Lucky Krishnia; Reetu Kumari; Vinay Kumar; Anshika Singh; Preeti Garg; Brajesh S. Yadav; Pawan K. Tyagi
Abstract
Filled or un-filled multiwalled carbon nanotubes (CNTs) used in this study have been synthesized by the floating catalyst method and fixed catalyst method, respectively. The thermal stability of filled/un-filled carbon nanotubes has been investigated by using Thermogravimetric analysis (TGA) and Derivative ...
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Filled or un-filled multiwalled carbon nanotubes (CNTs) used in this study have been synthesized by the floating catalyst method and fixed catalyst method, respectively. The thermal stability of filled/un-filled carbon nanotubes has been investigated by using Thermogravimetric analysis (TGA) and Derivative thermogravimetric (DTG) analysis. In this report, we have developed a methodology to distinguish between filled and un-filled carbon nanotubes. Filled-CNTs are found to be more resistant to oxidation than the un-filled carbon nanotubes. The calculated activation energy of as-grown filled CNTs, by using differential method, determined to be 3.29 ± 0.04 eV, which is higher than that of highly ordered pyrolytic graphite (HOPG). Carboneous impurities; amorphous carbon, catalyst and CNT of different diameter, which are structurally different, are identified by their reactivity and the resistance to oxidation.
Susheel Kalia; Hemmant Mittal;Amit Kumar; Renu Sheoran
Abstract
Ramie fibers usually display poor interfacial adhesion when reinforced in hydrophobic polymer matrices. Hydrophilic nature of natural fibers becomes the most crucial issue in composites engineering. Surface modification of natural fibers has been found to be very effective in improving the fiber-matrix ...
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Ramie fibers usually display poor interfacial adhesion when reinforced in hydrophobic polymer matrices. Hydrophilic nature of natural fibers becomes the most crucial issue in composites engineering. Surface modification of natural fibers has been found to be very effective in improving the fiber-matrix adhesion. In the present paper, we have reported the microwave assisted grafting of binary vinyl monomer mixtures on to ramie fibers (Boehmeria nivea) and bacterial cellulase assisted pre-treatment of ramie fibers using bacteria Brevibacillus parabrevis. The effects of these pretreatments on some properties of ramie fibers are discussed in the present paper. The modified fibers were characterized by scanning electron microscopy (SEM), X-ray diffraction, and TGA/DTA techniques to determine their morphology, crystallinity and thermal stability. Surface of ramie fiber becomes rough on grafting with synthetic polymers, whereas biologically modified ramie fibers showed the enhanced softness and smooth appearance due to the removal of gum materials and other impurities from the surface of fibers. Both the treatments have slightly changed the thermal stability and crystallinity of ramie fibers.
J. Selvakumar; K. S. Nagaraja
Abstract
The thermal stability and suitability of synthesized yttrium metallorganic complexes were studied for chemical vapor deposition use by thermogravimetric analyses. The phase purity of the synthesized complexes was analyzed by powder X-ray diffraction and mass spectral techniques. The equilibrium vapor ...
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The thermal stability and suitability of synthesized yttrium metallorganic complexes were studied for chemical vapor deposition use by thermogravimetric analyses. The phase purity of the synthesized complexes was analyzed by powder X-ray diffraction and mass spectral techniques. The equilibrium vapor pressure of screened yttrium complexes was measured over a temperature range 319–475 K using the horizontal thermogravimetric analyzer as a transpiration apparatus. Model and model-free solid-state kinetic methods were applied to non-isothermal and isothermal measurements to derive kinetic characteristics of the sublimation/evaporation process of selected yttrium vapor sources in the conversion range of 0.1 < 0.7. The relevant results are discussed in detail.
Anjna Kumari; ;Susheel Kalia; Balbir Singh Kaith; Amar Singh Singha; and Susheel Kalia
Abstract
Psyllium, a medicinally important natural polymer was functionalized with acrylic acid using FAS-H2O2 as redox initiator and glutaraldehyde as a crosslinker. Synthesized hydrogel was characterized with FTIR spectroscopy, SEM and TGA/DTA techniques to know their surface morphology and thermal stability. ...
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Psyllium, a medicinally important natural polymer was functionalized with acrylic acid using FAS-H2O2 as redox initiator and glutaraldehyde as a crosslinker. Synthesized hydrogel was characterized with FTIR spectroscopy, SEM and TGA/DTA techniques to know their surface morphology and thermal stability. Salt resistant swelling behavior of synthesized hydrogel was studied in different salt solutions as a function of concentration of salt, temperature and pH. It was found that synthesized hydrogel showed maximum swelling (514.0 %) in NaCl solution followed by NH4Cl, MgCl2, CaCl2 and BaCl2 solution. Psy-g-poly(AA) hydrogel showed maximum swelling (863.49%) at 30 ºC in distilled water.
