TY - JOUR A1 - Schartel, Bernhard A1 - Krüger, Simone A1 - Wachtendorf, Volker A1 - Hennecke, Manfred T1 - Chemiluminescence: A promising new testing method for plastic optical fibers N2 - The thermo-oxidative degradation of a polymeric optical cable is investigated by chemiluminescence, The results are reliable and reproducible. Two distinct processes are reported marked by a peak and a plateau behavior versus the time, respectively. Both processes are ruled by thermally activated processes. Beside the dependencies of temperature and time, the influence of absorbed water is discussed. Chemiluminescence is proposed as a promising candidate for a suitable testing method assessing the thermo-oxidative stability of plastic optical fibers and cables. it requires not more than a simple one-day testing procedure and has the advantage that it can be carried out even within the lo cv temperature ranges of the cables' intended use. KW - Chemiluminescence KW - Chemilumineszenz PY - 1999 DO - https://doi.org/10.1109/50.803022 SN - 0733-8724 SN - 1558-2213 VL - 17 IS - 11 SP - 2291 EP - 2296 PB - Institute of Electrical and Electronics Engineers CY - New York, NY AN - OPUS4-718 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wachtendorf, Volker A1 - Geburtig, Anja T1 - Chemiluminescence for the early detection of weathering effects of coatings - Part II: Experimental set-up and examination KW - Chemiluminescence KW - Weathering KW - Polymer KW - Oxidation PY - 2010 SN - 1547-0083 VL - 7 IS - 5 SP - 38 EP - 44 PB - Federation of Societies for Coatings Technology CY - Blue Bell, Pa. AN - OPUS4-21494 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wachtendorf, Volker A1 - Geburtig, Anja T1 - Chemiluminescence for the early detection of weathering effects of coatings - Part I: Fundamentals KW - Chemiluminescence KW - Weathering KW - Polymer KW - Oxidation PY - 2010 SN - 1547-0083 VL - 7 IS - 4 SP - 66 EP - 71 PB - Federation of Societies for Coatings Technology CY - Blue Bell, Pa. AN - OPUS4-21493 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Appajaiah, Anilkumar A1 - Wachtendorf, Volker A1 - Daum, Werner T1 - Characterization of thermo-oxidative stability of polymer optical fibers using chemiluminescence technique N2 - The thermo-oxidative stability of commercially available polymer optical fibers (POFs) and their components (cores and claddings) was investigated. All the bare POFs (core and cladding only) studied here were based on poly(methyl methacrylate) (PMMA) core. The fibers were exposed to 100 °C/low humidity for about 4200 h. Chemiluminescence (CL) technique was applied to investigate the thermo-oxidative stability and for measuring the transmission loss during exposure a prototype device called multiplexer was used. POFs exhibited variation in thermo-oxidative stability although they possessed identical core material PMMA. This was due to difference in the chemical compositions of claddings. Claddings were more susceptible to the thermo-oxidative degradation compared to cores. The thermo-oxidative degradation of both the cladding and the core was found in POFs as a result of climatic exposure. POFs showed an early drop-off followed by a slow decline of transmission. The early drop-off of transmission was attributed to physical changes like thermal expansion and the slow decline of transmission to chemical changes like oxidative degradation of POFs. A good linear relationship between optical transmission stability and thermo-oxidative stability of POFs was established from these studies. KW - Polymer optical fibers (POFs) KW - Chemiluminescence (CL) KW - Thermo-oxidative stability KW - Aging KW - Optical transmission stability PY - 2006 DO - https://doi.org/10.1016/j.polymdegradstab.2006.05.006 SN - 0141-3910 SN - 1873-2321 VL - 91 IS - 11 SP - 2605 EP - 2613 PB - Applied Science Publ. CY - London AN - OPUS4-13984 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schilling, Markus A1 - Marschall, Niklas A1 - Niebergall, Ute A1 - Wachtendorf, Volker A1 - Böhning, Martin T1 - Characteristics of environmental stress cracking of PE-HD induced by biodiesel and diesel fuels N2 - In the context of the increasing effect of carbon dioxide emissions on the global climate biodiesel produced from renewable sources has emerged as a promising contender replacing fossil fuels, especially in long-range transport vehicles, using existing engines and infrastructure. High-density polyethylene is one of the prevailing materials for pipe and container applications for storage and transport of such fuels, both, from fossil and renewable resources. The contact with the respective fuels raises questions concerning material compatibility as biodiesel exhibits significant differences compared to conventional diesel fuel affecting its sorption and plasticization behavior in polyethylene. In this study, its behavior with respect to environmental stress cracking, considered