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Kroll M.,BASF | Langer B.,Polymer Service GmbH Merseburg | Grellmann W.,Polymer Service GmbH Merseburg | Grellmann W.,Martin Luther University of Halle Wittenberg
Journal of Applied Polymer Science | Year: 2013

To investigate the influence of moisture and EPR-g-MA content on the fracture behavior of glass-fiber reinforced PA6 materials, brittle-to-tough transition temperatures (T btt) were determined. Water absorption was taken into account by conditioning the analyzed materials. Tensile tests could reveal the temperature range of the largest moisture dependence of mechanical properties between 10 and 50°C. J-integral values were used to describe the fracture behavior under conditions of impact load as a function of temperature. The brittle-to-tough transition of reinforced polyamides was found to be less approximate than in unreinforced materials. Two different characteristic temperature points T s and T e were identified, which were the intercept between elastic and elastic-plastic deformation on the one hand and the starting point of dominating stable crack propagation with strong plastic deformation on the other hand. Characteristic brittle-to-tough transition temperatures T btt could be calculated as the arithmetic average of these two points. Copyright © 2012 Wiley Periodicals, Inc.


Nase M.,Hof University of Applied Sciences | Androsch R.,Martin Luther University of Halle Wittenberg | Henning S.,Fraunhofer Institute for Mechanics of Materials | Grellmann W.,Martin Luther University of Halle Wittenberg | Grellmann W.,Polymer Service GmbH Merseburg
Polymer Engineering and Science | Year: 2015

Peel films of blends of low density polyethylene (LDPE) and random isotactic copolymers of butene-1 with either ethylene (iPB-Eth) or propylene (iPB-Prop) were investigated regarding the effect of the copolymer composition on both the Form II mesophase to Form I crystal transformation of the copolymers, and the time-dependent peel behavior of their blends with LDPE in peel films. In general, there is observed a decrease of the peel force with increasing concentration of both ethylene and propylene co-units in random iPB-1 based copolymers and their blends with LDPE, after completion of the Form II to Form I transformation. Thus, to tailor the peel force, either the content of the peel component in the blends, or the concentration of ethylene or propylene co-units in the peel component may be varied. The effect of ethylene co-units in the random copolymers on the peel force is distinctly larger than that of propylene co-units. Parallel to the Form II to Form I transition of butene-1 based copolymers, the peel force decreases with a rate which depends on the copolymer composition. The Form II to Form I transition in iPB-Prop copolymers proceeds distinctly faster than in iPB-Eth copolymers of identical concentration of co-units. © 2014 Society of Plastics Engineers.


Schossig M.,Polymer Service GmbH Merseburg | Illing T.,Valeo Schalter und Sensoren GmbH | Grellmann W.,Polymer Service GmbH Merseburg | Langer B.,Merseburg University of Applied Sciences
Materials Science Forum | Year: 2015

The qualitative and quantitative assessment of the aging behavior of polymers and polymeric products depends on a substantial characterization of the materials properties and is linked to a multi-parametric approach. However, the choice of suitable polymer diagnostics test methods as well as parameters for the characterization of the material behavior are important. The aging of products can be attributed to complex factors and due to the superposition of different factors, the generation of simple relationships is impossible. Important materials for the automotive industry are fiber-reinforced PA6 materials, which can fulfill the requirements related to the mechanical properties like stiffness, strength, toughness as well as other properties. However, the knowledge for the assessment of different climate conditions as well as media on the aging behavior of such materials is not complete. For this reason, it is essential to describe the behavior with a material-physical approach. © (2015) Trans Tech Publications, Switzerland.


Griessbach S.,V.G. Kunststofftechnik GmbH | Lach R.,Polymer Service GmbH Merseburg | Lach R.,Martin Luther University of Halle Wittenberg | Grellmann W.,Polymer Service GmbH Merseburg | Grellmann W.,Martin Luther University of Halle Wittenberg
Polymer Testing | Year: 2010

Industrial practice requires simple, fast and reliable verification of the mechanical properties of the parts within the process of quality assurance. Therefore, it is necessary to investigate the correlations between structural parameters that can be analysed non-destructively, such as density, and mechanical properties. Using the example of PA12, it was possible to show a linear relation between density, that is porosity, and tensile strength as well as impact strength for notched specimens. Furthermore, a linear correlation was found between elongation at break and notched impact strength as a function of the degree of crystallinity. The relevance of enclosed defects is significant for the maximum load of laser sintered parts. The structure-related imperfections that are invisible from outside can now be detected with a newly developed process, the dynamic dye test of laser sintered parts. It benefits from the correlation between colour saturation, porosity and mechanical properties. Therefore, it is possible to detect failures caused by the layer-based fabrication directly on the part. Consequently, the reliability of the laser sintering process is ensured. © 2010 Elsevier Ltd. All rights reserved.


