Würzburg, Germany
Würzburg, Germany

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Horlemann S.,SKZ Das Kunststoff Zentrum | Kraus E.,SKZ Das Kunststoff Zentrum | Baudrit B.,SKZ Das Kunststoff Zentrum | Bastian M.,SKZ Das Kunststoff Zentrum | And 3 more authors.
KGK Kautschuk Gummi Kunststoffe | Year: 2015

The mechanical behavior of bonded PEEK joints was investigated in-situ by means of computed tomography. From the data, the multi-axial strain distribution was analyzed for a tensile shear test of the entire adhesive joint as well as locally in the adhesive layer. For two different loads, the deformation and the overall distortion of the bonded specimen were analyzed in the joining plane during a tensile shear test and compared to simulations.


Wilk R.,Menlo Systems GmbH | Hochrein T.,SKZ Das Kunststoff Zentrum | Blumel L.,Menlo Systems GmbH | Mei M.,Menlo Systems GmbH | Holzwarth R.,Menlo Systems GmbH
IRMMW-THz 2011 - 36th International Conference on Infrared, Millimeter, and Terahertz Waves | Year: 2011

In this paper we present an all-fiber THz spectrometer based on the OSCAT technique. We investigate its application to non-destructive testing in the polymer industry and analyze a set of polymer samples with different contents of TiO2 as a filler. © 2011 IEEE.


Wilk R.,Menlo Systems GmbH | Kocur S.,Menlo Systems GmbH | Hochrein T.,SKZ Das Kunststoff Zentrum | Mei M.,Menlo Systems GmbH | Holzwarth R.,Menlo Systems GmbH
IRMMW-THz 2011 - 36th International Conference on Infrared, Millimeter, and Terahertz Waves | Year: 2011

We present a novel THz imaging system based on an all-fiber THz-OSCAT spectrometer. First THz-OSCAT images are presented and properties of the system, as well its limitations are extensively discussed. © 2011 IEEE.


Probst T.,University of Marburg | Busch S.F.,University of Marburg | Kraus E.,SKZ Das Kunststoff Zentrum | Baudrit B.,SKZ Das Kunststoff Zentrum | And 2 more authors.
International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz | Year: 2013

We present a novel THz-TDS system used for the identification of defects in joint plastic. The system utilizes two delay lines, one long, for defect location and the other short, for imaging of the defect. Cross-sectional THz images that reveal defects (air gaps) are been confirmed using CT measurements. © 2013 IEEE.


Wichmann M.,University of Marburg | Mondol A.S.,University of Marburg | Mondol A.S.,Rhine-Waal University of Applied Sciences | Kocic N.,SKZ Das Kunststoff Zentrum | And 9 more authors.
Applied Optics | Year: 2013

We present terahertz (THz) lenses made of highly refracting polymeric compounds which provide a better focusing performance and an increased functionality in comparison to conventional THz lenses. Using mixtures consisting of polypropylene (PP) and alumina as well as PP and zinc sulfide allows a significant increase of the refractive index while simultaneously keeping a low extinction and dispersion. With these new material combinations, lenses with an increased focusing capability are realized. This is evaluated by focal plane measurements using a fiber coupled THz time-domain spectrometer © 2013 Optical Society of America.


Achereiner F.,SKZ Das Kunststoff Zentrum | Engelsing K.,SKZ Das Kunststoff Zentrum | Bastian M.,SKZ Das Kunststoff Zentrum | Heidemeyer P.,SKZ Das Kunststoff Zentrum
Polymer Testing | Year: 2013

The increasing use of polymers in engineering applications requires suitable accelerated test methods for predicting their long-term behavior. The stepped isothermal method (SIM), originally developed for product testing of geosynthetics, was successfully applied in the presented work to characterize the long-term creep behavior of polypropylene up to approximately 100 years. Based on the time-temperature superposition principle, this method can be described as a short-term creep experiment during which the temperature is elevated stepwise. It is shown that the temperature steps can be rescaled and shifted to generate a master curve matching the prediction of long-term creep resulting from the conventional approach of the time-temperature superposition principle (TTSP). This compliance with established test methods and its good reproducibility suggests that SIM might be a useful tool for accelerated testing of long-term creep behavior, especially for comparative purposes such as quick screening of material formulations during the early development stages, or the at-line assessment of resins as part of quality assurance. © 2013 Elsevier Ltd. All rights reserved.