one of the most frequent damage mechanisms leading to failure of polymer parts and packaging, was evaluated using the well-established Full Notch Creep Test. This approach allows for a detailed fracture surface analysis using imaging techniques, such as optical and laser scanning microscopy, as well as infrared spectroscopy. Comparing the environmental stress cracking behavior in standard surfactant solutions with that in biodiesel and diesel, respective crack propagation rates, showing different levels of acceleration, were determined and details of the underlying mechanisms could be revealed. Furthermore, the specific infrared absorption of the biodiesel’s ester functionality allows its semi-quantitative determination on the fracture surface of the tested specimens after failure. Thus, a preferred uptake of sorptive fluids in the fracture zone due to local morphological changes of the polyethylene could be directly evidenced by infrared spectroscopy. KW - Environmental stress cracking (ESC) KW - Full notch creep test (FNCT) KW - Confocal laser scanning microscopy (LSM) KW - Biodiesel KW - Diesel PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608591 DO - https://doi.org/10.1016/j.polymertesting.2024.108547 SN - 0142-9418 VL - 138 SP - 1 EP - 16 PB - Elsevier Ltd. AN - OPUS4-60859 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scholz, Philipp A1 - Wachtendorf, Volker A1 - Elert, Anna Maria A1 - Falkenhagen, Jana A1 - Becker, Roland A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute A1 - Tschiche, Harald A1 - Reinsch, Stefan A1 - Weidner, Steffen ED - Scholz, Philipp T1 - Analytical toolset to characterize polyurethanes after exposure to artificial weathering under systematically varied moisture conditions N2 - Polyether and -ester urethanes (PU) were exposed to artificial weathering at 40 °C and artificial UV radiation in a weathering chamber. In 3 parallel exposures, humidity was varied between dry, humid, and wet conditions. Material alteration was investigated by various analytical techniques like size exclusion chromatography (SEC), liquid chromatography-infrared spectroscopy (LC-FTIR), thermal-desorption gas chromatography-mass spectrometry (TD-GC-MS), fluorescence mapping and dynamic mechanical analysis (DMA). Our results show that depending on the weathering conditions, different degradation effects can be observed. By means of SEC an initial strong decrease of the molar masses and a broadening of the mass distributions was found. After a material dependent time span this was followed by a plateau where molar mass changes were less significant. A minor moisture-dependent degradation effect was only found for polyester PU. Fluorescence measurements on two materials revealed an increase in the luminescence intensity upon weathering process reaching a saturation level after about 500 h. The changes in the optical properties observed after different exposure conditions and times were very similar. The TD-GC-MS data showed the fate of the stabilizers and antioxidant in the course of weathering. LC-FTIR measurements revealed a change in peak intensities and the ratio of urethane and carbonyl bands. KW - Polyurethane KW - Artificial weathering KW - Moisture KW - Crosslinking KW - Degradation PY - 2019 UR - https://www.sciencedirect.com/science/article/pii/S0142941819303708 DO - https://doi.org/10.1016/j.polymertesting.2019.105996 SN - 0142-9418 VL - 78 SP - 105996, 1 EP - 9 PB - Elsevier CY - Amsterdam AN - OPUS4-48625 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Simone A1 - Brademann-Jock, Kerstin A1 - Wachtendorf, Volker A1 - Rauth, W. A1 - Klimmasch, T. A1 - Krüger, P. T1 - Analysis of weathering effects in automotive coatings by thermoluminescence KW - Automotive coatings KW - Weathering KW - Thermoluminescence PY - 2006 SN - 0048-4225 N1 - Sprachen: Englisch/Italienisch - Languages: English/Italian VL - 82 IS - 17 SP - 5 EP - 11 AN - OPUS4-14296 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wachtendorf, Volker A1 - Geburtig, Anja T1 - Alterungseffekte bei Polymerwerkstoffen messen N2 - Bei der Auswahl von Werkstoffen spielt deren Alterung oft eine untergeordnete Rolle, stattdessen wird häufig der ungealterte Ausgangszustand optimiert. Materialien altern aber unterschiedlich. Der Effekt der molekularen Alterung spiegelt sich in den Eigenschaften mehr oder weniger stark und in unterschiedlichem zeitlichen Verlauf wider. Da es kein physikalisch-chemisches Modell dafür gibt, sind Alterungseffekte empirisch zu bestimmen. KW - Alterung KW - Polymerwerkstoff KW - Eigenschaftsänderung PY - 2012 DO - https://doi.org/10.1002/nadc.201290356 SN - 1439-9598 SN - 1521-3854 VL - 60 IS - 10 SP - 1018 EP - 1022 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-26666 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Metz, Christian A1 - Franz, Philipp A1 - Fischer, C. A1 - Wachtendorf, Volker A1 - Maierhofer, Christiane