Antonis Gitsas

Borealis Polyolefine GmbH · Innovation and Technology

For various purposes, it is required to compress the shape of the molecular weight distribution (MWD) of polymers into a limited set of parameters. With increasing molecular weight and polydispersity, the MWD data obtained from chromatography become increasingly unreliable due to deficiencies in the high molecular weight region, making estimation v...

Nanocomposite systems comprised of a poly(ethylene vinyl acetate) (EVA) matrix and carbon black (CB) or graphene nanoplatelets (GNPs) were used to investigate conductivity and crys-tallisation dynamics using a commercially relevant melt-state mixing process. Crystallisation kinet-ics and morphology, as investigated by DSC and SEM, turn out to depen...

Knowledge of the solidification behaviour of isotactic polypropylene (iPP) composites with reduced graphene oxide nanoplatelets is key to open the possibility to widespread use of these high performing nanocomposites. The crystallization behaviour of these systems, with filler content in the range of 0.2–3.5 wt% has been investigated by differentia...

The mechanical properties of novel low percolation melt-mixed 3D hierarchical graphene/polypropylene nanocomposites are analyzed in this study. The analysis spans a broad range of techniques and time scales, from impact to tensile, dynamic mechanical behavior, and creep. The applicability of the time–temperature superposition principle and its limi...

Graphene-based materials are a family of carbonaceous structures that can be produced using a variety of processes either from graphite or other precursors. These materials are typically a few layered sheets of graphene in the form of platelets and maintain some of the properties of pristine graphene (such as two-dimensional platelet shape, aspect...

High-voltage direct-current (HVDC) cables are a critical component of tomorrow's power grids that seamlessly integrate renewable sources of energy. The most advanced power cable technology uses crosslinked polyethylene (XLPE) insulation, which is produced by peroxide crosslinking of low-density polyethylene (LDPE). Peroxide crosslinking gives rise...

p>This paper outlines our recent study on effects of cast film extrusion and biaxial orientation on the morphological development and dielectric performance of biaxially oriented polypropylene (PP) films based on two capacitor-grade isotactic PP (iPP) raw materials. Results on polymorphic composition, melting behavior, microstructure and dielectric...

Effects of cast film extrusion and biaxial orientation on morphological development and DC dielectric breakdown performance of non-oriented and biaxially oriented polypropylene (BOPP) films were studied. Cast films, based on two capacitor-grade isotactic polypropylene (iPP) homopolymers, were manufactured using three different extruders under diffe...

The optical waveguiding capabilities of polycyanurate thermoset nanorod (PCNs) arrays mounted on planar gold substrates were investigated using optical waveguide spectroscopy (OWS). The nanorods, with diameter of 60 and 150 nm, and length of 650 nm, are formed by thermal polymerization of cyanate ester oligomers within porous anodic aluminium oxide...

In this review, we summarize some of our efforts in parallel with other research groups' studies in designing, assembling, and structurally and functionally characterizing nanostructured materials using optical waveguide spectroscopy (OWS). We focus on the study of porous nanostructures: (i) cylindrical thin films (ii) mesoporous thin films, and (i...

This contribution summarizes efforts in designing, assembling/synthesizing, and structurally and functionally characterizing nanostructured materials using anodized aluminum oxide (AAO) as a thin-film template. Optical waveguide spectroscopy, using a nanoporous template as the guiding structure, is a particularly powerful analytical tool. The layer...

The present invention is biaxially oriented film comprising a layer comprising a propylene polymer composition comprising a high isotactic homopolymer of propylene and a polymeric α-nucleating agent. The composition may also comprise other propylene polymers.

We demonstrate high-sensitivity biosensing by optical waveguide spectroscopy (OWS) at visible wavelengths using aligned polycyanurate thermoset nanorods (PCNs) arranged in extended arrays as waveguides. The PCNs formed by thermal polymerization of a cyanate ester monomer in self-ordered nanoporous alumina templates were 60 nm in diameter and 650 nm...

The hierarchical self-assembly at the submicrometer, nanometer and α-helical length scales has been studied in a miktoarm star rod−coil chimera composed of poly(γ-benzyl-l-glutamate) (PBLG), polystyrene, and polyisoprene blocks by X-ray scattering, solid state NMR, and transmission electron microscopy. The propensity of the rod block toward α-helic...

