Scientific publications

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Title	Year
Molecular stress function theory and analysis of branching structure in industrial polyolefins 2009, Saeid Kheirandish, Manfred Stadlbauer. Molecular stress function theory and analysis of branching structure in industrial polyolefins J.Therm.Anal.Calorim., - (98), 2009, - Despite substantial progress in analytical techniques for polymer characterization, a realistic picture of branching structure in industrial polymers still remains at large. Using a number of assumptions, structure-based constitutive models can distinguish between linear and branched structures in a qualitative sense. More detail on branching architecture, such as the number and length of side chains, the sequence in which they exist on the backbone and their contribution to polymer chain relaxation is more or less unknown. In the current study, elongational behavior of four commercial polyolefins is compared using the predictions of the MSF (molecular stress function) theory. The results will then be used to analyze the branching in a group of strain-hardening polypropylenes synthesized using single site catalyst. printme	2009
The use of DMTA for predicting standard mechanical properties of developmental polyolefins 2009, Markus Gahleitner, Christelle Grein, Klaus Bernreitner, Bernhard Knogler, Elisabeth Hebesberger. The use of DMTA for predicting standard mechanical properties of developmental polyolefins J.Therm.Anal.Calorim., - (98), 2009, 623–628 The correlation of linear data from dynamic-mechanical testing (DMTA) to nonlinear data from standard mechanical testing was attempted for a number of quite different polypropylene-based compositions. For limited composition ranges, correlations between storage modulus and stiffness as well as between loss angle integrals and impact strength could be achieved. Challenges in trying to correlate DMTA tests to standard mechanics clearly result from morphology effects at different scales, both in crystallinity and flow-induced superstructures (orientation) and in multiphase impact copolymers or composites. While a relative scaling turned out to be easy, absolute prediction is difficult. printme	2009
LDH as Nanofiller: Organic Modification and Dispersion in Polymers 2009, Francis Costa, Andreas Leuteritz, Juliane Meinl, Udo Wagenknecht, Gert Heinrich. LDH as Nanofiller: Organic Modification and Dispersion in Polymers Eurofillers 2009 Conference, Alessandria / IT, - (-), 2009, - Layered double hydroxide (LDH) is a relatively new class of layered crystalline clay materials to be used as nanofiller in various polymer matrices. We report here about the organic modification of LDH based on anionic surfactants having different sizes and functionalities. Subsequently, their dispersion in polymer is discussed and finally the characteristics of the polymer/LDH nanocomposites are investigated. LDH has been modified using regeneration method, which shows that irrespective of size and functionality of the anionic surfactant, organic modification can be carried out efficiently. However, it has been observed that alkyl sufonate are more efficiently intercalated within LDH layers than other surfactants giving well defined crystal structure of the modified LDH. These modified LDH, when dispersed in polymers shows that not only the size of the surfactant, but also the functionality of the surfactant influence their dispersion in a non polar polymer matrix. printme	2009
Different Approaches Towards PP with Strain Hardening Behaviour 2009, Tung Pham. Different Approaches Towards PP with Strain Hardening Behaviour Polymermischungen 2009 Conference, Merseburg / DE, - (-), 2009, - In the present study different approaches towards PP with strain hardening behavior have been evaluated. On the one hand we had the current commercial process comprising reactive processing of linear PP homopolymer in the presence of peroxide and co-agent. On the other hand we have exploited an alternative process using PP copolymers with minor amounts of tertiary dienes e.g. 7 methyl-1,6 octadiene). It was shown that such materials provide a starting product for initiating long chain branches and pronounced strain hardening behavior by subjecting to free radicals, i.e. beta irradiation and peroxide treatment. The most pronounced strain hardening was achieved at a irradiation dose of 30 kGy. The advantages of the approach using PP-tertiary diene precursors could be summarized as follows: * very low amount of diene is sufficient (e.g. 0.3 mol%) * o other chemical substances (e.g. chain extenders) are involved, which would result in i) more stable production ii) less contamination (no volatiles) in end product * better possibilities to design the molecular structure are given Further on, it can be stated that by subjecting propylene-co-7 methyl-1,6 octadiene polymers to free radicals an improved strain hardening behavior with no negative effect on the mechanical properties could be achieved. printme	2009
