Scientific publications

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Title	Year
Orientation and phase content of high density polyethylene blown film 2006, Einar L. Hinrichsen, Åge Larsen, B.S. Tanem, Irene Helland, Arild Follestad. Orientation and phase content of high density polyethylene blown film COST P12 Conference; Crystallisation and Structure Formation of Polymers, Mittelwihr Center France, 9-11 October 2006, 2006 Poster; - We present results from a study on HDPE films including materials of different molecular structure and produced with varying film draw-down. The study was motivated by the fact that density alone does not explain variations in film permeability. Further, increasing film line stress also has been reported to yield morphologies more open to permeants. In HDPE blown film high stress is known to lead to a row-nuclei morphology overgrown by radially orientated, no-twist lamellae with dominant c-axis MD orientation. These structures have been referred to as Keller-Machin 2 morphology and the orientation of the lamellae in this case could result in lower tortuosity of the diffusion path. The published results may have been based on films produced using increased draw-down to decrease the film thickness, thus possibly altering crystalline orientation. A row-nuclei structure is detected by AFM. More details on the orientation are obtained from IR spectroscopy - IR dichroic ratios as well as IR trichroism. Raman spectroscopy was applied to analyse the phase composition, giving the fractions of crystalline, amorphous and crystal-like interphase. Further details on orientation and lamellar structure were derived from SAXS. The results show the influence of material structure and film line stress on formation of row-nuclei and lamellar orientation. printme	2006
Computer Aided Polymer Design Using Group Contribution Techniques 2006, Martin Hostrup, Peter.M. Harper, Øivind Moen, Nuria Muro-Sune, Vipasha Soni, Jens Abildskov, Rafiqul Gani. Computer Aided Polymer Design Using Group Contribution Techniques Multiscale Modelling of Polymer Properties 257, M. Laso, E.A. Perpete (Editors), Chapter 4, 2006, 257-299 This chapter highlights certain aspects of polymer design and analysis through the use of systematic computer aided techniques. Different polymer design and analysis, starting with the simple problem of design of polymer repeat units based on a set of pure polymer (repeat unit) properties and ending with complex problems involving design of polymer blends plus additives to satisfy a set of functional properties of the polymer-based chemical product, are highlighted. Solution of all these problems require the evaluation of different sets of end-use properties related to the polymer (depending on the micro-structure as well as macroscopic structure of the polymer). In the design of polymer repeat units, only end-user properties based on the macroscopic structure is sufficient, while in more complex problems involving polymer blends, transport properties or configuration of repeat units, microscopic structural properties also play an important role. Also, as the search space for the polymer design problem is potentially very large, computer aided techniques that can reliably reduce the search space and identify a feasible set of alternatives within which the optimal solution may lie, is an option worth investigating. printme	2006
From polyethylene rheology curves to molecular weight distributions 2006, Costas Kiparissides, Prokopis Pladis, Øivind Moen. From polyethylene rheology curves to molecular weight distributions Multiscale Modelling of Polymer Properties 241, M. Laso, E.A. Perpete (Editors), Chapter 3, 2006, 241-255 It has been shown that Molecular Weight Distributions can be determined from linear viscoelastic melt properties (shear storage modulus G' (CD) and the stress relaxation modulus G (t). A method for the determination of Molecular Weight Distributions from viscosity-shear rate data would have the following two advantages: 1. A piston rheometer can be utilized to perform the necessary measurements. These rheometers are more convenient in use and are more robust instruments than the mechanical spectrometers that are used to measure G' (co) and G(t). 2. In order to use the G' (o) and G (t) methods it is essential that the Plateau modulus (G^ ) must be known. This is a very difficult, and sometimes impossible, quantity to measure. A knowledge of the Plateau modulus (G^) is not required for the viscosity method that is going to be described next. printme	2006
Multiphase PP Blends with Improved Surface Characteristics 2006, Doris Machl, Christelle Grein, Klaus Bernreitner. Multiphase PP Blends with Improved Surface Characteristics 8th Austrian Polymer Meeting 2006, Linz/Austria, September 20-22, 2006 The design of multiphase PP material with improved surface characteristics is still an ongoing challenge in the industry. This recent study will outline fundamental research on surface properties like scratch and gloss performance in PP/EPR blends consisting of a PP matrix and a dispersed EPR phase with crystalline PE core particles. Each phase and the interactions between them is expected to influence the properties (also near the surface) of the material. Different spectroscopic measurements like Transmission Electron Microscopy (TEM), Atomic force microscopy (AFM) and confocal laser microscopy (CLM) were used to understand the characteristics of these multiple structural factors. A link to the requirements in the automotive industry as one of the important application areas in this field will be highlighted. printme	2006
Optimization of run parameters of temperature-rising elution fractionation with the aid of a factorial design experiment 2006, Nicolai Aust, Markus Gahleitner, Bettina Raninger. Optimization of run parameters of temperature-rising elution fractionation with the aid of a factorial design experiment Polymer Testing, 25, 2006, 896-903 The effects of start temperature for crystallization, cooling rate, heating rate, and elution speed on the separation quality of temperature-rising elution fractionation (TREF) were studied using a heterophasic ethylene/propylene copolymer. The results derived by the aid of a factorial design plan were judged by the separation quality and visibility of the various peaks and shoulders in the overall diagram. Optimized run parameters were found which finally led to a remarkable increase in resolution of the TREF curve of the copolymer. printme	2006
