AcHE system have tunable pore structures, a high degree homogeneity, and in certain cases thermal stability above 1000 °C. The ability to easily process these diverse MMMOs in the form of thin films, free-standing membranes, and monoliths provides distinct advantages over previously reported MMO synthesis proceduresespecially ...
TL;DR: In this paper, a simple method to prepare nanocrystalline hydroxyapatite (nHAP) is performed using a precipitation method assisted with microwave heating method, which can be reported notably with high reproducibility and productivity.
TL;DR: In this article, the authors investigated the reaction of arc-evaporated cubic Al0.7Cr0.3N hard coatings in Ar up to 1450 °C.
TL;DR: The long term thermal stability of ionic liquids containing dicyanamide or tricyanomethide anions is significantly lower than might be expected from temperature ramped TGA studies, and these anions, combined with N-based cations, yield polymeric products during thermal decomposition.
TL;DR: Investigating bulk heterojunction morphology and photovoltaic performance upon annealing, it is observed that polythiophene with 91% regioregularity maintains equivalent electronic properties but forms a more thermally stable interpenetrating network with PCBM than polythyphene with regiOREgularity >96%.
Abstract: Regioregularity has been shown to be an important aspect for the properties of poly(3-hexylthiophene) both in the pristine material and in bulk heterojunction photovoltaics with the fullerene derivative PCBM. Here we present a straightforward method to adjust the effective regioregularity of poly(3-hexylthiophene) by introducing 3,4-dihexylthiophene into the polymer chain. By investigating bulk heterojunction morphology and photovoltaic performance upon annealing, we observe that polythiophene with 91% regioregularity maintains equivalent electronic properties but forms a more thermally stable interpenetrating network with PCBM than polythiophene with regioregularity >96%.
TL;DR: In this paper, the photocatalytic activity of the samples was evaluated by the decomposition of ethylene in air under visible light (lambda > 450 nm) illumination, and it was shown that nitrogen was doped into the lattice of TiO2 by the thermal treatment of NH3-adsorbed hydrous gels.
Abstract: Mesoporous nanocrystalline TiO2-xNx and TiO2-xNx/ZrO2 visible-light photocatalysts have been prepared by a sol-gel method. The photocatalysts were characterized by XRD, N2 adsorption-desorption, TEM, XPS, UV/Vis, and IR spectroscopy. The photocatalytic activity of the samples was evaluated by the decomposition of ethylene in air under visible light (lambda > 450 nm) illumination. Results revealed that nitrogen was doped into the lattice of TiO2 by the thermal treatment of NH3-adsorbed TiO2 hydrous gels, converting the TiO2 into a visible-light responsive catalyst. The introduction of ZrO2 into TiO2-xNx considerably inhibits the undesirable crystal growth during calcination. Consequently, the ZrO2-modified TiO2-xNx displays higher porosity, higher specific surface area, and an improved thermal stability over the corresponding unmodified TiO2-xNx samples.
TL;DR: In this paper, the effect of fiber treatments on thermal stability of flax fiber and crystallization of polypropylene composites was investigated using thermogravimetry (TG) analysis.
TL;DR: In this article, single-walled carbon nanotube (SWNT) and polyvinylidene fluoride (PVDF) composites were fabricated by dispersion of SWNT in an aqueous surfactant solution, followed by mixing with PVDF powder, filtration and hot pressing.
Abstract: Single-walled carbon nanotube (SWNT)–poly(vinylidene fluoride) (PVDF) composites were fabricated by dispersion of SWNT in an aqueous surfactant solution, followed by mixing with PVDF powder, filtration and hot pressing. The thermal properties of the composites at various SWNT volume fraction up to 49% were investigated. The coefficient of thermal expansion (CTE) was decreased with increase of the SWNT content. The thermal conductivity increased with temperature in the temperature range from 25 to 150 °C. The thermal conductivity was enhanced, but not up to the level required by heat sink applications. The melting point was not affected significantly by the addition of SWNT, but the degree of crystallinity was increased and the decomposition temperature of the matrix was decreased. The large number of junctions among SWNT largely offsets the benefit of the high thermal conductivity of SWNT. In addition, the impurity and defects in SWNT are believed to limit the thermal conductivity of the composites. Lastly, the reduced thermal stability of the composite compared to the matrix might result from the presence of the metal catalyst contained in the SWNT.
TL;DR: In this article, intermediate-high molecular weight poly[2,2-(m -phenylene)-5,5-bibenzimidazole] has been produced by mixing 3,3′,4, 4,4′-tetraminobiphenyl and isophthalic acid in polyphosphoric acid as polycondensing agent and triphenyl phosphite as catalyst.
TL;DR: In this paper, the effects of H2O2 oxidation without metal catalysts and under neutral conditions on morphologies and structures of the multiwalled carbon nanotubes (MWNTs) were analyzed.
Abstract: We studied the effects of H2O2 oxidation without metal catalysts and under neutral conditions on morphologies and structures of the multiwalled carbon nanotubes (MWNTs). The formation of surface functional groups and changes in nanotube structures, morphology, and thermal stability during oxidation were analysized by X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectra, high-resolution transmission electron microscopy, and thermogravimetric analysis. Several functional groups such as carboxylic (−COOH), carbonyl (−CO), and hydroxyl (−OH) groups were formed on the surface of MWNTs; however, hydroxyl groups were preferentially formed and reached a maximum atomic concentration of about 46% in 4 days of oxidation. The graphitization degree decreased in the first day of oxidation; however, it readily increased in the continued oxidation days.