Turning Market Needs into Innovative Polyolefin Products 2009, Alfred Stern. Turning Market Needs into Innovative Polyolefin Products APST01 - Advances in Polymer Science and Technology, Linz, Austria, 2009 The dynamic development of today's polymer markets presents polymer producers with the continuous challenge to combine the quick reaction to customer demands with parallel basic developments to enable breakthrough achievements. For polyolefins, this can be achieved by combining different levels of structural design: polymerization catalysts, production processes, structural models and processing knowledge can supplement each other to achieve radical product progress and enable new application areas. The recent achievements of customer-centered polyolefin development at Borealis will be illustrated by three case studies: - Sterilizable films & stand-up pouches: For applications ranging from food to medical packaging it is required to establish understanding of the effects before designing the materials. Both semi-stiff and very soft solutions could be developed by intelligent phase structure design. - Transparent & tough bottles: From extrusion blow molding to injection stretch blow molding, polypropylene can cover a wide range of clarity/toughness combinations. Polymer design and nucleation must be aligned in a clever way for this purpose. - Automotive exterior components: While PP-based bumpers are a standard element; recent developments enable body panels and load-bearing components for passenger cars and trucks. The importance of compound development and intense customer co-operation will be outlined. There's always a market for good ideas - whether reacting to market requirements or even anticipating them. Borealis will continue to work at the forefront of polymer development together with customers and suppliers and invites partners from academia to join in these efforts. printme	2009
Portfolio strategy for generating IP value 2009, Erik van Praet, Markus Gahleitner. Portfolio strategy for generating IP value The Handbook of European Intellectual Property Management, 2009 As a leading provider of innovative polymer solutions, Borealis has significantly improved its Intellectual Property Rights (IPR) position in recent years. An important element for this was an integrated portfolio strategy aligned across both the central Innovation and Technology (InnoTech) department and the business units of the company. This system provides guidance for decisions regarding development, protection, licensing and oppositions, making sure that both InnoTech and IPR investments are well placed. printme	2009
Single-Site Catalyst Development within Borealis â From Metallocene to Catalyst and Beyond 2009, Peter Denifl. Single-Site Catalyst Development within Borealis â From Metallocene to Catalyst and Beyond APST01 - Advances in Polymer Science and Technology, Linz, Austria, 2009 During the last years metallocenes have been proven to be increasingly of interest for the production of polyolefins also in commercial scale. Even if their commercialization has been slower than first anticipated, they are now well established and regarded as a crucial technology for the future development of the polyolefin industry. Compared to conventional Ziegler-Natta catalysts they offer remarkable advantages, especially the possibility of tailoring polymer structure and consequently product properties to a degree that is far beyond that which can be achieved with heterogeneous, state-of-the-art multi-site catalysts. The possibility to adjust and control the polymer's micro structure with single-site systems is inherently linked to the ability to tailor the steric and electronic environment around the well defined polymerization active transitional metal centres. In addition, developments within the field of co-catalysts and complex activation play a big role. At present, the low pressure production of semi-crystalline polyolefins is almost exclusively based on gas- or slurry-phase polymerization process technology. In order to be able to exploit the full potential of single-site catalysts in such a process, i.e. high productivity, narrow molecular weight distribution, uniform comonomer incorporation, and stereoselectivity in the case of polypropylene, they need to fulfill the same particle-forming requirements as traditional heterogeneous catalysts. Even if during the last decades a significant number of heterogenization concepts for different types of olefin polymerization catalysts have been developed, the realization of a single-site catalyst tailored for a particular process still remains a difficult challenge. The intention of this presentation is to provide an overview of the recent developments in the field of heterogeneous single-site catalysts. In combination with advanced polymerization process technology these catalysts give access to improved polymer properties, and allow increasingly to exploit also in commercial scale the significant potential which single-site systems have to offer. As an example, and to highlight some of the most important aspects that need to be taken into consideration when developing such heterogeneous polymerization catalysts, Borealis' proprietary Sirius technology will be discussed. In contrast to most heterogenisation methods for transition metal compounds which are based on direct absorption of catalyst components on porous supports, the application of the emulsion-based Sirius technology results in highly active catalyst particles with excellent particle morphology without use of an external carrier. In addition, the self-supported catalyst particles obtained via emulsion technology exhibit a uniform distribution of active sites across the entire particle, resulting in an excellent inter- and intra-particle homogeneity. printme	2009