Damodaran S.,Fraunhofer Institute for Structural Durability and System Reliability | Schuster T.,Fraunhofer Institute for Structural Durability and System Reliability | Rode K.,Fraunhofer Institute for Structural Durability and System Reliability | Sanoria A.,Fraunhofer Institute for Structural Durability and System Reliability | And 2 more authors.
Polymer (United Kingdom) | Year: 2015

The superstructures developed in the welds between injection molded plates made from α-nucleated and non-nucleated isotactic polypropylene (iPP) were analyzed by infrared (IR) microscopy, polarized light microscopy (PLM) and differential scanning calorimetry (DSC). Layers of distinct structures and size formed during welding in the welds were identified by PLM. Deformation of spherulites occurred in the weld seams due to the sheared melt flow. The orientation of the polymer chains in the welds, which is the result of melting and recrystallization, was quantified by IR microscopy for the first time: In the injection molded plates the chains were oriented along machine direction (MD), whereas this pattern changed to normal direction (ND) at the weld seams. Two positions at the welds were inspected to study the orientation of the chains: In one of these the PLM image depicts two well defined weld seams, while at the other, the weld seams were absent. DSC analysis of microtomed sections revealed the presence of both iPP polymorphs in the injection molded plates, whereas in the weld seam and weld core the α- and β-phase, respectively, were found. The degree of crystallinity (Xc) of the welds of iPP calculated using DSC and IR microscopy showed a homogeneous profile across the welds. The antioxidants (AOs) and the nucleating agent were profiled across the weld using IR-microscopy. A significant consumption of AOs during welding could be shown, and, using the principle of IR-dichroism, thermo-oxidative degradation of iPP chains was observed, even in the presence of AOs. The nucleating agent was homogeneously distributed across the weld. © 2015 Elsevier Ltd.


Kocic N.,SKZ Das Kunststoff Zentrum | Kretschmer K.,SKZ Das Kunststoff Zentrum | Bastian M.,SKZ Das Kunststoff Zentrum | Heidemeyer P.,SKZ Das Kunststoff Zentrum
Journal of Applied Polymer Science | Year: 2012

A new method is proposed, which can be used to analyze the influence of different additives and fillers on the nonisothermal crystallization of polymers. The composites of talc in isotactic polypropylene (i-PP) were prepared using a corotating twin-screw extruder. The compounds were subsequently dried and injection molded. PP morphology and talc dispersion were visualized using optical microscopy and computed tomography. Wide-angle X-ray scattering and small-angle X-ray scattering measurements provided an insight into the crystal structure of PP. The data obtained from nonisothermal DSC measurements were fitted to the Avrami model for the nonisothermal case. The calculated Avrami's exponent (n), which takes into account the influence of talc on the nucleation and growth of the PP crystals, was used in the combination of Lauritzen-Hoffman and Ozawa models to calculate the nucleation parameter (K g). A good agreement was found between the model predictions and literature values. The examination shows that the developed model extension gives an expected trend in the case of i-PP filled with talcs from the same origin but with different particle sizes. Furthermore, it is shown that delaminated talc with a higher specific surface is more efficient in nucleation of i-PP. Thus, the introduced model extension could be a useful tool for comparing of nucleation ability of different additives in the crystallization of polymers. © 2012 Wiley Periodicals, Inc.


Deubel C.,SKZ das Kunststoff Zentrum | Schwalme G.,SKZ das Kunststoff Zentrum | Schink K.,SKZ das Kunststoff Zentrum | Bastian M.,SKZ das Kunststoff Zentrum | Heidemeyer P.,SKZ das Kunststoff Zentrum
Kunststoffe International | Year: 2012

Thermoplastic elastomers (TPE) are a versatile class of materials. Their chemical and physical properties range between those of the hard uncross-linked thermoplastics and those of extensible cross-linked elastomers. The processing of thermoplastic elastomers is always a challenge. Each class of TPE, and often each grade, imposes its own requirements for a robust, fully automated production process. Adhesion or the formation of adhesion mechanisms between the hard and soft components is critically dependent on the contact temperature when the TPE is injected over or onto the thermoplastic. The mold and three test arrangements were tested and optimized with over 20 combinations of materials drawn from the TPE classes TPE-S,TPE-V,TPE-E and TPE-U. Measurement and possibly regulation of the temperature-control system are usually performed by temperature sensors in the mold.


Baudrit B.,SKZ Das Kunststoff Zentrum | Bogdanovic M.,SKZ Das Kunststoff Zentrum | Hoffmann M.,SKZ Das Kunststoff Zentrum | Heidemeyer P.,SKZ Das Kunststoff Zentrum | Bastian M.,SKZ Das Kunststoff Zentrum
Kunststoffe International | Year: 2011

Detailed studies into the weldability of high-filler wood fiber-reinforced plastic composites (WPC) using different methods have shown that the fiber orientation in the joining plane and the actual composite formulation have a key impact on the strength of a weld seam. The welding factors achieved of up to 0.8 allow the conclusion to be drawn that this joining method can be used for several new products and fields of application. Material binding techniques, such as welding are being increasingly used along with the conventional techniques to extend the geometries and complexities of WPC products. The choice of WPC profiles to be made under these studies has been made under material-specific and geometric aspects.

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