Scientific publications

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Title	Year
Multiplication of nuclei during exensional creep. 2003, Manfred Stadlbauer, Hermann Janeschitz-Kriegl, Gerhard Eder, Reinhard Forstner. Multiplication of nuclei during exensional creep. PC 2003 Conference, Linz, Austria Septembe 9-20, 2003 An extensional rheometer for the creep experiment at relatively high tensile stresses has been developed. The new device is called Windbix Extensional Rheometer. "Windbix" is a neologism reminding of the Dutch word for air-gun ("Wind Buks") with reference to the device's pneumatic mechanism to create the tensile force. It is a valueable rheometer, and it can be used also for an investigation of the influence of short term elongation on the structure development of polymers during solidification. It enables the application of defined portions of mechanical work to the polymer sample in its state of undercooled melt. For the purpose intermittent elongational creep is used. With increasing mechanical work the number of nuclei increases by decades. Poster. printme	2003
Polymerization and characterization of longchain branched polyethylene obtained via metallocene catalysis 2003, Jukka Seppälä, Esa Kokko, Anneli Malmberg, Barbro Löfgren. Polymerization and characterization of longchain branched polyethylene obtained via metallocene catalysis Polymer Preprints, 44, 2003, 26 Long-chain branches (LCB) and narrow molecular weight distribution is a novel structure combination in polyethylene, which has only been possible to achieve with single-center catalysis.1-3 LCB, even at very low concentrations, have a strong effect on the polymer melt behavior and, thereby, the processing properties. printme	2003
Morphology formation mechanism by compounding of binary and ternary polymer blends 2003, Tung Pham, H.-J. Radusch, D. Tomova. Morphology formation mechanism by compounding of binary and ternary polymer blends 11. Conference on polymer blends, Merseburg, Germany, 26-27 March, 2003 The physical and application properties of multi-component polymer systems prepared via melt mixing processes are dependent on the properties of the components, the thermodynamic miscibility of the different polymers, the proportions of the components and the quality of the mixture resulting from the mixing intensity of the melt mixing device and the degree of homogeneity, respectively. In polymer blends based on polymer components with semi-crystalline structure, also the crystallization behavior is playing an important part concerning the property level. Furthermore, chemical reactions during mixing, e.g. realized in reactive blending or dynamic vulcanization processes, will influence the morphology and properties of the final polymer system essentially. The mechanism of phase morphology formation are discussed especially for reactive polymer blending. The morphology formation processes running during dynamic vulcanization of binary rubber-thermoplastics blends as well as ternary polyamide-polyamide-rubber blends are discussed in details. The influence of compatibilizers on morphology refinement during dynamic vulcanization and the effect of chemical functionalization of the rubber component in ternary blend systems on the phase structure is shown. printme	2003
Extensional Flow Properties of Linear and Branched Polypropylene and Extension Induced Crystallization. 2003, Manfred Stadlbauer, Reinhard Forstner, Gerhard Eder, Hermann Janeschitz-Kriegl. Extensional Flow Properties of Linear and Branched Polypropylene and Extension Induced Crystallization. AERC - Annual conference of the European Society of Rheology, Guimaraes, Portugal, September 11-13, 2003 Five polypropylene homopolymers with different molecular weight distribution and different degree of long-chain branching have been analysed for their extensional rheology. The elongational flow properties were measured with two methods, i.e. the Rheotens method, and the extensional rheometer Windbix, with which isothermal creep experiments at constant tensile stresses from 5000 to 300000 Pa are performed. In comparison to the behaviour in shear flow, branched PP shows higher viscosity in extensional flow. The difference in shear and extensional rheology is related to long chain branching. Linear polypropylene doesn't show this effect of increased elongational viscosity compared to shear viscosity and follows Trouton's rule. Another interesting aspect of extensional flow of undercooled polymer melts is the multiplication of nuclei. The number of spherulites increases dramatically when the melt of polypropylene is extended isothermally and solidified subsequently at the same temperature well below the melting temperature. It was shown for linear polypropylene homopolymers that the number of nuclei increases by two decades after extensional flow applying 0.2MPa work to the sample. The effects of elongational- and shear flow are compared. It turns out that the specific work applied to the sample is one predictive parameter for the multiplication of nuclei after both, shear and extensional flow. printme	2003
