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Kathmandu, Nepal

Le H.H.,Martin Luther University of Halle Wittenberg | Hoang X.T.,Ho Chi Minh City University of Technology | Das A.,Leibniz Institute of Polymer Research | Gohs U.,Leibniz Institute of Polymer Research | And 7 more authors.
Carbon | Year: 2012

The effects of the surface modification of multi-walled carbon nanotubes (MWCNTs) by an ionic liquid, 1-butyl 3-methyl imidazolium bis(trifluoromethyl- sulphonyl)imide (BMI) on the kinetics of filler wetting and dispersion as well as resulting electrical conductivity of polychloroprene (CR) composites were studied. Two different MWCNTs were used, Baytubes and Nanocyl, which differ in their structure, purity and compatibility to CR and BMI. The results showed that BMI can significantly improve the macrodispersion of Baytubes, and increases the electrical conductivity of the uncured BMI-Baytube/CR composites up to five orders of magnitude. In contrast, the use of BMI slows the dispersion process and the development of conductivity of BMI-Nanocyl/CR composites. Our wetting concept was further developed for the quantification of the bound polymer on the CNT surface. We found that the bonded BMI on the CNT surface is replaced by the CR molecules during mixing as a result of the concentration compensation effect. The de- and re-agglomeration processes of CNTs taking place during the subsequent curing process can increase or decrease the electrical conductivity significantly. The extent of the conductivity changes is strongly determined by the composition of the bound polymer and the curing technique used. © 2012 Elsevier Ltd. All rights reserved. Source

Adhikari R.,Tribhuvan University | Adhikari R.,Nepal Polymer Institute NPI | Khatiwada S.P.,Tribhuvan University | Yadav A.P.,Tribhuvan University | Lebek W.,Martin Luther University of Halle Wittenberg
Macromolecular Symposia | Year: 2012

Conducting polymer films were prepared by introducing ionic groups via chemical modification of one of the blocks of the polystyrene-block- polybutadiene-block-polystyrene (SBS) triblock copolymer and by adding different amount of metal salts into the modified block copolymer. The butadiene part of the copolymer was partially sulphonated to prepare the proton conducting film while the epoxidized form was used to fabricate electron conducting films with different inorganic salts. The products were characterized by Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM) and potential as well as conductivity measurements. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Bhandari N.L.,Tribhuvan University | Bhandari N.L.,Nepal Polymer Institute NPI | Mormann W.,University of Siegen | Michler G.H.,Martin Luther University of Halle Wittenberg | And 2 more authors.
Materials Research Innovations | Year: 2013

The aim of this work is to study the morphological changes after alkali treatment and functionalisation of cellulosic materials present in crude bamboo and sisal flours using ionic liquid as solvents. The flours of bamboo (BF) and sisal (SF) were subjected to acetylation and silylation using acetic anhydride (AA) and hexamethyldisilazane (HMDS) as reagents. The changes in fibres structure and morphology were studied by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) respectively. The results indicate that crude BF and SF are functionalised successfully which is confirmed by FTIR spectra and the solubility of the derivatives in different solvents. The microscopic structures of the cellulose microfibre bundles become more distinct after delignification. © W. S. Maney & Son Ltd. 2013. Source

Pradhan S.,Tribhuvan University | Pradhan S.,Nepal Polymer Institute NPI | Scholtissek S.,Martin Luther University of Halle Wittenberg | Ghimire A.,Tribhuvan University | And 6 more authors.
Macromolecular Symposia | Year: 2013

A new type of ionomeric nanocomposite based on elastomeric ethylene/1-octene copolymer (EOC) and organophilically modified layered silicate was synthesized through sulfonation of the EOC followed by solution casting. The morphology-mechanical properties correlation of the product was studied with the help of scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy and recording microindentation measurement. The nanocomposite with uniformly distributed filler morphology could be conveniently prepared. It was found that the Martens hardness of ionomer nanocomposite comprising 5 wt.-% layered silicate is approximately threefold of the neat elastomer. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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