| 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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Jonas, Am
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (13/13 displayed)
- 2015Field-effect memory transistors based on arrays of nanowires of a ferroelectric polymer
- 2014The Ferro- to Paraelectric Curie Transition of a Strongly Confined Ferroelectric Polymercitations
- 2012Optimization of the structural parameters of new potentiometric pH and urea sensors based on polyaniline and a polysaccharide coupling layercitations
- 2011Melting and van der Waals Stabilization of PE Single Crystals Grown from Ultrathin Filmscitations
- 2010pH and Enzymatic Sensors Based on Nanostructured Conductive Polymer Films
- 2010Bidimensional Response Maps of Adaptive Thermo- and pH-Responsive Polymer Brushescitations
- 2006First insights into electrografted polymers by AFM-based force spectroscopycitations
- 2005A theoretical and experimental study of atomic-layer-deposited films onto porous dielectric substrates
- 2005Partial dewetting of polyethylene thin films on rough silicon dioxide surfaces.citations
- 2003Image analysis of transmission electron micrographs of semicrystalline polymers: a comparison with X-ray scattering resultscitations
- 2003Spinodal-like dewetting of thermodynamically-stable thin polymer films.citations
- 2001Characterization of the molecular structure of two highly isotactic polypropylenescitations
- 2000PEEK oligomers as physical model compounds for the polymer. 4. Lamellar microstructure and chain dynamics.citations
Places of action
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article
Characterization of the molecular structure of two highly isotactic polypropylenes
Abstract
Two polypropylenes, PP1 and PP2, produced with different heterogeneous Ziegler-Natta catalytic systems were studied in this work. Preliminary characterization of the non-fractionated materials showed that a low difference in their average tacticity (PP2 > PP1) leads to an important modification of their rigidity properties. In order to establish correlation between the molecular structure parameters and the rigidity properties of these polymers, fractionation of the materials according to crystallizability was performed by means of temperature rising elution fractionation (TREF). Analysis of the fractions of both PP1 and PP2 was carried out by means of C-13 NMR, size exclusion chromatography (SEC), differential scanning calorimetry (DSC) and atomic force microscopy (AFM). The results first showed that TREF does not strictly fractionate PP according to tacticity, but according to the longest crystallizable sequence in a chain. C-13 NMR, SEC and DSC analysis of the fractions demonstrated that the inter-chain tacticity distributions of the polypropylenes is affected by the change of the polymerization conditions, which, in turn, modifies the rigidity properties of the materials. Some results also seem to indicate that the intrachain tacticity distributions are different for the two PP. An AFM study of the elastic modulus was carried out for the first time on the TREE fractions. It showed that the rigidity or the fractions strongly increases as the TREF elution temperature increases in accordance with a concomitant increase of isotacticity and the crytallinity of the fractions. PP2 TREE fractions were, moreover, found to exhibit a higher elastic modulus than PP1 TREF fractions at all elution temperatures. This study allowed us to further identify the TREF fractions that were responsible for differences in rigidity. To summarize, it is shown how the experimentally observed increase of the average rigidity of one of these two polypropylenes can be rationalized via information collected from a TREF fractionation. ...