Scientific publications

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Title	Year
Thin Film Structure of Block Copolymer−Surfactant Complexes: Strongly Ionic Bonding Polymer Systems 2012, Jingbo Wang, Wim H. de Jeu, Paul Müller, Martin Möller, Ahmed Mourran. Thin Film Structure of Block Copolymer−Surfactant Complexes: Strongly Ionic Bonding Polymer Systems Macromolecules, 45 (-), 2012, 974−985 We present a structural investigation of thin films of diblock copolymers PS−P4VP in which 4VP forms an ionic bond with a sterically demanding surfactant, bis (2-ethylhexyl) sulfosuccinate acid (AOT). The results depend strongly on the interplay between microphase separation and surfactant ordering. Protonation of the P4VP homopolymer or diblock PS-b-P4VP with AOT leads to a multilayer structure in which the surfactant determines the layer thickness. In thin films of the protonated block copolymer, the segregation between the blocks generates nanostructures with an inplane periodicity defined by the molecular masse of the copolymer and the stoichiometry of the complex. Variation of the composition of the blocks and the molar ratio AOT/pyridine leads to structural transitions: cylinders of (AOT/P4VP) → lamellae → cylinders of PS. Remarkably, regardless of the morphology, the bcp microdomain structure remains orthogonal to the air substrate interface. Finally, we show that hydrolysis of AOT results in the formation of pores with a variable geometry useful for templating two-dimensional inorganic structures. printme	2012
Synergistic mechanical effects of calcite micro- and nanoparticles and beta-nucleation in polypropylene copolymers 2012, Markus Gahleitner, Christelle Grein, Klaus Bernreitner. Synergistic mechanical effects of calcite micro- and nanoparticles and beta-nucleation in polypropylene copolymers Eur.Polym.J., 48 (-), 2012, 49–59 For improving the understanding of mechanical effects in micro- and nanocomposites based on polypropylene (PP) copolymers and precipitated or ground calcium carbonate (PCC or GCC), especially in the presence of significant portions of the beta-modification, a set of compounds based on different PP grades and fillers with optional beta-nucleation prepared by melt compounding was studied. A synergistic improvement of mechanical properties by a combination of calcite particles and -nucleation was found for two of the investigated high-impact base polymers up to 20 wt% of nanofiller. While in the past research positive toughness effects were always limited to PP homopolymers with a moderate original impact strength and to particles of less than 100 nm average diameter, the toughness of high impact ethylene-propylene impact copolymers could be increased by more than 150% even at sub-zero temperatures where the failure behaviour is determined by the disperse elastomer phase. printme	2012
Nucleation of Polypropylene Homo- and Copolymers: A Review 2011, Markus Gahleitner, Christelle Grein, Saeid Kheirandish, Johannes Wolfschwenger. Nucleation of Polypropylene Homo- and Copolymers: A Review Intern.Polym.Proc., 16 (1), 2011, 2-20 The combination of moderately slow crystal growth at large undercoolings together with the practical absence of sporadic nucleation makes isotactic polypropylene (iPP) an ideal material for controlled nucleation. In this review the different types of nucleating agents – inorganic and organic, particulate and soluble – for the different crystal modifications of iPP (alpha, beta and gamma) are presented together with their working mechanism and criteria for activity. The interaction between polymer type, nucleating agent and processing conditions in determining mechanical and optical properties conclude the survey. printme	2011
Value Added Innovation in PP: Satisfying long term need? 2011, Michel Daumerie, Markus Gahleitner. Value Added Innovation in PP: Satisfying long term need? SPE Polyolefins Conference 2011, - (-), 2011, - When plastics are discussed in public, the focus is often rather on problems caused than on solutions provided by this class of materials. In the relationship between energy or raw material demand on the one hand and the performance and user-friendliness on the other hand, Polypropylene is certainly one of the best and most versatile plastic material bringing many technical advantages as packaging material or material in very technical application in addition to a rather favourable energy and raw material demand for a sustainable supply of the world population with both engineering and packaging materials. Advanced packaging systems based on polypropylene range from very soft film pouches – like for medical uses – to containers combining high stiffness and heat resistance – like thin-wall pails for convenience and dairy products. Common to all of these systems are