| People | Locations | Statistics |
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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Andrade, Maria Madalena Dionísio
Universidade Nova de Lisboa
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (31/31 displayed)
- 2024Cryoprotective Polysaccharides with Ordered Gel Structures Induce Ice Growth Anticipation and Survival Enhancement during Cell Cryopreservationcitations
- 2023Study of the mesomorphic properties and conductivity of n-alkyl-2-picolinium ionic liquid crystalscitations
- 2022Polyhydroxyalkanoates from A Mixed Microbial Culturecitations
- 2022Synthesis and characterisation of ionic liquid crystals based on substituted pyridinium cationscitations
- 2021How Molecular Mobility, Physical State, and Drug Distribution Influence the Naproxen Release Profile from Different Mesoporous Silica Matricescitations
- 2021Influence of natural deep eutectic systems in water thermal behavior and their applications in cryopreservationcitations
- 2021Poly(L-lactic acid)/lithium ferrite compositescitations
- 2019A process engineering approach to improve production of P(3HB) by cupriavidus necator from used cooking oilcitations
- 2017Relaxation behavior of polyurethane networks with different composition and crosslinking densitycitations
- 2017Stabilizing Unstable Amorphous Menthol through Inclusion in Mesoporous Silica Hostscitations
- 2016Dissolution enhancement of active pharmaceutical ingredients by therapeutic deep eutectic systemscitations
- 2016Accessing the Physical State and Molecular Mobility of Naproxen Confined to Nanoporous Silica Matrixescitations
- 2015Design of controlled release systems for THEDES - Therapeutic deep eutectic solvents, using supercritical fluid technologycitations
- 2015Electrical properties of lithium ferrite nanoparticles dispersed in a styrene-isoprene-styrene copolymer matrixcitations
- 2015Dipolar motions and ionic conduction in an ibuprofen derived ionic liquidcitations
- 2014Influence of nanoscale confinement on the molecular mobility of ibuprofencitations
- 2014Conversion of fat-containing waste from the margarine manufacturing process into bacterial polyhydroxyalkanoatescitations
- 2014Ion jelly conductive properties using dicyanamide-based ionic liquidscitations
- 2014Self-standing elastomeric composites based on lithium ferrites and their dielectric behaviorcitations
- 2013New method to analyze dielectric relaxation processescitations
- 2012Probing radiation damage by alternated current conductivity as a method to characterize electron hopping conduction in DNA moleculescitations
- 2012Understanding the Ion Jelly Conductivity Mechanismcitations
- 2011Kinetics of free radical polymerization probed by dielectric relaxation spectroscopy under high conductivity conditionscitations
- 2011Molecular dynamics of poly(ATRIF) homopolymer and poly(AN-co-ATRIF) copolymer investigated by dielectric relaxation spectroscopycitations
- 2011Phase Transformations Undergone by Triton X-100 Probed by Differential Scanning Calorimetry and Dielectric Relaxation Spectroscopycitations
- 2007Dielectric and mechanical relaxation processes in methyl acrylate/tri-ethyleneglycol dimethacrylate copolymer networkscitations
- 2007Temperature modulated DSC study of the kinetics of free radical isothermal network polymerizationcitations
- 2007Origin of glassy dynamics in a liquid crystal studied by broadband dielectric and specific heat spectroscopycitations
- 2006Changes in molecular dynamics upon formation of a polymer dispersed liquid crystalcitations
- 2005Rotational Mobility in a Crystal Studied by Dielectric Relaxation Spectroscopy. An Experiment for the Physical Chemistry laboratorycitations
- 2002Dielectric studies of the nematic mixture E7 on a hdroxypropylcellulose substratecitations
Places of action
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article
New method to analyze dielectric relaxation processes
Abstract
<p>The relaxation properties of polymethacrylates of the n-alkyl series with n=l, 2 and 4 (poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA) and poly(n-butyl methacrylate) (PnBMA)) have been measured and analyzed in order to relate their properties to the size of the lateral side chains. The n-alkyl series has been regarded as a model system and was used in this work to test a graphical data analysis method. Essentially, four relaxation processes were detected in the three polymers: the γ, β, α and αβ relaxations, in increasing order of temperature. It was found that the γ relaxation has a low activation energy, of around 36.3-38.5kJmol<sup>-1</sup>, independent of the side chain, exhibiting low entropy of activation values when referring to the Eyring description of the activation parameters. The β relaxation was found to be similar in PMMA and PEMA, showing an activation energy of 88.8kJmol<sup>-1</sup>, increasing to 112.8kJmol<sup>-1</sup> in PnBMA. The activation entropy was also found to be low for this relaxation, although greater than that for the γ relaxation. In contrast, the α relaxation is quite different in these polymers. We observed a gradual shift in the glass transition temperature towards lower temperatures as the side chain increases in length. The manner in which the α transition makes its way into the dielectric spectra is more abrupt in PMMA than in PnBMA, denoting a higher fragility in the former polymer. Finally, there is a significant difference in the coalescence scenarios of the α and β relaxations for temperatures higher than the glass transition temperature, where they give rise to the so-called αβ relaxation. © 2013 Society of Chemical Industry.</p>