Morphology and Mechanical Properties of Polypropylene/Polyamide 6 Nanocomposites Prepared by a Two-Step Melt-Compounding Process 2006, Markus Gahleitner, Bernd Kretzschmar, Doris Pospiech, Elisabeth Ingolic, Norbert Reichelt, Klaus Bernreitner. Morphology and Mechanical Properties of Polypropylene/Polyamide 6 Nanocomposites Prepared by a Two-Step Melt-Compounding Process Journal of Applied Polymer Science, 100, 2006, 283-291 Polypropylene/polyamide 6 blends and their nanocomposites with layered silicates or talc were prepared in a melt-compounding process to explore their mechanical performance. The thermomechanical behavior, crystallization effects, rheology, and morphology of these materials were studied with a wide range of experimental techniques. In all cases, the inorganic filler was enriched in the polyamide phase and resulted in a phase coarsening of the polypropylene/polyamide nanocomposite in comparison with the nonfilled polypropylene/polyamide blend. The mechanical properties of these nanoblends were consequently only slightly better than those of the pure polymers with respect to the modulus, whereas the impact level was below that of the pure polymers, reflecting the heterogeneity of the nanoblend. Polymer-specific organic modification of the nanoclays did not result in a better phase distribution, which would be required for better overall performance. printme	2006
Melt viscosity and phase structure predictions for Ethylene-Propylene Copolymers 2006, Christelle Grein, Markus Gahleitner, Bernhard Knogler, Susanne Nestelberger. Melt viscosity and phase structure predictions for Ethylene-Propylene Copolymers Annual European Rheology Conference (AERC) Hersonissos, Greece,26.-28.April, 2006 One of the key factors to a better understanding of the phase morphology of high-impact EP copolymers is the knowledge of the rheological behaviour of the various phases in these complex systems. Next to the molecular weight distribution also the comonomer content affects the viscosity, as could be demonstrated in a systematic study of a wide range of compositions. More specifically, this means that at a given molecular weight the zero shear viscosity of the EPR- and PE-phases of such an impact copolymer are up to orders of magnitude higher than the respective PP phase. This will have a significant effect on the phase morphology of these compositions. Moreover, for the PP matrix the viscosity curve as a function of shear rate could be modeled rather easily using a Carreau-Yasuda approach; this was much more difficult for the copolymer components. As a consequence, the viscosity ratio between the different phases changes significantly with shear rate, meaning again that the phase morphology dependence on shear history (compounding and processing operations) can be understood better that way. printme	2006
Optical Properties of Highly Transparent Polypropylene Cast Films: Influence of Material Structure, Additives, and Processing Conditions 2006, Gernot Wallner, Christian Teichert, Katharina Resch, Günther Maier, Markus Gahleitner. Optical Properties of Highly Transparent Polypropylene Cast Films: Influence of Material Structure, Additives, and Processing Conditions Polymer Engineering and Science, 46, 2006, 520-531 Polypropylene homopolymers and ethylene/propylene-random-copolymers formulated with and without anti-blocking additives were extruded to cast films with an industrial scale extruder equipped with a soft box, a specific air knife that expels a higher volume of air at lower velocity. The films were analyzed as to their optical properties haze and clarity. A comprehensive topographical characterization was performed using atomic force microscopy (AFM) and confocal microscopy. To obtain morphological information on a nanometer scale AFM phase imaging, micro-thermal analysis and small angle X-ray scattering (SAXS) were done. A significant effect of additives and processing conditions on the film topography and the optical properties was revealed. The films without anti-blocking and antacid aids showed the best optical properties and lowest vertical roughness fluctuations. In contrast, the addition of anti-blocking and antacid aids reduced the optical properties associated with an increase in surface roughness. While for films without anti-blocking aids an enhanced soft box condition resulted in lower vertical fluctuations of roughness and better optical properties, the behavior was in reverse for films with anti-blocking aid. By means of SAXS crystalline lamellae with a thickness of about 2.5 nm were detected. High-resolution phase imaging AFM yielded thicker crystal lamellae on the film surface. printme	2006
Distribution of Calcium Carbonate and Silicone Elastomer in a Flame Retardant System Based on EthyleneAcrylate Copolymer, Chalk and Silicone Elastomer and Its Effect on Flame Retardant Properties 2006, Anna Hermansson, Thomas Hjertberg, Bernt-Åke Sultan. Distribution of Calcium Carbonate and Silicone Elastomer in a Flame Retardant System Based on EthyleneAcrylate Copolymer, Chalk and Silicone Elastomer and Its Effect on Flame Retardant Properties Journal of Applied Polymer Science, 100, 2006, 2085-2095 A combination of microscopy studies (SEM, ESEM/EDX, and TEM/EDX) is proven to be useful in locating chalk particles and silicone elastomer in a flame retardant system based on ethyleneacrylate copolymer, chalk, and silicone elastomer. The dispersion of the two additives was also obtained. The chalk particles were visually observed (at a certain degree of magnification), and the silicone elastomer was detected using characteristic X-ray mapping and line scans. The analysis provided a good contrast between chalk particles and silicone elastomer in the surrounding polymer matrix. It is shown that dispersion of the additives depends on the mixing conditions, where tougher mixing conditions improve dispersion. A discussion is given on how dispersion correlates with the flame retardant properties of this system printme	2006
Biodegradable Plastrics in Packaging Applications 2005, Geir Kristian Johnsen. Biodegradable Plastrics in Packaging Applications PIRA Conference, Leatherhead, UK, 5-6 July, 2005 The presentation was held for stakeholders from the packaging industry. There is an emerging market of biodegradable plastic. The steady growth rate seems to be governed by capacity development rate, raw material availability, but also customer awareness and new products into the established waste management systems. Geir Kristian Johnsen's presentation includes following issues: Drivers for biodegradables and emerging applications, Waste management issues for biodegradable plastics, Properties and performance of biodegradable film, Achieving Biodegradable films, Future technologies for biodegradable packaging. printme	2005