Small Scale Polymerization Systems for Polyolefin Industry 2002, Michael Bartke. Small Scale Polymerization Systems for Polyolefin Industry Speed up Polymer Evolution - Start a Revolution, Seminar Åbo Akademi, Finland, 14-15.2., 2002 No abstract printme	2002
Mastering PE properties by dual site catalyst in staged polymerisation 2002, Arild Follestad, Svein Eggen. Mastering PE properties by dual site catalyst in staged polymerisation Nordic Polymer Days May, 2002 Making low density polyethylene in two-stage low pressure polymerisation processes gives potential for enhanced processing behaviour and end-use polymer properties. This is achieved by optimising molecular weight and comonomer content of two components. A two-stage process which has the higher comonomer level in the last reactor, can even make a copolymer which has one component (the lower molecular weight) with zero comonomer. This is extremely beneficial for many applications. To improve the polyethylene products further, this process can be combined with polymerisation catalysts which have at least two ('dual site') or more different types of active sites. This creates complete control over the molecular weight distribution, extending the potential for further improvements in polymer properties. For instance, vast increase of melt strength can be achieved, as well as reduced tendency to nonwanted polymeric gels. printme	2002
Introduction of long chain branching in linear PE by modification with 1,3-disulfonyl azidobenzene 2002, Jens Kjær Jørgensen, Aage Stori, Keith Redford, Espen Ommundsen. Introduction of long chain branching in linear PE by modification with 1,3-disulfonyl azidobenzene Nordic Polymer Days, Oslo 29.-31.5., , 2002 No abstract printme	2002
Advances in Rotational Moulding 2002, B. Hermstad, F. Haga, Terje Glomsaker, Åge Larsen, Espen Ommundsen. Advances in Rotational Moulding Nordic Polymer Days, Oslo 29.-31.5., 2002 No Abstract printme	2002
Morphology and properties of heterophasic block propylene copolymers 2002, Tung Pham, Norbert Reichelt. Morphology and properties of heterophasic block propylene copolymers 7th European Symposium on Polymer Blends, Lyon, FR, 27-29 May, 2002 Polypropylene (PP) is one of the fastest growing commodity resins in the polymer world market. Compared to other thermoplastics, polypropylene shows very well balanced property picture such as low density, high melting point, high stiffness and low cost. In the world of polypropylene, three main types of materials could be identified, regardless how they are produced: (i) homopolypropylene(homo-PP), (ii) randomcopolypropylene (random-PP) and (iii) heterophasic blockcopolypropylene (heco-PP). In the past, such multiphase PP systems (heco-PP) were generated by mixing / compounding of homo-PP and an external rubber component. Nowadays, using modern technologies, herterophasic PP or impact PP with variable property combinations (flowability, stiffness, impact, thermal expansion, surface etc.) could be produced via multistage reactor arrangements. Furthermore, the property profile of such heco-PP is also strongly influenced by the compounding (homogenisation) conditions such as extruder design, processing parameters etc. In this presentation, the relationship between the polymer parameter, morphology and properties of different heterophasic block propylene copolymers will be discussed. Poster printme	2002
Enhanced Ethylene Plant Planning Model Accuracy by Integrating with Online Optimizer 2002, Bengt-Ove Andersson, Catharina Winberg, Murali Gopalakrishnan, Glenn Cruey, Kheng Lau. Enhanced Ethylene Plant Planning Model Accuracy by Integrating with Online Optimizer 2002 AIChE Spring National Meeting 14th Annual Ethylene Producers Conference Session 100 Process Control New Orleans, Louisiana,March 13,, 2002 Planning LP models are normally built using plant historical data and experience. While the accuracy is adequate the data collection phase is normally time consuming. In the case of the Borealis Stenungsund cracker an existing Real Time Optimisation model was used instead of a normal data collection. This permitted the creation of an extremely detailed LP model with a limited use of plant personnel. printme	2002