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Dhanalakshmi J.P.,k-Technology | Alam S.,Defence Materials and Stores Research and Development Establishment DMSRDE | Vijayakumar C.T.,k-Technology
High Performance Polymers | Year: 2013

The compound bispropargyl ether of bisphenol-A (BPEBPA) is prepared using phase transfer catalyst. Different copper salts like cuprous chloride (CuCl), cupric chloride dihydrate (CuCl2.2H2O), copper sulphate pentahydrate (CuSO4.5H2O), basic copper carbonate (CuCO3.Cu(OH) 2), cupric acetate monohydrate ((CH3COO)2Cu.H2O), and cupric oxide (CuO) are blended separately with BPEBPA (1%, w/w) and the curing characteristics of these materials are investigated using differential scanning calorimetry (DSC). The presence of copper salt in BPEBPA shifts the curing temperature to a lower temperature region. The materials are thermally cured and the structural characterisation and the thermal properties of these cross-linked materials are investigated using Fourier-transform infrared (FTIR) spectrophotometer and thermogravimetric analyzer (TGA). Of the different copper salts investigated, the presence of copper sulphate pentahydrate in BPEBPA increases the thermal stability of the cured BPEBPA. The thermal degradation products of thermally cured pure BPEBPA and copper salts containing BPEBPA are studied using TG-FTIR. The phenols, substituted phenols, carbon monoxide (CO), carbon dioxide (CO2), and alkenes are major volatiles evolved during the thermal degradation of these materials. © The Author(s) 2012.


Vijayakumar C.T.,k-Technology | Surender R.,k-Technology | Rajakumar K.,k-Technology | Alam S.,Defence Materials and Stores Research and Development Establishment DMSRDE
Journal of Thermal Analysis and Calorimetry | Year: 2011

The compound 2,2-bis[4-(4-maleimidophenoxy phenyl)]propane was prepared by the imidization of bisamic acid of 2,2-bis(4-aminophenoxy phenyl)propane. Various nanoclays were blended with this bismaleimide and thermally cured. The structural characterization of the synthesized materials and the thermal properties of the bismaleimide and their blends were investigated through FTIR, 1H and 13C NMR, differential scanning calorimetry and thermo gravimetric analysis. Among the various clays investigated, Cloisite 15A shows strong influence on the cure exotherm of bismaleimide. Introduction of clay mineral into bismaleimide shifts the onset of curing exotherm to higher temperature and is nearly 40 °C. The thermal stability of the clay loaded cured bismaleimide increases and the presence of clay particles in the cured bismaleimide matrix enhances the char formation. © 2010 Akadémiai Kiadó, Budapest, Hungary.


Katiyar R.,H+ Technology | Bag D.S.,Defence Materials and Stores Research and Development Establishment DMSRDE | Nigam I.,H+ Technology
International Journal of Chemical Kinetics | Year: 2011

Radical copolymerization of fullerene (C60) and n-butyl methacrylate (BMA) has been carried out using triphenylbismuthonium ylide as an initiator at 70°C for 4 h in a dilatometer under nitrogen atmosphere. The kinetic expression of the polymerization is Rpα [Ylide] 0.5[C60]-1.0[BMA]1.2, which is similar to that expected for ideal kinetics. The rate of polymerization increases with an increase in the concentration of initiator and BMA. However, it decreases with an increase in the concentration of fullerene. Fullerene acts as radical scavengers causing retardation in polymerization. The activation energy of copolymerization was estimated to be 72.2 K J mol-1. The fullerene-containing BMA copolymers were characterized by FTIR, 1H NMR, 13C NMR, UV-vis, and GPC analyses. © 2011 Wiley Periodicals, Inc.


Katiyar R.,H+ Technology | Bag D.S.,Defence Materials and Stores Research and Development Establishment DMSRDE | Nigam I.,H+ Technology
Thermochimica Acta | Year: 2013

In this investigation, thermal properties of fullerene (C60) containing poly(alkyl methacrylate)s have been studied. The glass transition temperatures (Tg) and thermal stability of C60 containing poly(methyl methacrylate) (FMMA) and poly(n-butyl methacrylate) (FBMA) were more than that of the corresponding virgin polymers and the values increased with the increasing fullerene content in such polymers. Chemically linked bulky fullerene imparts chain rigidity and hence restricts segmental motion causing higher Tg values for C60 containing polymers than that of the polymers without fullerene. Thermal degradation of C60 containing poly(alkyl methacrylate)s is hindered prominently due to the presence of fullerene which scavenges the macroradicals formed during polymer degradation. The mechanism of thermal degradation of C60 containing poly(alkyl methacrylate)s is, therefore, associated mainly with three types of reactions: (a) end chain scission, (b) random chain scission and (c) reaction of fullerene (C60) with macroradicals obtained in thermal degradation process. © 2013 Elsevier B.V.


Mandal S.,Defence Materials and Stores Research and Development Establishment DMSRDE | Alam S.,Defence Materials and Stores Research and Development Establishment DMSRDE
Materials Research Innovations | Year: 2013

In the present study, the mechanical and thermal properties of the nanocomposites of optimised poly(ether ether ketone) (PEEK) and poly(ether ketone) (PEK) blend incorporated with nano-barium titanate (nano-BT) were investigated. The optimised blend was based on the mechanical and thermal properties of PEEK and PEK in the ratio of 80:20. Nanoparticles were incorporated into the optimised blend with the help of a twin screw extruder. The concentration of nano-BT was varied from 2 to 6 wt-%. The crystallinity of the nanocomposites was calculated using differential scanning calorimetry method. With the increase in the nanosized BT concentrations, the tensile strength, tensile modulus and impact strength increased while the elongation at break and crystallinity decreased. The crystallinity of the nanocomposites influenced the elongation at break. Morphological studies were carried out using SEM. The nanocomposites were evaluated using the theoretical predictive model known as 'Pukanszky model' applicable to the tensile strength of the nanocomposites. © 2013 W. S. Maney & Son Ltd.

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