Showing papers by "Dipak Khastgir published in 2011"
TL;DR: In this article, conductivity and EMI SE of conductive composites were measured in the X band frequency range 8-12 GHz in the presence of two different types of fillers (Conductex and printex XE2).
Abstract: The conductive composites were prepared using two different types of conductive black (Conductex and Printex XE2) filled in matrices like EVA and NBR and their different blends. The electromagnetic interference shielding effectiveness (EMI SE) of all composites was measured in the X band frequency range 8–12 GHz. Both conductivity and EMI SE increase with filler loading. However, Printex black shows higher conductivity and better EMI SE at the same loading compared to Conductex black, and this can be used as a material having high EMI shielding effectiveness value. The conductivity of different blends with same filler loading generally found to increase slightly with the increase in NBR concentration. However, EMI SE has some dependency on blend composition. EMI SE increases linearly with thickness of the sample. EMI SE versus conductivity yields two master curves for two different fillers. EMI SE depends on formation of closed packed conductive network in insulating matrix, and Printex black is better than Conductex black in this respect. Some of the composites show appreciably high EMI SE (>45 dB).
158 citations
TL;DR: In this paper, the applicability of different theoretical models to predict the conductivity of conductive composites was verified, and a modified model was proposed, which exhibited better agreement between theoretical and experimental conductivities over wide range of concentrations for all three fillers.
97 citations
TL;DR: In this article, the dielectric property and electromagnetic interference shielding of carbon black, short carbon fiber (SCF), and multiwall carbon nano-tube (MWNT)-filled conductive composites were studied with different filler loadings.
Abstract: Carbon black, short carbon fiber (SCF), and multiwall carbon nano-tube (MWNT)-filled conductive composites were prepared from ethylene vinyl acetate copolymer. The dielectric property and electromagnetic interference (EMI) shielding of carbon black, MWNT, and SCF-filled composites were studied with different filler loadings. The dielectric constant and loss of filled polymer composites is due to the formation of interfacial polarization in the polymer matrix. It was found that the dielectric constant, dielectric loss, and EMI shielding of filled composites depends on amount and type of filler loading. The results of different experiments have been discussed in the light of break down and formation of continuous conductive network in polymer matrix. The results indicate that these composites can be used as effective EMI shielding materials. POLYM. COMPOS., 32:1148–1154, 2011. a 2011 Society of Plastics Engineers
87 citations
TL;DR: In this article, the authors have shown that the necking phenomenon is increasing with the increase in fiber concentration in the polymer matrix, which is explained on the basis of percolation theory.
Abstract: The composites of carbon fiber with EVA, NBR, and their blends have been made by melt mixing technique. Stress–strain plots of different composites show that the necking phenomenon is increasing with the increase in fiber concentration in the polymer matrix. The scanning electron microscopic analysis and swelling study exhibit poor interaction between the short carbon fiber and polymer matrix. The decrease in DC resistivity with the increase in short carbon fiber concentration has been explained on the basis of percolation theory. EMI SE increases slightly with the increase in frequency of electromagnetic radiation but increases sharply with the increase in fiber concentration. EMI SE also depends on blend composition and increases with the increase in EVA concentration in the blend. Return loss is decreasing but absorption loss is increasing with the increase in fiber loading. A linear relationship is observed between the EMI SE and thickness of the composites. The EMI SE is found to increase exponentially with the increase in conductivity of the composite. The permeability value is decreasing with the increase in frequency as well as fiber loading. Thermal properties of the composites have been evaluated by thermogravimetric analysis and dynamic mechanical analysis. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
62 citations
TL;DR: In this paper, thermal properties of carbon nanotubes-reinforced polysulfone (PSU) nanocomposites were characterized using TGA and differential scanning calorimetry (DSC).
Abstract: Carbon nanotubes (CNTs)-reinforced polysulfone (PSU) nanocomposites were prepared through solution mixing of PSU and different weight percent of multi-walled carbon nanotubes (MWCNTs). Thermal properties of nanocomposites were characterized using thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA studies revealed an increase in thermal stability of the PSU/MWCNTs nanocomposites, which is due to the hindrance of the nanodispered carbon nanotubes to the thermal transfer in nanocomposites and also due to higher thermal stability of CNTs. Morphological properties of nanocomposites were characterized by high resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscope (FESEM). The influence of CNTs loading on electrical properties of PSU/MWCNTs nanocomposites was studied by the measurement of AC and DC resistivity. Dielectric study of nanocomposites was carried out at different frequencies (10 Hz–1 MHz) by using LCR meter. An increase in dielectric constant and dielectric loss was observed with increase in CNTs content, which is due to the interfacial polarization between conducting CNTs and PSU.
55 citations
TL;DR: In this article, polyaniline (PAni) was synthesized by miniemulsion polymerization and applied on cast iron and stainless steel coupons using spin coating technique to resist mold/ fungal growth.
Abstract: Polyaniline (PAni) was synthesized by miniemulsion polymerization. One coating solution of poly (epichlorohydrine-co-ethylene oxide) (ECO) and another of ECO and PAni mixture were prepared in a mixture of solvents and then applied on cast iron and stainless steel coupons using spin coating technique. The efficiency of these coatings to retard the environmental rust formation was studied as per the ASTM D610-01 and the rate of corrosion was determined electrochemically using a potentiostat/ galvanostat. The efficiency of these two coatings to resist the mold/ fungal growth was estimated as per the ASTM D5590-00. The results revealed that the PAni can retard the corrosion to a great extent by accelerating the formation of a passive Fe2O3 layer on the cast iron and stainless steel surfaces. PAni also has the ability to impede the mold growth by escalating the release of chlorine dioxide (ClO2).
Key words: Corrosion, polyaniline, iron, stainless steel, SEM.
11 citations