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Full-Text Articles in Nanoscience and Nanotechnology

Structure And Properties Of Polypropylene-Nanoclay Composites, Raghavendra R. Hegde Dr Nov 2013

Structure And Properties Of Polypropylene-Nanoclay Composites, Raghavendra R. Hegde Dr

Raghavendra R Hegde Dr

The structure, morphology and mechanical properties of polypropylene-nanoclay composites with 1 to 15 wt.% nanoclay additives were investigated. Mixture of intercalated and exfoliated morphology was observed in nanocomposites. At higher weight percentage reinforcement (10–15 wt.%), up to 67 % improvement in tensile modulus is observed. At higher weight percentage, exclusion of clay additives at the boundary of spherulites was observed. This study illustrates that along with the thermodynamic driving force, spherulite formation also drives the ultimate morphology


Investigation Of The Morphology Of Polypropylene-Nanoclay Nanocomposites, Raghavendra R. Hegde Dr Sep 2013

Investigation Of The Morphology Of Polypropylene-Nanoclay Nanocomposites, Raghavendra R. Hegde Dr

Raghavendra R Hegde Dr

The morphology development in polypropylene − nanoclay composites with different weight percentages of nanoclay additives was studied using a combination of wide-angle X-ray diffraction, small-angle X-ray scattering (SAXS), polarized optical microscopy and transmission electron microscopy. SAXS studies showed an increase in long period with increase in additive weight percentage. Thermal analysis showed that even if the clay platelets are not completely exfoliated they can act as effective nucleating agents. Studies indicated that the ultimate morphology formation is influenced by both the thermodynamics of mixing and crystallization and spherulite formation. During spherulite growth, unenclosed clay platelets were excluded at the spherulite …


The Impact Of Controlled Solvent Exposure On The Morphology, Structure And Function Of Bulk Heterojunction Solar Cells, Raghavendra R. Hegde Dr Dec 2012

The Impact Of Controlled Solvent Exposure On The Morphology, Structure And Function Of Bulk Heterojunction Solar Cells, Raghavendra R. Hegde Dr

Raghavendra R Hegde Dr

Films of poly(3-hexyl thiophene) (P3HT):[6,6]-phenyl C61-butyric acid methyl ester (PCBM) were controllably exposed to CS2 vapor in a column with a linear solvent vapor pressure gradient. Changes in the morphology of the P3HT:PCBM thin film were monitored and correlated to the ability of this thin film to act as the active layer in an organic solar cell. The results show that the crystallinity and crystal size of the P3HT increase initially with solvent vapor pressure and annealing time, but longer exposure to solvent decreases P3HT crystallinity and photovoltaic efficiency. Neutron reflectivity indicates that the PCBM segregates to the Si substrate …


The Miscibility And Depth Profile Of Pcbm In P3ht: Thermodynamic Information To Improve Organic Photovoltaics, Raghavendra R. Hegde Dr Apr 2012

The Miscibility And Depth Profile Of Pcbm In P3ht: Thermodynamic Information To Improve Organic Photovoltaics, Raghavendra R. Hegde Dr

Raghavendra R Hegde Dr

Recent work has shown that poly(3-hexylthiophene) (P3HT) and the surface-functionalized fullerene 1-(3-methyloxycarbonyl)propyl(1-phenyl[6,6])C(61) (PCBM) are much more miscible than originally thought, and the evidence of this miscibility requires a return to understanding the optimal morphology and structure of organic photovoltaic active layers. This manuscript describes the results of experiments that were designed to provide quantitative thermodynamic information on the miscibility, interdiffusion, and depth profile of P3HT : PCBM thin films that are formed by thermally annealing initial bilayers. It is found that the resultant thin films consist of a 'bulk' layer that is not influenced by the air or substrate surface. …


Nanoclay Reinforced Fibers And Nonwovens, Raghavendra R. Hegde Dr Jan 2008

Nanoclay Reinforced Fibers And Nonwovens, Raghavendra R. Hegde Dr

Raghavendra R Hegde Dr

In this research, polypropylene fibers and nonwoven samples were produced with the commercial samples of nanoclay additives in semi-commercial processing machinery. Influence of two different types of nanoclay additives, at different add on levels on processing, structure and morphology of nonwovens is studied. The WAXD and DSC data showed some change in crystallinity and melting behavior indicating changes in the fiber morphology towards improved mechanical properties. Presence and extent of exfoliation of nanoclay in the polymer was verified using transmission electron microscopy (TEM). TEM image reveals intercalated and exfoliated morphology of nanocomposites. About 10 to 20 % increase in tensile …