Influence of polyimide precursor synthesis route and ortho-position functional group on thermally rearranged (TR) polymer properties: Pure gas permeability and selectivity

2014 ◽  
Vol 463 ◽  
pp. 73-81 ◽  
Author(s):  
David F. Sanders ◽  
Ruilan Guo ◽  
Zachary P. Smith ◽  
Kevin A. Stevens ◽  
Qiang Liu ◽  
...  
Keyword(s):  
Functional Group ◽  
Gas Permeability ◽  
Ortho Position ◽  
Synthesis Route ◽  
Polymer Properties ◽  
Precursor Synthesis ◽  
Polyimide Precursor

Influence of polyimide precursor synthesis route and ortho-position functional group on thermally rearranged (TR) polymer properties: Conversion and free volume

Polymer ◽  
2014 ◽  
Vol 55 (7) ◽  
pp. 1636-1647 ◽  
Author(s):  
David F. Sanders ◽  
Ruilan Guo ◽  
Zachary P. Smith ◽  
Qiang Liu ◽  
Kevin A. Stevens ◽  
...  
Keyword(s):  
Free Volume ◽  
Functional Group ◽  
Ortho Position ◽  
Synthesis Route ◽  
Polymer Properties ◽  
Precursor Synthesis ◽  
Polyimide Precursor

Structural Characterization of a Series of New Ternary η-Nitride Compounds

1997 ◽  
Vol 495 ◽  
Author(s):  
K. S. Weil ◽  
P. N. Kumta
Keyword(s):  
Structural Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Synthesis Route ◽  
Precursor Synthesis ◽  
Structural Differences ◽  
Cubic Structure ◽  
Ternary Nitride

ABSTRACTThe structures of four new tungsten based, ternary nitride compounds, Fe3W3N, Ni6W6N, Ni2W4N, and Fe4W2N, each prepared using a complexed precursor synthesis route, have been determined by Rietveld analyses of the respective powder x-ray diffraction (PXRD) data. Each compound crystallizes in a relatively complex cubic structure which is in general isostructural with the η-carbide structure. However, subtle structural differences which are compositionally dependent do exist between each nitride and these will be examined in detail in this paper.

Exploration of Cation Substitution in the Layered Compound CrWN2

2002 ◽  
Vol 755 ◽  
Author(s):  
K. Scott Weil ◽  
Prashant N. Kumta ◽  
Jekabs Grins
Keyword(s):  
Phase Space ◽  
Layered Structure ◽  
Parent Phase ◽  
Layered Compound ◽  
Cation Substitution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Synthesis Route ◽  
Precursor Synthesis ◽  
And Tungsten

ABSTRACTA series of derivative compounds based on the layered parent phase CrWN2 have been synthesized using a complexed precursor synthesis route. X-ray diffraction analyses demonstrate that both the chromium and tungsten display mutual substitution for one another and can also undergo considerable extensive replacement by a wide variety of cation species without significantly altering the original layered structure of the parent dinitride compound. The precursor approach employed here appears to offer a ready technique for exploring compositional phase space in layered nitrides of this type.

scholarly journals Zinc-gallium oxynitride powders: effect of the oxide precursor synthesis route

Cerâmica ◽  
2013 ◽  
Vol 59 (350) ◽  
pp. 269-276 ◽  
Author(s):  
J. F. D. Figueiredo ◽  
V. Bouquet ◽  
S. Députier ◽  
O. Merdrignac-Conanec ◽  
I. Peron ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Synthesis Method ◽  
Synthesis Route ◽  
Surface Areas ◽  
Oxide Precursor ◽  
Precursor Synthesis ◽  
Final Compound ◽  
Nitridation Temperature

Zinc-gallium oxynitride powders (ZnGaON) were synthesized by nitridation of ZnGa2O4 oxide precursor obtained by polymeric precursors (PP) and solid state reaction (SSR) methods and the influence of the synthesis route of ZnGa2O4 on the final compound ZnGaON was investigated. Crystalline single phase ZnGa2O4 was obtained at 1100 ºC / 12 h by SSR and at 600 ºC / 2 h by PP with different grain sizes and specific surface areas according to the synthesis route. After nitridation, ZnGaON oxynitrides with a GaN würtzite-type structure were obtained in both cases, however at lower temperatures for PP samples. The microstructure and the specific surface area were strongly dependent on the oxide synthesis method and on the nitridation temperature (42 m²g-1 and 5 m²g-1 for PP and SSR oxides treated at 700 °C, respectively). The composition analyses showed a strong loss of Zn for the PP samples, favored by the increase of ammonolysis temperature and by the higher specific surface area.

Carboxylic Elastomers

1957 ◽  
Vol 30 (5) ◽  
pp. 1347-1386 ◽  
Author(s):  
H. P. Brown
Keyword(s):  
Functional Group ◽  
Polymer Chains ◽  
Carboxyl Groups ◽  
Polar Groups ◽  
Polymer Properties ◽  
Hydrocarbon Chains ◽  
Hydrocarbon Polymers ◽  
Polymer Strength ◽  
Increased Strength ◽  
Polymer Interaction

Abstract The degree to which a polymer is rubbery is influenced by the detailed shape and chemical composition of the macromolecules. Polymers which are rubbery possess relatively weak interchain forces and may lack linear symmetry and orderly arrangement of the molecule. As stronger interchain forces are added and symmetry and regularity are increased, the rubbery characteristics are gradually supplanted by those of fiber forming materials. Copolymerization with hydrocarbon chains may be used to reduce polymer to polymer interaction, destroy regularity and symmetry and favor rubbery characteristics. On the other hand it may be employed to introduce polar groups into hydrocarbon polymers and thereby increase interchain and intrachain forces. With increasing amounts of these polar groups polymer strength increases at the expense of elasticity with respect to both speed and range of extension and recovery. The polar groups also alter the solvent resistance of the polymer. In copolymerizations, carboxylic monomers tend to destroy regularity and symmetry thereby favoring rubbery properties over crystallinity. The strong polar nature of the carboxyl groups however increases interchain and intrachain forces imparting increased strength to the polymer at the expense of elasticity. Carboxyl groups were first introduced into rubbers for the purpose of altering polymer properties. When carboxyl groups are so employed, the resultant carboxylic rubbers are best regarded as polar elastomers. Carboxyl groups have also been introduced into rubbers in order that reactions characteristic of the carboxylic functional group might be employed to crosslink the polymer chains or attach them to other molecules or surfaces. When the carboxyl group is present in order that its functional reactivities may be employed, the carboxylic rubbers are best regarded as functional elastomers. This review is concerned with the preparation, properties and evaluation of carboxylic rubbers both as polar and as functional elastomers.

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