Controlling the Thermal Expansion in Polypropylene Compounds 2009, Claudia Kniesel, Cornelia Kock. Controlling the Thermal Expansion in Polypropylene Compounds APST01 - Advances in Polymer Science and Technology, Linz, Austria, 2009 Polymers are often used together with metals, especially for automotive applications. Since the thermal expansion of polymers is approximately four times higher than for metals, dimensional mismatches between polymer based materials and metal parts can occur with temperature changes. The polypropylene based exterior parts for the automotive industry are made out of heterophasic systems (rTPO) produced in a reactor cascade consisting of a polypropylene matrix and rubber inclusions. The challenge in product design is the right combination of high flow / low CLTE and acceptable mechanical properties. The aim of this research was to investigate the possibility of controlling the thermal expansion by tailoring the morphology of the resulting compounds. According to literature1, co-continuous rubber matrix morphology will inhibit thermal expansion in the flow direction. Hence the influence of different concentrations of C2/C8 plastomers in the rTPO on the thermal expansion was investigated. Plastomers and rTPOs with different flow behaviours were chosen as components for the analyses in order to study the influence of the flowability of the composing materials. It is shown that a reduction in thermal expansion occurs if the shape of the rubber particles is changed from spherical to elongated or co-continuous. If this morphology is obtained in compounds also containing a certain amount of talcum, the enhancement in terms of thermal expansion becomes remarkable due to a combination of mechanical restrain induced by the filler and morphological effects through the co-continuous structure. printme	2009
Borstar PP 2G: Towards Reducing Emissions 2009, Vijay Sameer, Juha Hartikainen. Borstar PP 2G: Towards Reducing Emissions APST01 - Advances in Polymer Science and Technology - Linz, Austria, - (-), 2009, - With higher penetration of PO’s in demanding markets, the product requirements have become increasingly stringent. In interior use in cars, emission and fogging compounds are undesirable. In water applications, such as pipes, caps & closures specifications indicating migration of taste & odour components and unintended added substances have become stricter. Presence of emission causing compounds (e.g. VOCs) in the polymer product from plants cause challenges along Borealis’ chosen path of creating value for its converters, end-users and consumers. In some instances, these compounds migrate out in time, accumulate or concentrate and create safety hazards as in silos & storage. Emissions resulting from hydrocarbons in polymer and T&O components are two different problems and are resolved differently. While T&O components could be from the raw material impurities or production noise, most of the hydrocarbons which are the cause of emissions originate within the PO process itself. These hydrocarbons include residual monomer and co-monomers, process agents, oligomers and waxes. Numerous solutions for reducing these hydrocarbons from the polymer are in place commercially and some of them have been incorporated in Borstar PP 2nd generation process technology. printme	2009
Melt Flow Instabilities of Wood Polymer Composites 2009, Velichko Hristov. Melt Flow Instabilities of Wood Polymer Composites Compos.Interf., 16 (-), 2009, 731-750 Melt flow instabilities during extrusion of wood polymer composites (WPC) containing 30–60 wt% wood flour (WF) have been investigated. The research emphasized elucidation of the extrudate surface tearing mechanism and its relation to wall slip. This interesting phenomenon has been known in the WPC industry for years; however, it has not received much research interest. It was observed that increasing the wood flour loading up to 50 wt% aggravated the surface tearing; however, addition of 60 wt% wood flour completely eliminated the surface defect due to strong wall slip and plug flow. It was also found that addition of lubricants and increasing the shear rate significantly improved the surface appearance of the filled compounds. Molecular weight and molecular weight distribution of the polymer matrix influence the melt flow properties of the composites. The significance of the entrance pressure measurement and its usefulness for quantitative assessment of filler–matrix interactions in composite materials is also demonstrated in this paper. printme	2009