@article { ISI:000244413600017, title = {Spinning wave motion in frontal polymerization}, journal = {Chemical Engineering Science}, volume = {62}, number = {5}, year = {2007}, month = {MAR}, pages = {1448-1455}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

We present a mathematical model describing dynamics of spinning waves which propagate during frontal polymerization reaction taking place in a cylindrical reactor tube. The self-organization of spatio-temporal solution of wave equations due to interplay between thermal diffusion and kinetics gives rise to pattern formation. We begin with a fundamental equation of motion of radial coordinate after defining an asymptotic phase for spinmode. The motion is analyzed near a critical (Hopf) point and a perturbation solution is used to obtain patterns for a case of preparation of poly(2-hydroxyethyl methacrylate) (PHEMA) via frontal polymerization reaction. The model uses the distance as seen in photograph taken using scanning electron microscope (SEM) from which motion begins around core of spiral and calculates pitch of spiral which matches closely with experimental observation in micrograph. Also the model predicts qualitatively the ramp wave and spiral wave motion as observed under SEM. Both these results are reported in open literature for the first time to our best knowledge. (c) 2006 Elsevier Ltd. All rights reserved.

}, keywords = {frontal polymerization, spinning wave, spiral motion, wave dynamics}, issn = {0009-2509}, doi = {10.1016/j.ces.2006.11.037}, author = {Inamdar, Satish R. and Pujari, N. S. and Karimi, I. A. and Ponrathnam, S. and Tayal, R. K. and Kulkarni, B. D.} } @article { ISI:000286633000031, title = {Synthesis and photopolymerization kinetics of linear alicyclic urethane acrylate macromonomer in presence of reactive diluents}, journal = {Journal of Materials Science}, volume = {46}, number = {7}, year = {2011}, month = {APR}, pages = {2221-2228}, publisher = {SPRINGER}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

This study deals with the photopolymerization of a macromonomer in the presence of reactive diluents using Photo Differential Scanning Calorimetry or Photo DSC. The kinetic profiles of these systems showed that the rate of photopolymerization rapidly increases at very early stages of the reaction. The rate of reaction was further found to increase with the addition of crosslinking agents. The addition of trifunctional crosslinking agent to the macromonomeric formulation resulted in a higher polymerization rate and conversion than that of a difunctional crosslinking agent. From the heat flow profiles, the kinetic parameters such as induction time, time to attain peak maximum, rate of maximum polymerization, and final conversion were noted for all the formulations. The initiation of photopolymerization was found to depend on the functionality while the in situ viscosity controlled the time scale for reaction diffusion which resulted in varying levels of conversions. Other parameters such as effect of temperature and concentration of photoinitiator on photocuring kinetics are also discussed.

}, issn = {0022-2461}, doi = {10.1007/s10853-010-5060-9}, author = {Harikrishna, Reghunathan and Bhosle, Sonali Madhavrao and Ponrathnam, S. and Rajan, C. R.} } @article { ISI:000350698600007, title = {Synthesis of novel silica-polyimide nanocomposite films using aromatic-amino modified silica nanoparticles: mechanical, thermal and morphological investigations}, journal = {Express Polymer Letters}, volume = {9}, number = {5}, year = {2015}, month = {MAY}, pages = {469-479}, publisher = {BUDAPEST UNIV TECHNOL \& ECON}, address = {DEPT POLYMER ENG, MUEGYETEM RKP 3, BUDAPEST, H-1111, HUNGARY}, abstract = {

Silica nanoparticles were modified with aromatic amino groups and modified-silica/polyimide composite films were prepared using them. 3,3!, 4,4!-Benzophenone tetracarboxylic dianhydride (BTDA) and 4,4!-oxydianiline (ODA) were used as precursors for polyimide matrix. The structures of the modified nanoparticles and hybrid nanocomposites were identified using Fourier Transform Infrared (FTIR) spectrometry. The hybrid composite films were evaluated for mechanical, thermal and morphological characteristics. Morphological results describe a uniform dispersion of silica particles in the polymer matrix. The thermal stability and mechanical properties of polyimide composite were improved, and the decomposition temperature was increased when the amount of silica nanoparticles was increased.

}, keywords = {hybrid polyimide composites, mechanical properties, Nanocomposites, nanoparticle modification, Thermal properties}, issn = {1788-618X}, doi = {10.3144/expresspolymlett.2015.44}, author = {Ghorpade, Ravindra V. and Rajan, C. R. and Chavan, Nayaku and Ponrathnam, S.} } @article { ISI:000370420000003, title = {Synthesis and characterization of thermally stable polyimides with a pendent phenothiazine unit based on new diamine 10-(3,5-diaminobenzoyl)phenothiazine}, journal = {High Performance Polymers}, volume = {28}, number = {1}, year = {2016}, month = {FEB}, pages = {26-33}, publisher = {SAGE PUBLICATIONS LTD}, address = {1 OLIVERS YARD, 55 CITY ROAD, LONDON EC1Y 1SP, ENGLAND}, abstract = {

A novel diamine 10-(3,5-diaminobenzoyl)phenothiazine (DBPT) with a side chain containing phenothiazine unit was synthesized. A new family of polyimides (PIs) containing phenothiazine unit in the side chains has been successfully synthesized by direct polycondensation of DBPT with pyromellitic dianhydride, 3,3{\textquoteright},4,4{\textquoteright}-benzophenone tertacarboxylic dianhydride, and 4,4{\textquoteright}-oxydiphthalic anhydride (ODA) via a conventional two-step chemical imidization process. The yield of polymers was good enough, which were soluble in most organic solvents. The molecular orbital energy gaps, thermal stability, and crystallinity of PIs were investigated by molecular modeling, thermogravimetric analysis, and wide-angle X-ray scattering, respectively. Thermal properties of polymers were good enough to permit the use of these PIs in various applications; only 49\% weight loss is detected at 900 degrees C in nitrogen atmosphere. X-Ray diffraction clearly reveals the amorphous nature of PIs. A quantum modeling study (density functional theory) has shown the influence of dianhydride structure on the energy difference of highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels.

}, keywords = {phenothiazine-containing diamine, Polyimide, thermally stable polymer}, issn = {0954-0083}, doi = {10.1177/0954008314568877}, author = {Ghorpade, Ravindra V. and Thorave, Asmita K. and Rajan, C. R. and Chavan, Nayaku and Ponrathnam, S.} }