Найдено научных статей и публикаций: 3, для научной тематики: XRD
1.
Muralidhar G. Chourashiya, Yong-Han Kim, Choong-Nyeon Park, Chan-Jin Park
- Journal of Alloys and Compounds , 2014
The present investigation evaluates the effect of milling the hydriding combustion synthesized (HCSed) MgNiC composite with NbF5 catalyst. X-ray analysis revealed that h-Mg-(1 0 1) peak positions of the ball-milled samples shifted by an amount that varied with the milling time. Morphologically, amon...
The present investigation evaluates the effect of milling the hydriding combustion synthesized (HCSed) MgNiC composite with NbF5 catalyst. X-ray analysis revealed that h-Mg-(1 0 1) peak positions of the ball-milled samples shifted by an amount that varied with the milling time. Morphologically, among the SPEX ball-milled samples the samples with the NbF5 catalyst showed slightly delayed refinement/agglomeration with milling time which was attributed to lubricating-behavior of NbF5 during milling. The final products from both (planetary and SPEX) ball mills showed insignificant agglomeration. A general trend of decreasing surface area with increasing milling time was observed. The HCSed sample manually mixed with catalyst showed the largest surface area of 23.78 m2/g. The presence of the catalyst and different interfaces, such as Mg–Nb, Mg–Ni and Mg–CNTs, in the samples played a crucial role in decreasing the thermal constraints for dehydrogenation. Analysis of hydrogenation kinetics revealed that the catalyst added samples requires activation and can be easily activated. By relating the hydrogenation kinetic data with the JMAK model, the value of the reaction order, n, was found to be close to 1 for all the samples, suggesting a possible diffusional phase transition. The lowest activation energy observed in synthesized sample for hydrogenation was 64.9 kJ/mol.
2.
K R Vishnu Mahesh1, H N Narasimha Murthy, B E Kumara Swamy, S C Sharma, R Sridhar, Niranjan Pattar, M Krishna, B S Sherigara
- Front. Mater. Sci. , 2011
This paper reports the dispersion of Montmorillonite nanoclay in vinylester using ultrasonication and co-rotating twin screw extrusion for preparing nanoclay/vinylester gel coat. Two sets MMT/vinylester specimens, namely Type 1 and Type 2 were prepared for comparative studies. While Type 1 specimens...
This paper reports the dispersion of Montmorillonite nanoclay in vinylester using ultrasonication and co-rotating twin screw extrusion for preparing nanoclay/vinylester gel coat. Two sets MMT/vinylester specimens, namely Type 1 and Type 2 were prepared for comparative studies. While Type 1 specimens were prepared using ultrasonication only, Type 2 specimens were prepared using both ultrasonication and twin screw extrusion. Dispersion of nanoclay in vinylester was studied using XRD and TEM. Type 2 specimens showed lower levels of nanoclay agglomeration and higher levels of exfoliation. DSC results showed that glass transition temperature in Type 2 specimens is better than that of Type 1 specimens. The TGA results showed that the residual weight in 4 wt % MMT/vinylester of Type 1 was 7.38 % and the corresponding value for Type 2 was 13.5 %, indicating lower thermal degradation in the latter. By using the MMT/vinylester gel coat so prepared by the two different routes, MMT/vinylester/glass and MMT/vinylester/carbon specimens were fabricated and tested for mechanical and fire retardation behaviour. Type 2 based nanocomposite laminates showed greater values of ultimate tensile strength, flexural strength, interlaminar shear strength, impact strength, Horizontal burning rate, and Vertical burning rate than that of Type 1 based laminates. Scanning Electron Micrographs of tensile fractured Type 2 based laminates showed no or less agglomeration of nanoclay than that of Type 1 based laminates
3.
K. R. Vishnu Mahesh, H. N.Narasimha Murthy, B.E. Kumara Swamy, M. Krishna, and B.S. Sherigara
- Front. Chem. China , 2011
The Sodium Montmorillonite (Na-MMT) is not susceptible to polymer due to its organophilic character and low basal spacing. The primary objective of this study was to improve Na-MMT platelets separation by organically modifying it with cation and anion exchanges using Cetyl trimethyl ammonium bromide...
The Sodium Montmorillonite (Na-MMT) is not susceptible to polymer due to its organophilic character and low basal spacing. The primary objective of this study was to improve Na-MMT platelets separation by organically modifying it with cation and anion exchanges using Cetyl trimethyl ammonium bromide (CTAB) and Sodium dodecyl sulfate (SDS) respectively.
Basal spacing, presence of functional groups, Zetapotential
with particle size analysis and thermal
stability of the Organomodified Na-MMT (OMMT)
were characterized using XRD, FTIR, zeta-potential
analyzer and TGA respectively. The basal spacing of
CTAB modified OMMTincreased to 19.5 Å from 11.0 Å
which corresponds to the basal spacing of Na-MMT.
The SDS modified OMMT did not show any increase in
the basal spacing. FTIR spectra of CTAB modified Na-
MMT illustrated the attachment of CTAB functional
groups to Na-MMT, while the same was absent in the
case of SDS modified Na-MMT. The zeta-potential of
Na-MMT shifted from – 24.88 mV to 15.66 mV in the
case of CTAB modified Na-MMTand 12.49 mV for SDS
modified Na-MMT, indicating a greater surface potential of the modified nanoclay. The TGA showed greater weight loss for CTAB modified Na-MMT than that for Na-MMT, indicating the effective Na+ ion exchange with alkyl amines.