the demands for high purity and low weight or wall thickness, frequently in combination with transparency and toughness. Proper combination of Borealis’ proprietary catalyst systems with the Borstar® polymerization technology and the BNT nucleation system is enabling the development of a new generation of innovative polypropylene grades with clear advantages for both converters and consumers. The advantages are best expressed by five product groups answering to essential market needs: - BorPure™ with best organoleptic properties and low extractables - Borclear™ with high transparency and sterilization resistance - Borseal™ with low seal initiation temperature (SIT) and broad sealing range - Borpact™ ethylene-propylene interpolymers combining toughness and transparency in an unprecedented way - Borsoft™ random-heterophasic copolymers for extreme softness In all cases, market input and a deep understanding of structure/property correlations has been essential. Borealis is supporting this development with expansion in both production and innovation, from the recently inaugurated International Innovation Centre in Linz, Austria, to new production units in Germany, Sweden, Austria, and the Borouge Joint Venture in Abu Dhabi (UAE). printme	2011
Making Sure that Looks Are not Deceiving 2011, Georg Grestenberger, Sybille Simon, Klaus Lederer, Umut Cakmak. Making Sure that Looks Are not Deceiving Kunststoffe International, - (3), 2011, 58-61 Contrary to classical surface properties such as scratch resistance or glossiness, it is far more difficult to quantify haptic characteristics. Nonetheless, surface properties with names like Soft Touch, Cool Touch or Silky Touch have gained increasing importance in the plastics industry during recent years. For this reason, a new testing method has been developed that is intended to make research and developments in surface quality more efficient. printme	2011
Functioning Mechanisms of Nucleating Agents for PP: Insights from Rheology 2011, Saeid Kheirandish, David Friel. Functioning Mechanisms of Nucleating Agents for PP: Insights from Rheology DRG Annual Meeting Berlin 2011, - (-), 2011, - Generally, NAs (Nucleating Agents) are added to injection-molding grades of polypropylene to reduce processing time through an increase in Tc, enhance stiffness and reduce optical haze. The most efficient NAs to modify the latter property, namely transparency, are usually referred to in the literature as “Soluble Nucleating Agents” as opposed to alternative inorganic, particulate nucleating agents and organic salts. The main two generic chemical structures in the soluble family of NAs are sorbitols and trisamides. Unlike organic-salt-based NAs, sorbitol-based NAs are known to have a comparably lower melting temperature, melting at the application temperature of the base resins and forming a fibrillar network in the melt that is highly soluble in PP. This creates a fine, homogeneous dispersion with minimized scattering of light, or as with trisamides, can create self-assembled strucruesstructures of highly ordered supra-molecular stackings that are typical of discotic liquid crystals. The flow-related aspects of PP nucleation by soluble NAs have been studied by several groups. The gel-point of a polypropylene nucleated with a soluble NA is the exact tempeprature at which a sudden increase in the elastic modulus (or viscosity) of the melt is observed. The characteristic lower crystallization speeds of sorbitol-based NAs, as seen in time sweep measurements, is attributed to the lower mobility of sorbitol clusters which can rearrange slowly within the melt. Adding to the amount of NA in PP causes T2 to shift to higher temperatures, followed by a “saturation” concentration beyond which no improvement in nucleation efficiency is seen and NA starts to become insoluble in PP. We aim here to address the applications of precise rheological techniques in finding structurally meaningful interpretations of the correlation between PP structure and the efficiency of nucleating agents. printme	2011
Microstructural Characterisation of Multimodal Polyolefins using different Fractionation techniques 2011, Andreas Albrecht, Christian Piel. Microstructural Characterisation of Multimodal Polyolefins using different Fractionation techniques APST02 Conference Linz, 27.