@article { ISI:000232341100010, title = {Photodegradation of ethylene/propylene/polar monomers co- and terpolymers. I - Prepared by group 4 catalyst systems}, journal = {Journal of Macromolecular Science-Pure and Applied Chemistry}, volume = {A42}, number = {9}, year = {2005}, month = {SEP}, pages = {1259-1270}, publisher = {TAYLOR \& FRANCIS INC}, type = {Article}, address = {325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USA}, abstract = {

The photooxidative degradation behavior of polyethylene, its copolymers (propylene/polar monomers) and terpolymers, synthesized by a group 4 catalyst system, has been studied by Fourier transform infrared spectroscopy and confirmed with scanning elecrton microscopy for morphological changes. The kinetics of photodegradation has also been studied. Surface damage caused by polychromatic (\>= 290 nm) at 55 degrees C in air is presented in different micrographs. The rate of photodegradation is very fast in terpolymers containing polar monomers as compared with copolymers and polyethylene. Morphological study of these photodegraded samples showed a very good relation with photodegradation results.

}, keywords = {functional polyolefins, Photodegradation, UV irradiation}, issn = {1060-1325}, doi = {10.1080/10601320500189570}, author = {Fernandes, Susete N. and Correia, Sandra and Prasad, A. V. and Reddy, K. R. and Rana, S. and Lonkar, Sunil P. and Marques, Maria M. and Singh, R. P.} } @article { ISI:000251014000004, title = {Photo-stabilization of EPDM-clay nanocomposites: effect of antioxidant on the preparation and durability}, journal = {Polymers for Advanced Technologies}, volume = {18}, number = {11}, year = {2007}, note = {International Conference on Frontier in Polymer Science and Technology, Calcutta, INDIA, FEB 10-12, 2006}, month = {NOV}, pages = {891-900}, publisher = {JOHN WILEY \& SONS LTD}, type = {Article}, address = {THE ATRIUM, SOUTHERN GATE, CHICHESTER PO19 8SQ, W SUSSEX, ENGLAND}, abstract = {

The present study is to examine the photo-stabilization effect of an antioxidant on the photo-oxidation of ethylene-propylene-diene monomer (EPDM)-clay nanocomposites. During the preparation of EPDM-clay nanocomposites via melt processing antioxidants are usually incorporated along with clay, which allows phenolic antioxidant molecules to get adsorbed onto acidic clay platelets and their interaction with metallic impurities reduces the stabilizing efficiency of the antioxidant. The nanocomposites were obtained by solution dispersion followed by melt compounding of EPDM and organophilic montmorillonite (OMMT). The samples were characterized by conventional tools such as X-ray diffraction (XRD), Fourier Transform Infra Red (FT-IR) spectroscopy, and thermo-gravimetric analysis (TGA). It was found, upon photo-irradiation (lambda \> 290 nm) studies by following the changes in functional groups and surface morphology, that photo-degradation was lowered by the antioxidant and the efficiency of the antioxidant could be improved by initial incorporation of antioxidant in the EPDM matrix. In EPDM-clay nanocomposites, a stabilizing activity of the antioxidant was observed above some threshold concentration of the antioxidant. The relationship between the nanoclay reinforcement and stabilizing efficiency in terms of photo-oxidation and surface morphology for their applicability are discussed. The methodology adopted for this study is also justified through our observation. Copyright (C) 2007 John Wiley \& Sons, Ltd.

}, keywords = {ethylene-propylene-diene monomer, nanocomposites photo-degradation antioxidant and stabilization}, issn = {1042-7147}, doi = {10.1002/pat.925}, author = {Lonkar, Sunil P. and Kumar, A. Pratheep and Singh, Raj Pal} } @article { ISI:000264434000020, title = {Preparation and nonisothermal crystallization behavior of polypropylene/layered double hydroxide nanocomposites}, journal = {Polymer}, volume = {50}, number = {6}, year = {2009}, month = {MAR}, pages = {1505-1515}, publisher = {ELSEVIER SCI LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

Polypropylene (PP)/layered double hydroxide (LDH) nanocomposites were prepared via melt intercalation using dodecyl sulfate anion modified LDH and maleated PP as compatibilizing agent. Evidently the interlayer anions in LDH galleries react with maleic anhydride groups of PP-g-MA and lead to a finer dispersion of individual LDH layers in the PP matrix. The nanostructure was characterized by XRD and TEM; the examinations confirmed the nanocomposite formation with exfoliated/intercalated layered double hydroxides well distributed in the PP matrix. The nonisothermal crystallization behavior of resulting nanocomposites was extensively studied using differential scanning calorimetry (DSC) technique at various cooling rates. In nonisothermal crystallization kinetics, the Ozawa approach failed to describe the crystallization behavior of nanocomposites, whereas the Avrami analysis and Jeziorny method well define the crystallization behavior of PP/LDH nanocomposite. Combined Avrami and Ozawa analysis (Liu model) also found useful. The results revealed that very small amounts of LDH (1\%) could accelerate the crystallization process relative to the pure PP and increase in the crystallization rates was attributed to the nucleating effect of the nanoparticles. Polarized optical microscopy (POM) observations also support the DSC results. The effective crystallization activation energy was estimated as a function of the relative degree of crystallinity using the isoconversional analysis. Overall, results indicated that the LDH particles in nanometer size might act as nucleating agent and distinctly change the type of nucleation, growth and geometry of PP crystals. (C) 2009 Elsevier Ltd. All rights reserved.

}, keywords = {Layered double hydroxide, Nonisothermal crystallization kinetics, Polypropylene nanocomposites}, issn = {0032-3861}, doi = {10.1016/j.polymer.2009.01.031}, author = {Lonkar, Sunil P. and Morlat-Therias, Sandrine and Caperaa, N. and Leroux, Fabrice and Gardette, Jean Luc and Singh, R. P.} }