Lach R.,Martin Luther University of Halle Wittenberg | Lach R.,Polymer Service GmbH Merseburg | Schone J.,Polymer Service GmbH Merseburg | Bierogel C.,Martin Luther University of Halle Wittenberg | And 2 more authors.
Macromolecular Symposia | Year: 2012

An innovative cooling and heating device has been successfully applied to an instrumented macrohardness testing machine in close collaboration with the company Zwick/Roell. The prototype allows the local time-dependent analysis of mechanical properties such as Martens hardness and indentation modulus, as well as fracture toughness and creep and relaxation behaviour at temperatures ranging from -100 °C to +100 °C. On the basis of load-indentation depth, load-time or indentation depth-time diagrams, the indentation behaviour as a function of test speed and/or temperature (which has rarely been done for polymers in the macro-range of loading) depending on matrix and materials composition (amorphous/semicrystalline thermoplastics, epoxy resins, micro- and nanocomposites) has been analysed. Martens-hardness, indentation modulus on the one hand and creep compliance and relaxation modulus on the other have been found to be strongly temperature dependent. Adequate methods of indentation fracture mechanics have been enhanced for polymers and applied to determine the fracture toughness of very different polymer-based materials. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Schone J.,Polymer Service GmbH Merseburg | Lach R.,Polymer Service GmbH Merseburg | Bierogel C.,Martin Luther University of Halle Wittenberg | Grellmann W.,Polymer Service GmbH Merseburg | Grellmann W.,Martin Luther University of Halle Wittenberg
Polymer Testing | Year: 2013

The authors introduce a prototype of a recording (depth-sensing) macroindentation testing machine that has been modified and extended with a temperature chamber. This prototype allows the analysis of different hardness values (Martens hardness, indentation hardness, ball indentation hardness, etc.) and the indentation modulus, as well as time-dependent properties such as creep and relaxation of polymers and other materials, in a wide range of temperature (-100 - 100 C). The applicability of the testing machine for fast and less material-consuming determination of the temperature-dependent mechanical properties is illustrated by means of selected amorphous and semicrystalline thermoplastics, i.e., neat (PMMA and PTFE) and reinforced ones (PMMA/silica nanocomposites). © 2013 Elsevier Ltd. All rights reserved.


Le H.H.,Martin Luther University of Halle Wittenberg | Ilisch S.,Martin Luther University of Halle Wittenberg | Heidenreich D.,Martin Luther University of Halle Wittenberg | Wutzler A.,Polymer Service Merseburg GmbH | Radusch H.-J.,Martin Luther University of Halle Wittenberg
Polymer Composites | Year: 2010

The Fourier transformed infrared (FTIR) spectroscopy on the rubber-filler gel has been used as a tool for the quantitative characterization of the phase selective silica localization in styrene butadiene rubber (SBR)/natural rubber (NR) blends. The so-called rubber-layer L was introduced to describe the selective wetting behavior of the rubber phases to the filler. SBR/NR blends filled with silica were the focus of the experimental investigation. NR shows a higher wetting rate than SBR. Silane addition does not affect the wetting of NR but slowdowns the wetting of SBR. With increasing chamber temperature the value of the rubber-layer L of all mixtures increases owing to the different thermal activated rubber-filler bonding processes. Using the wetting concept the kinetics of silica localization in the phases of heterogeneous rubber blends was characterized. Because of the higher wetting rate of the NR component, in the first stage of mixing of NR/SBR blends more silica is found in the NR phase than in the SBR phase. In the next stage, silica is transferred from the NR phase to the SBR phase until the loosely bonded components of NR rubber-layer are fully replaced by SBR molecules. © 2010 Society of Plastics Engineers.


