Polymer Service GmbH Merseburg

Merseburg, Germany

Polymer Service GmbH Merseburg

Merseburg, Germany
SEARCH FILTERS
Time filter
Source Type

Schossig M.,Polymer Service GmbH Merseburg | Bierogel C.,Polymer Service GmbH Merseburg | Grellmann W.,Polymer Service GmbH Merseburg | Grellmann W.,Martin Luther University of Halle Wittenberg
Macromolecular Symposia | Year: 2017

For the assessment of the damage kinetics during the instrumented Charpy impact test (ICIT), the acoustic emissions (AEs) were recorded and the transient signal of the acoustic sensor was analyzed with the wavelet transform (WT). Based on the results discussed in this paper, an assessment of the resistance against stable crack initiation of glass fiber reinforced materials with the help of AE measurements under impact conditions is possible. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim


Lach R.,Polymer Service GmbH Merseburg | Frontini P.M.,University of the Sea | Grellmann W.,Polymer Service GmbH Merseburg | Grellmann W.,Martin Luther University of Halle Wittenberg
Macromolecular Symposia | Year: 2017

The plastic constraint factor based on Hill's theory of plasticity is widely used to check the stress state applying the essential-work-of-fracture (EWF) approach to polymers. However, the plastic constraint factor experimentally determined as the ratio of the net section stress in cracked specimens and the yield stress does not match the theoretical predictions of the theory of plasticity because assuming ideal-plastic behaviour for polymer materials does not consider material-specific viscoelastic–viscoplastic effects adequately. Therefore, a correction term for amorphous thermoplastic polymer materials is derived introducing the influence of the material on the plastic constraint factor. This correction term is based on the Williams-Landel-Ferry (WLF) equation for different thermodynamic quantities such as temperature and stress (negative pressure) and the introduction of a glass stress to be comparable to the glass temperature. Analytical calculation of this correction term, taking polycarbonate as an example, is used as a comparison to empirical values in literature for numerous amorphous and semi-crystalline thermoplastic as well as partial-plastically deformable elastomeric polymer materials. It can be concluded that this enhanced Hill's theory is well suited to amorphous polymers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim


Lach R.,Polymer Service GmbH Merseburg | Grellmann W.,Polymer Service GmbH Merseburg | Grellmann W.,Martin Luther University of Halle Wittenberg
Macromolecular Symposia | Year: 2017

The mixed mode brittle fracture (mode I/mode II) of poly(methyl methacrylate) (PMMA) was investigated using single-edge notched tensile (SENT) specimens by applying a mixed mode special loading device which allows varying the loading angle from 0° (pure mode I) to 90° (pure mode II). The experimental results dealing with mixed mode fracture toughness and initial angle of crack propagation are in good agreement with predictions based on a modified criterion of maximum tangential stress (MTS criterion) where non-singular stresses (T stresses) are considered. These additional T stresses are the reason why distinct fracture by normal stress with crazing is always macroscopically observed in PMMA under the selected loading conditions including pure external mode II loading. Therefore, the length of the craze zone, i.e. the process zone, has been determined to be about 0.5 mm independent of the loading angle. It has to be pointed out that the fracture surface morphology should be kept in mind more often in future for assessing the mixed mode fracture mechanics parameters. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim


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.


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.


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.

Loading Polymer Service GmbH Merseburg collaborators
Loading Polymer Service GmbH Merseburg collaborators