Scientific publications

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Title	Year
Technical performance of biodegradable polymers as compared to polyolefins 2012, Markus Gahleitner, Petar Doshev. Technical performance of biodegradable polymers as compared to polyolefins BiPoCo – International Conference on Bio-based Polymers and Composites, Síofok / HU – 28.-31.05.2012, - (-), 2012, - The present public discussion of plastics is focusing mostly on the supposed problems generated by the presently widely applied materials and seems to assume that these can be substituted rapidly by biodegradable and/or bio-based polymers, if not by paper or other “traditional” materials. Largely neglected in this discussion are the technical limitations of biobased polymers which could easily turn out to be a permanent limitation to their applicability. Using a number of present polyolefin applications from the packaging sector to technical uses the inherent problems of most of the now discussed materials like poly(lactic acid) (PLA), poly(hydroxyl alkanoate) (PHA) and thermoplastic starch compositions (TPS) in comparison to polyethylene (PE) and polypropylene (PP) are outlined. printme	2012
HeCos for the Automotive Industry: Basic Correlations between EPR-Design and Shrinkage 2012, Gregory Potter, Georg Grestenberger, Christelle Grein, Cornelia Kock. HeCos for the Automotive Industry: Basic Correlations between EPR-Design and Shrinkage PPS Americas Conference, Niagara Falls / CD, 21-24 May 2012, - (-), 2012, - The influence of the morphology on the shrinkage of heterophasic copolymers (HeCos) was investigated using a model series. The morphology of the dispersed phase, in terms of size and shape of the rubber particles, was found to correlate fairly well with the shrinkage determined in the flow and transverse direction of injection moulded samples. Additionally, the effect of the EPR design on the coefficient of linear thermal expansion (CLTE) has been evaluated. printme	2012
Ultra-Rigid Metallocenes for Highly Iso- and Regiospecific Polymerization of Propene: The Search for the Perfect Polypropylene Helix 2012, Alexander Schoebel, Eberhardt Herdtweck, Matthew Parkinson, Bernhard Rieger. Ultra-Rigid Metallocenes for Highly Iso- and Regiospecific Polymerization of Propene: The Search for the Perfect Polypropylene Helix Chem.Eur.J., 18 (-), 2012, 4174-4178 A new class of metallocenes for reaching high chain regularity in isotactic PP is presented. printme	2012
Clarifiers from sustainable source: application and performance in polypropylene 2012, Jingbo Wang. Clarifiers from sustainable source: application and performance in polypropylene S-PolyMat 2012 - Sustainability in Polymer Materials, Kerkrade, NL, 20.-23.05.2012, - (-), 2012, - Polypropylene and poly(propylene-ethylene) random copolymers are widely used in the industry and daily life, because of its good balance between the performance and cost. However, its translucent nature limits the applications in some fields (i.e. food package), where high transparency is required. The clarifiers (mainly sorbitol based compounds, i.e. Millad 3988) are widely used at the present time, but they decompose during processing and render final products odour. In addition, the preparation of the clarifier relies on the modern petro-chemistry. Here we provide a new synthetic route for the clarifier which i) has good stability and good performance; ii) the raw materials is from sustainable sources (i.e. nature products). The transparent PP is prepared by extrusion of PP with dehydroabietic acid (DHA) and sodium stearate (NaSt), the clarifier forms by in-situ reaction of DHA and NaSt during extrusion, which eliminates the synthetic process and the pollution and reduces the energy consumption. printme	2012
Mechanical and optical effects of elastomer interaction in polypropylene modification: Ethylene-propylene rubber, poly-(ethylene-co-octene) and styrene-butadiene elastomers 2012, Christelle Grein, Markus Gahleitner, Klaus Bernreitner. Mechanical and optical effects of elastomer interaction in polypropylene modification: Ethylene-propylene rubber, poly-(ethylene-co-octene) and styrene-butadiene elastomers eXPR.Polym.Lett., 6 (9), 2012, 688-696 The interaction between binary combinations of three different elastomer classes commonly applied in impact modification of isotactic polypropylene (iPP) was studied. Blends based on a homogeneous ethylene-propylene (EP) random copolymer (EP-RACO) and a heterophasic EP impact copolymer comprising ethylene-propylene rubber (EPR) with different external elastomer types, one homogeneous ethylene-1-octene copolymer (EOC), and two hydrogenated styrene-butadiene-styrene triblock copolymers (SEBS) with different styrene content, were prepared. The phase morphology, mobility as a function of temperature, mechanical and optical properties were studied. Special effects could be achieved for the combination of two different elastomer types. The results clearly demonstrate the possibility to achieve attractive property combinations in ternary systems consisting of a crystalline PP matrix and two different types of elastomer, EPR or EOC on the one hand and SEBS on the other hand. A combination of density matching and compatibilization effects allows reaching good low temperature impact strength together with a transparency close to matrix level when selecting a butadiene-rich SEBS type. printme	2012
Structural Polymeric Materials - Ageing Behavior of Solar Absorber Materials 2012, Susanne Kahlen, Gernot Wallner, Reinhold W. Lang. Structural Polymeric Materials - Ageing Behavior of Solar Absorber Materials M. Köhl et al. (Eds.), Polymeric Materials for Solar Thermal Applications, Wiley-VCH, Weinheim 2012, - (-), 2012, 243-253 The Ageing behaviour of lightweight polymeric materials as alternatives to metals for solar absorbers has been studied. printme	2012