Kolesov I.,Martin Luther University of Halle Wittenberg | Dolynchuk O.,Martin Luther University of Halle Wittenberg | Borreck S.,Polymer Service GmbH Merseburg | Radusch H.-J.,Martin Luther University of Halle Wittenberg
Polymers for Advanced Technologies | Year: 2014

The capability of phase morphology of covalent networks on the basis of crystallizable polymer blends to control their multiple shape-memory (SM) behavior was proven, especially for invertible two-way SM effect, which is observed as an anomalous elongation of a sample under constant load during the non-isothermal crystallization. In order to achieve a triple-shape one- and two-way behavior, a set of binary blends with different contents of high-density polyethylene and poly(ε-caprolactone) and one 50/50 blend of ethylene-octene copolymer and trans-polyoctenamer cross-linked by peroxide were prepared. The considerable enthalpic effects in temperature ranges of crystallization and melting of both blend components point to possible softening/hardening of discussed blends caused by non-isothermal melting/crystallization at heating/cooling, respectively. The two-way SM behavior was investigated in tensile mode under constant load during cooling and heating sequentially. It is quite obvious that the distinct manifestation of triple-SM behavior is possible only when a continuous phase of blend has lower crystallization/melting temperatures in comparison with dispersed phase. By contrast, if crystallization/melting temperatures of dispersed phase are lower, then its ability to change a shape is suppressed by already solidified continuous phase. Obtained results allow conclude the following: first, the performances of both one- and two-way SME are enhanced with increasing cross-link density and crystallinity of polymer network as well as due to selection of optimal load; second, the key to improve the multiple SM behavior of polymer blends is further optimization of their phase morphology, especially better separation/decoupling of blend phases. © 2014 John Wiley & Sons, Ltd.


Monami A.,Polymer Service GmbH Merseburg | Reincke K.,Martin Luther University of Halle Wittenberg | Grellmann W.,Martin Luther University of Halle Wittenberg | Kretzschmar B.,Leibniz Institute of Polymer Research
Journal of Applied Polymer Science | Year: 2013

The aim of this work was to characterize the fracture behavior of polyamide 6 (PA6) and PA6 reinforced with clay (organically modified montmorillonite) [PA6/OMMT] at different temperatures and under higher loading rate. Pure PA6 and PA6 with different amounts and two types of OMMT were investigated. The structure and morphology of the nanocomposites were analyzed by X-ray diffraction technique and transmission electron microscopy. The fracture behavior was evaluated using the instrumented Charpy impact test at different temperatures starting from -30 °C up to 50 °C. To determine the fracture toughness KId at higher temperatures, the equivalent-energy concept was used. Based on the J-value versus temperature diagrams, the brittle-to-tough transition temperature TBTT of the materials was determined. It was found that the crack toughness as a function of temperature and the T BTT are influenced by the content of OMMT and the morphology. There are indications that at low OMMT contents, the deformation behavior is dominated by the matrix properties. With increasing filler content, the influence of the nanostructure on TBTT increases. The crack toughness of the nanocomposites with an intercalated morphology is higher than that of exfoliated ones, due to additional energy-dissipating mechanisms. © 2012 Wiley Periodicals, Inc.


Nase M.,ORBITA FILM GmbH | Nase M.,Polymer Service GmbH Merseburg | Funari S.S.,German Electron Synchrotron | Michler G.H.,Martin Luther University of Halle Wittenberg | And 4 more authors.
Polymer Engineering and Science | Year: 2010

The structure of blown films of blends of low-density polyethylene (PE-LD) and isotactic polybutene-1 (iPB-1) with different content of iPB-1 was investigated using wide- and small-angle X-ray scattering (WAXS and SAXS), transmission electron microscopy (TEM), and polarizing optical microscopy (POM). TEM proves formation of a matrix-particle phase structure due to immiscibility of the blend components. Within the iPB-1 particles, needle-like crystals with c-axis orientation were observed. The PE-LD matrix showed two populations of crystals. WAXS data indicate that the majority of crystals were oriented with the c-axis perpendicular to machine direction (MD), while SAXS data prove additional presence of stacks of lamellae, oriented parallel to MD. Quantitative birefringence measurements showed that the majority of molecule segments were oriented in the direction of the circumference of the film, confirming the WAXS data. The crystal orientation has direct impact on mechanical properties, which was demonstrated by measurement of the anisotropy of the modulus of elasticity. POLYM. ENG. SCI., 50:249-256, 2010. Copyright © 2009 Society of Plastics Engineers.

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