Showing papers by "Anjanapura V. Raghu published in 2008"
TL;DR: In this paper, a nanocomposite of waterborne polyurethane (WPU) was prepared with functionalized graphene sheets (FGSs), which are a new type of nano-sized conductive filler.
Abstract: A nanocomposite of waterborne polyurethane (WPU) was prepared with functionalized graphene sheets (FGSs) which are a new type of nano-sized conductive filler. The FGS were finely dispersed in a polymer matrix to improve the conductivity of the WPU. Conductivity of about 105 times that of pristine WPU was attained using two parts FGS per 100 parts of the matrix polymer. The FGS reduced the hard segment crystallinity of the WPU, which lowered the modulus of the WPU at room temperature. This modulus reduction became more evident in the temperature region above the glass transition temperature of the hard segment.
231 citations
TL;DR: A series of segmented polyurethanes (PUs) containing imine units in the main chain were prepared by polyaddition reaction of various diisocyanates as discussed by the authors.
Abstract: A series of novel segmented polyurethanes (PUs) containing imine units in the main chain were prepared
by polyaddition reaction of various diisocyanates like 4,4’-diphenyl-methane diisocyanate, tolylene 2,4-diisocyanate,
isophorone diisocyanate and hexamethylene diisocyanate with 4,4’-{1,4-phenylenebis[methylylidenenitrilo]}
diphenol based diol. The structure of the diol and segmented PUs were determined by Fourier transform infrared,
ultraviolet-visible spectrometry and fluoroscence spectroscopy. PUs were soluble is polar aprotic solvents.
Thermal properties were done by using differential scanning calorimetry (DSC) and thermogravimetric analysis.
DSC data display the PUs having multiple endotherm peaks. MDI based PU show the more thermal stable compared
to other PUs.
90 citations
TL;DR: In this paper, the synthesis and characterization of novel polyurethanes (PUs) by the reaction between two aromatic diisocyanates (4,4′-diphenylmethane diisocalate and tolylene 2,4-diisocynate) with N1,N4-bis[(4-hydroxyphenyl)methylene]succinohydrazide, which acted as hard segment.
Abstract: This article deals with the synthesis and characterization of novel polyurethanes (PUs) by the reaction between two aromatic diisocyanates (4,4′-diphenylmethane diisocyanate and tolylene 2,4-diisocyanate) and two aliphatic diisocyanates (isophorone diisocyanate and hexamethylene diisocyanate) with N1,N4-bis[(4-hydroxyphenyl)methylene]succinohydrazide, which acted as hard segment. UV–vis, FTIR, 1H NMR, 13C NMR, and DSC/TGA analytical technique has been used to determine the structural characterization and thermal properties of the hard segmented PUs. X-ray diffraction revealed that PUs contained semicrystalline and amorphous regions that varied depending upon the nature of the backbone structures. PUs were soluble in polar aprotic solvents. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
61 citations
TL;DR: In this article, four novel types of polyurethanes (PUs) were prepared from N1,N2-bis[(4-hydroxyphenyl)methylene]ethanedihydrazide with two aromatic diisocyanates (4,4′-diphenylmethane diisOCD) and tolylene 2,4-diisocynate) and two aliphatic diisodicyanates, and the chemical structure of both diol and PUs were confirmed by UV-vis, fluor
Abstract: Four novel types of polyurethanes (PUs) were prepared from N1,N2-bis[(4-hydroxyphenyl)methylene]ethanedihydrazide with two aromatic diisocyanates (4,4′-diphenylmethane diisocyanate and tolylene 2,4-diisocyanate) and two aliphatic diisocyanates (isophorone diisocyanate and hexamethylene diisocyanate). The chemical structure of both diol and PUs was confirmed by UV–vis, fluoroscence, FTIR, 1H NMR, and 13C NMR spectral data. DSC data show that PUs have multiple endotherm peak. X-ray diffraction revealed that the PUs contained semicrystalline and amorphous regions that varied with the nature of the backbone structures. PUs were soluble in polar aprotic solvents. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
55 citations
TL;DR: In this paper, four novel polyurethanes were prepared from 4-{(4-hydroxyphenyl)iminomethyl}phenol by reactions with two aromatic diisocyanates, 4,4′-diphenylmethane diiscyanate and toluene 2,4-diisocynate, and two aliphatic diiscynate.
Abstract: Four novel polyurethanes were prepared from 4-{(4-hydroxyphenyl)iminomethyl}phenol by reactions with two aromatic diisocyanates, 4,4′-diphenylmethane diisocyanate and toluene 2,4-diisocyanate, and two aliphatic diisocyanates, isophorone diisocyanate and hexamethylene diisocyanate. The polyurethanes formed were characterized by UV-vis, fluorescence, FT-IR,1H-NMR,13C-NMR, differential scanning calorimetry, thermogravimetry, and X-ray diffraction. The polymers were semi-crystalline and all polymers were soluble in polar aprotic solvents.
49 citations
TL;DR: Bhattacharya et al. as discussed by the authors predicted the blend incompatibility of poly(n-vinyl pyrrolidone) and poly(bi-sphenol-Aether sulfone) (PES).
Abstract: Molecular simulations are the most important tools to predict the properties of polymers and their blends. In this work, we have predicted the blend incompatibility of poly(n-vinyl pyrrolidone) (PVP) and poly(bi-sphenol-A-ether sulfone) (PES). Atomistic simulations were performed to compute the Flory-Higgins interaction parameter over all the compositions ranging from 90 to 10% of the individual polymers, which confirmed that the blends are incompatible (Bhattacharya et al., J Membr Sci 2003, 227, 23). Kinetics of phase separation was examined via density profiles calculated using MesoDyn approach. For incompatible blends, the critical value of 0.32 computed from the Flory-Huggins theory agreed with the value of 0.29, suggesting the validity of our approach.
42 citations