-29.09.2011, - (-), 2011, - The determination of the chemical heterogeneity of synthetic polymers is crucial for understanding structure-property relationships, polymerization mechanisms and kinetics, and polymer reaction engineering. Different separation techniques fractionate the polymer regarding specific characteristics of their microstructures e.g. molecular weight, chemical composition, comonomer sequence length, tacticity, and long-chain branching. For being able to explain the performance of a product or to develop new products it is important to obtain a full profile of the chemical heterogeneity (molecular weight distribution along the chemical composition distribution or vice versa). Therefore cross fractionation techniques can be applied. These techniques are temperature rising elution fractionation (TREF) coupled with size exclusion chromatography (SEC), two-dimensional high performance liquid chromatography (2D-HPLC), or a preparative fractionation followed by SEC and nuclear magnetic resonance (NMR) spectroscopy. Beside cross fractionation techniques hyphenated techniques like size exclusion chromatography coupled to Fourier transform infrared spectroscopy (SEC-FTIR) SEC-IR (composition detector), or TREF coupled with online viscosimeter(TREF-VISC) can be a good practical solution for the elaboration of a deeper understanding of material properties in polyolefin research and product development. In this work we will present the resolution of cross fractionation techniques and their limitations or benefits versus hyphenated techniques, as SEC-FTIR or SEC-IR. Two applications of both techniques inside the polymer industry are presented and discussed in detail. printme	2011
HDPE-g-MAH modified with hydroxylated melamine derivatives 2011, Yi Liu, Christoph Hahn, Rene Dicke, Tung Pham. HDPE-g-MAH modified with hydroxylated melamine derivatives APST02 Conference Linz, 27.-29.09.2011, - (-), 2011, - Recent investigations showed the possibility of modifying maleic anhydride grafted high density polyethylene (HDPE-g-MAH) with hydroxylated melamine derivatives. HDPE-g-MAH was compounded with four melamine derivatives (loading rate of 5wt%) that have different number of hydroxyl groups respectively. Samples were first characterized with FTIR and rheology for evidence of successful reactive modification. FTIR analysis suggests that all melamine derivatives reacted with HDPE-g-MAH; moreover, compared to HDPE-g-MAH, all compounds possess a significant increase in complex viscosity, suggesting the formation of a network. More compounds were prepared for mechanical testing and it is found that they gained improvement in either flexural modulus or impact strength. Although no marked difference is seen between the modified polymers and the virgin HDPE-g-MAH in their DSC curves, some compounds show increased heat deflection temperature (HDT). printme	2011
Advanced polypropylene glass fibre compound - A cost efficient way to replace PA 2011, Thomas Wagner. Advanced polypropylene glass fibre compound - A cost efficient way to replace PA SPE TPO Conference, Detroit, MI, United States, Oct. 3-6, 2011, - (-), 2011, - The Borealis Borstar process provides the key success factor to create Advanced Compounds for the Automotive industry. Borealis produced air intake manifold from advanced PP-GF Xmod GB306SAF. The Xmod GB306SAF is a patented recipe of polypropylene with 35% short glass fiber which offers long-term high heat and chem. resistance, combined with high fatigue and a broad operating temp. between -40°C and +120°C independent from conditions such as humidity. In addition, Borealis also developed the Xmod GB302HP, PP-GF used for rear seat carriers at BMW. The Xmod GB302HP is a 30% short glass fiber reinforced polypropylene compd. based on high crystallinity PP resin. It is customized to the application demands and to support the BMW SGI foaming process. printme	2011
Designing polymeric nanorod arrays for optical waveguide-based biosensors 2011, Antonis Gitsas, Thomas D. Lazzara, Basit Yameen, Martin Steinhart, Wolfgang Knoll, Hatice Duran. Designing polymeric nanorod arrays for optical waveguide-based biosensors Phys. Status Solidi , C 8 (11-12), 2011, 3179–3182 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 templates. We discuss the waveguiding properties of the PCNs arrays when the nanorod diameter is much smaller (<1/10) than the wavelength of the guided light. We monitored the changes in the waveguiding modes by exchanging the interrod filling environment with water, ethanol, and isopropanol. This study led to a sensing figure of merit as high as 196 reciprocal refractive index units, which is higher than that of other previously studied sensors based on angular modulation. Furthermore, numerical simulations were performed by applying an Effective Medium Theory (EMT) based on the Maxwell-Garnett approximation for the prediction of the optical properties of anisotropic nanorod arrays. Simulations based on Fresnel equations were used for estimating the optimal fabrication geometry, with varying the nanorod diameter and the interrod distance. Based on these results, we introduce the applicability of the PCNs arrays platform as a concept in optical biosensors and other related applications. printme	2011