Suddeutsches Kunststoff Zentrum SKZ

Würzburg, Germany

Suddeutsches Kunststoff Zentrum SKZ

Würzburg, Germany
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Maria R.,German Institute for Polymers DKI | Rode K.,German Institute for Polymers DKI | Brull R.,German Institute for Polymers DKI | Dorbath F.,Suddeutsches Kunststoff Zentrum SKZ | And 3 more authors.
Polymer Degradation and Stability | Year: 2011

Plastic pipes are often exposed to a range of environmental conditions which may lead to their degradation. The most important influence factors are UV radiation, humidity and temperature. These can cause leaching of long-term and light stabilisers and finally oxidation of the polymer. In this study we demonstrate how the elemental steps of the photooxidative degradation of polyethylene pipes can be monitored by IR-microscopy. In detail the influence of UV radiation leads to a depletion of the phenolic long-term stabiliser, Irganox 1010. Calibration of the spectroscopic data enables IR-microscopy to be carried out in a quantitative manner and the rate constants for the stabiliser loss to be calculated for the first time. The results obtained from IR-microscopy are well in agreement with those obtained by mechanical sample preparation and measurement of the oxidative induction time (OIT) as well as extraction coupled with chromatographic analysis (HPLC). A mechanism based on Norrish type cleavage is proposed. Also the formation of trans-vinylidene groups as unsaturated degradation products of the PE can be observed. In summary it can be shown that IR-microscopy is highly superior to the conventional approach of mechanical sample preparation with regard to spatial resolution and offers the advantage of being less labour intensive. © 2011 Elsevier Ltd. All rights reserved.


Wietzke S.,University of Marburg | Jansen C.,University of Marburg | Reuter M.,University of Marburg | Jung T.,University of Marburg | And 4 more authors.
Journal of Molecular Structure | Year: 2011

Polymers typically show only low absorption in the far-infrared or terahertz (THz) frequency range and are thus often used as window or lens materials for THz spectroscopy and imaging systems. A comprehensive study of the far-infrared properties of polymers yet reveals that THz spectroscopy is a very convenient technology for the investigation of various material properties including the morphology. Here, we report the dielectric parameters refraction index n and absorption coefficient κ of various polymers determined by THz time-domain spectroscopy with a very high precision. The observed features are attributed to macromolecular origin. Furthermore, we show that the temperature-dependent lattice mode shifts of highly-crystalline polymers reveal information about thermo-morphological interactions between the amorphous and the crystalline phase. A temperature-dependent refractometric data base of various standard polymers completes the paper. This data base enables the determination of the glass transition temperature T g of these polymers and allows the extrapolation of the index of refraction across a broad range of temperatures above and below T g for a given material. © 2011 Elsevier B.V. All rights reserved.


Jordens C.,TU Braunschweig | Scheller M.,TU Braunschweig | Wietzke S.,TU Braunschweig | Romeike D.,TU Braunschweig | And 5 more authors.
Composites Science and Technology | Year: 2010

We employ terahertz time-domain spectroscopy (THz TDS), a novel, non-destructive testing method, to study the fibre orientation and fibre content in reinforced plastics. The birefringent properties of plastics filled with differing amounts of short glass fibres are measured at frequencies from 100 GHz up to 1 THz. To predict the permittivity of the experimentally examined composite materials, we use an effective medium theory first introduced by Polder and van Santen. On the basis of the measured data and this model, we deduce the additive content ξ, the preferential orientation of the fibres φ and the fraction of orientated fibres a. Our findings agree well with corresponding mold flow simulations performed with commercially available software. © 2009 Elsevier Ltd. All rights reserved.


Brull R.,German Institute for Polymers DKI | Geertz G.,German Institute for Polymers DKI | Maria R.,German Institute for Polymers DKI | Rode K.,German Institute for Polymers DKI | And 5 more authors.
Society of Plastics Engineers - EUROTEC 2011 Conference Proceedings | Year: 2011

The loss of stabilizing additives is a crucial elemental step in the ageing of polymers. However, the approach currently used to determine the spatial distribution of antioxidants in finished or semi-finished products of polymers is extremely limited with regard to spatial resolution and reproducibility. Infrared microscopy offers an extremely powerful alternative with regard to both these criteria: Using infrared microscopy the extraction of the phenolic long term stabilizer Irganox 1010 from the wall of polypropylene pipes can be monitored. Carrying out IR-microscopy in a quantitative manner enables to determine the temperature and pressure dependent diffusion constants of the stabilizer. The same approach also allows to monitor the loss of Irganox 1010 from the surface of polyethylene pipes as a result of weathering. A quantitative relationship between the loss rate and the radiation dose can be established.


Seibert K.,Suddeutsches Kunststoff Zentrum SKZ | Stubs O.,Suddeutsches Kunststoff Zentrum SKZ | Bastian M.,Suddeutsches Kunststoff Zentrum SKZ
Kunststoffe International | Year: 2010

Süddeutsches Kunststoff-Zentrum (SKZ), Germany, investigated sustainability aspects of Wood Polymer Composites (WPCs) as a specimen class of material in order to make a contribution to sustainable development. Life Cycle Management (LCM) was chosen for the analysis and evaluation of WPCs in respect of their sustainability. LCM investigates products through their entire life time, from manufacture and service life through to disposal. The influence of wood content in WPCs on the sustainability of products based on polypropylene was investigated using the evaluation methodology. The environmental factors of energy are described using cumulative energy demand (CED). A further area where more sustainability can be achieved is WPC processing. Environmental impacts and costs in this area can be reduced by the use of energy efficient techniques. Further investigations at the SKZ are planned in particular into the service life in the application as well as other aspects such as recycling from economical and ecological standpoints.

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