The effect of nanoscale confinement on the dynamics of a series of poly(n-octadecyl methacrylate)-b-poly(tert-butyl acrylate)-b-poly(n-octadecyl methacrylate) (pODMA-b-ptBA-b-pODMA) triblock copolymers, synthesized through atom transfer radical polymerization, has been investigated with dielectric spectroscopy as a function of temperature and press...

The effect of pressure on the segmental dynamics in two symmetric blends of PMPS and PS is studied for pressures up to 250 MPa. In these blends, there is interplay between spinodal decomposition and glass transition, resulting in the enrichment of the high Tg component by the more mobile component. The distinctly different pressure sensitivities of...

Nanorods consisting of the polypeptide poly(γ-benzyl-L-glutamate) (PBLG) were synthesized in nanoporous anodic aluminum oxide (AAO) hard templates with pore diameters ranging from 25 to 400 nm. The AAO was immersed in a 1 vol % solution of dried and distilled 3-aminopropyltriethoxysilane (APTES) in anhydrous ethanol for 6 h, rinsed with anhydrous e...

The segmental relaxation process in atactic and isotactic polypropylene (PP) is studied over the temperature (258−323 K) and pressure (0−300 MPa) ranges by means of dielectric spectroscopy. The combined dielectric and equation of state data provide a means of disentangling the relative influence of thermal energy and density on the glass “transitio...

The stability, persistence and dynamics of the peptide secondary motifs are investigated in a series of poly(γ-benzyl-l-glutamate)-b-polyalanine (PBLG-b-PAla) polypeptides through a combination of structural (X-rays, NMR) and dynamic (Dielectric Spectroscopy, NMR) probes. The unfavorable enthalpic interactions between the unlike blocks give rise to...

Στην εργασία αυτή μελετήθηκε η επίδραση της αρχιτεκτονικής καθώς και του περιορισμού και των επιφανειών στην αυτοοργάνωση και στη δυναμική πολυπεπτιδίων, με σκοπό να απαντηθούν ορισμένα ανοικτά ερωτήματα της βιοφυσικής των πρωτεϊνών. Συγκεκριμένα, δεν είναι απολύτως κατανοητός ο τρόπος που η δευτεροταγής δομή επηρεάζεται από την αυτοοργάνωση. Επιπλ...

The effect of chain topology on (i) the peptide secondary structure, (ii) the nanophase self-assembly, and (iii) the local segmental and global peptide relaxations has been studied in a series of model diblock and 3-arm star copolypeptides of poly(epsilon-carbobenzyloxy-L-lysine) (PZLL) and poly(gamma-benzyl-L-glutamate) (PBLG) with PZLL forming th...

We report on the self-assembly and molecular dynamics in a series of poly(γ-methyl-l-glutamate-co-γ-stearyl-l-glutamate) [poly(MLG-co-SLG)] using thermodynamic (differential scanning calorimetry), structural (wide-angle X-ray scattering and 13C solid-state NMR), as well as dynamic (dielectric spectroscopy and site-specific solid-state NMR) techniqu...

The synthesis, characterization and supramolecular organization of rigid–flexible aromatic–aliphatic polyethers are reported. The polymers contain substituted quinquephenyl moieties along their main chains separated by flexible aliphatic units of various lengths. The oligophenylene segments bear different types of dodecyloxy tailed side groups, eit...

The phase state of a series of poly(n-octadecyl methacrylate)-b-poly(tert-butyl acrylate)-b-poly(n-octadecyl methacrylate) (pODMA-b-ptBA-b-pODMA) triblock copolymers, synthesized through atom transfer radical polymerization, has been investigated in bulk and on surfaces using small-angle X-ray scattering and atomic force microscopy, respectively. T...

The structure and the associated dynamics have been investigated in melts of hairy-rod macromolecules composed from a poly(p-phenylene) backbone with sulfonate ester and dodecyl side chains. For the structure investigation, polarizing optical microscopy, differential scanning calorimetry, pressure-volume-temperature, and wide-angle x-ray scattering...