Azobenzene isomerization in polymer co-crystalline phases 2012, Alexandra R. Albunia, Paola Rizzo, Maria Coppola, Martina De Pascale, Gaetano Guerra. Azobenzene isomerization in polymer co-crystalline phases Polymer, 53 (-), 2012, 2727-2735 Three different co-crystalline phases of syndiotactic polystyrene (s-PS) with azobenzene have been prepared and structurally characterized. The triclinic d-clathrate phase is characterized by a styrenemonomeric- unit/guest ratio (SU/G) equal to 8/1 while the d-intercalate phase is characterized by SU/ G = 4/1. The orthorhombic ε-clathrate phase allows stacking of a variable number of guest molecules per monomer unit with SU/G = 9/1. Isomerization reactions of the azobenzene guest molecules (both photoinduced trans / cis and spontaneous cis / trans) have been studied by UVeVisible and FTIR measurements. Repeated isomerization cycles produce progressive desorption from the polymer film of azobenzene molecules being simply dissolved in s-PS amorphous phases, while poorly affect the content of azobenzene molecules being guest of s-PS co-crystalline phases. Polarized FTIR spectra of axially oriented films indicate that isomerizations occur without expulsion of azobenzene guest molecules from the polymer co-crystalline phases. The whole set of data indicate that films exhibiting co-crystalline phases of azobenzene with s-PS are suitable for producing self-erasing photo-isomerization patterns with molecular size marks. printme	2012
Infrared Linear Dichroism as a Tool to Evaluate Volatile Guest Partition Between Amorphous and Nanoporous-Crystalline Polymer Phases 2012, Alexandra R. Albunia, Vincenzo Venditto, Gaetano Guerra. Infrared Linear Dichroism as a Tool to Evaluate Volatile Guest Partition Between Amorphous and Nanoporous-Crystalline Polymer Phases J.Polym.Sci.B:Polymer Physics, 50 (-), 2012, 1474–1479 Desorption kinetics of ethene, propene, and butadiene from films exhibiting axially oriented nanoporous-crystalline δ phases of syndiotactic polystyrene (s-PS) have been followed by gravimetric and infrared linear dichroism measurements. The reported data can be rationalized by assuming that, after the initial desorption mainly involving molecules absorbed in the amorphous phase, most gaseous molecules are included as guest in the nanoporous-crystalline phase. This allows establishing a simple method to evaluate guest partition between nanoporous-crystalline and amorphous polymeric phases, which possibly can be applied for most volatile guest molecules. The described method also allows establishing the presence of one guest molecule (ethene, propene, or butadiene) per cavity of the nanoporous δ form. printme	2012
Modeling of the nonlinear viscoelasticity of polyoxymethylene in tension and compression 2012, Simon Gastl, D. Tscharnuter, Gernot Pinter. Modeling of the nonlinear viscoelasticity of polyoxymethylene in tension and compression International Journal of Engineering Science, 60 (-), 2012, 37–52 An optical measurement technique was used to measure the axial and transverse strain of polyoxymethylene in various uniaxial tensile and compressive loadings. The 3d nonlinear viscoelastic model of Schapery was chosen to describe the time-dependent mechanical behavior. The model equation is solved using a recursive technique, which is used in a nonlinear optimization algorithm to identify model parameters by fitting experimental data. It is shown that the Schapery model is capable of describing the nonlinear viscoelastic relaxation behavior in tension and compression. Furthermore, it is verified that the model determined using stress relaxation data can accurately predict the response to creep and cyclic stress histories. A bending stress relaxation test serves as an exemplary test of a structure with simultaneously occurring compressive and tensile stresses. The model is used in a finite-element simulation of this test to demonstrate its performance in this more complex application. printme	2012
High impact polypropylenes with high melt strength 2012, Markus Gahleitner, Tung Pham, Klaus Bernreitner. High impact polypropylenes with high melt strength IRC 2012 – XVIth International Congress on Rheology – Lisbon / PT, 05.08.-10.08.2012, - (-), 2012, - The reactive modification of polypropylene homopolymers and ethylene-propylene random copolymers with a combination of peroxide and a diene as coupling agent allows the production of long-chain branched PPs with high melt strength (HMS-PP). With these polymers some conversion processes like foaming and extrusion coating (for which linear polymers are unsuitable) become accessible, while others like deep thermoforming and high volume extrusion blow moulding are facilitated. When an analogous process is applied to heterophasic ethylene-propylene impactcopolymers a modification of the interface between matrix and rubber phase is generated rather than branches, making “high-impact HMS-PP” inaccessible via this route. Twoconcepts for combining melt strength and toughness are known in the literature: - Combining linear PP homopolymers and long-chain branched low density polyethylene (LDPE) as done for foaming and extrusion coating before the development of HMS-PP; these materials have limited impact strength because of poor compatibility - Blends of HMS-PP homopolymers with EP impact copolymers in which impact strength is improved at the cost of a reduced melt strength Ternary blends of EP impact copolymers with HMS-PP homopolymers and LDPE have been found capable of delivering the required property combination which can be tuned in a wide range. The linear (dynamic shear) and nonlinear (extensional) rheology of these systems is compared to the phase morphology and the resulting mechanical performance. Possibilities and limitations of mixing rules are clearly related to the branching structure and the particle size of the dispersed elastomer and PE phase. printme	2012