T1 - Active thermography for quality assurance of 3D-printed polymer structures N2 - Additively manufactured test specimens made of polyamide 12 (PA 12) by Laser Sintering as well as of acrylonitrile butadiene styrene (ABS) by Fused Layer Modelling, were characterised with active thermography directly after manufacturing and after artificial weathering. For this, two different excitation methods (flash and pulse heating) were used and compared, regarding their suitability for the detection of constructed and imprinted defects inside the test specimens. To increase the quality of the thermograms, data processing methods like thermal signal reconstruction (TSR) and Fourier Transformation after TSR were applied. To further investigate the long-term stability of the additively manufactured test specimens towards environmental stress, like UV radiation, heat, humidity, water contact and frost with active thermography, an artificial weathering test over 2000 hours (~3 months) was applied to the specimens. The monitoring of the changes in the optical properties of the weathered plastics was supplemented by spectral reflectance and UV/VIS spectroscopy. KW - Additive manufacturing KW - Polymers KW - Artificial weathering KW - Active thermography KW - UV/VIS spectroscopy PY - 2019 DO - https://doi.org/10.1080/17686733.2019.1686896 SN - 1768-6733 (Print) 2116-7176 (Online) VL - 18 IS - 1 SP - 50 EP - 72 PB - Taylor & Francis AN - OPUS4-49817 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Geburtig, Anja A1 - Wachtendorf, Volker A1 - Trubiroha, Peter T1 - Accelerated weathering test for plastics and coatings that are exposed to acidic precipitation N2 - Due to the occurrence of acidic precipitation, and due to the fact that polymers and stabilizers may be sensititve to acids, it is important to have a laboratory test that combines weathering exposure with acidic exposure. The loss of stabilization caused by an acid damage of stabilizing system gets evident only over the weathering progress. For solid samples, for wich mostly the surface properties are relevant, the "Acid Dew and Fog Test" (ADF test) was established. For woven or tufted materials, the "Acid Rain Test" (AR test) was developed. The proposed weathering tests aim at plastics as well as at coatings. T2 - 7th International Symposium on Weatherability (7th ISW) CY - Kanagawa, Japan DA - 2008-10-23 KW - Acid rain KW - ADF KW - Acid Dew and Fog test KW - Artificial Weathering test PY - 2009 SN - 1346-0633 VL - 21 IS - 2 SP - 69 EP - 73 PB - Materiaru-Raifu-Gakkai CY - Tokyo AN - OPUS4-18270 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Milks, A. A1 - Lehmann, J. A1 - Leder, D. A1 - Sietz, M. A1 - Koddenberg, T. A1 - Böhner, U. A1 - Wachtendorf, Volker A1 - Terberger, T. T1 - A double-pointed wooden throwing stick from Schöningen, Germany: Results and new insights from a multianalytical study N2 - The site of Schöningen (Germany), dated to ca. 300,000 years ago, yielded the earliest large-scale record of humanly-made wooden tools. These include wooden spears and shorter double-pointed sticks, discovered in association with herbivores that were hunted and butchered along a lakeshore. Wooden tools have not been systematically analysed to the same standard as other Palaeolithic technologies, such as lithic or bone tools. Our multianalytical study includes micro-CT scanning, 3-dimensional microscopy, and Fourier transform infrared spectroscopy, supporting a systematic technological and taphonomic analysis, thus setting a new standard for wooden tool analysis. In illustrating the biography of one of Schöningen’s double-pointed sticks, we demonstrate new human behaviours for this time period, including sophisticated woodworking techniques. The hominins selected a spruce branch which they then debarked and shaped into an aerodynamic and ergonomic tool. They likely seasoned the wood to avoid cracking and warping. After a long period of use, it was probably lost while hunting, and was then rapidly buried in mud. Taphonomic alterations include damage from trampling, fungal attack, root damage and compression. Through our detailed analysis we show that Middle Pleistocene humans had a rich awareness of raw material properties, and possessed sophisticated woodworking skills. Alongside new detailed morphometrics of the object, an ethnographic review supports a primary function as a throwing stick for hunting, indicating potential hunting strategies and social contexts including for communal hunts involving children. The Schöningen throwing sticks may have been used to strategically disadvantage larger ungulates, potentially from distances of up to 30 metres. They also demonstrate that the hominins were technologically capable of capturing smaller fast prey and avian fauna, a behaviour evidenced at contemporaneous Middle Pleistocene archaeological sites. KW - FTIR KW - Stone Age KW - Middle Pleistocene KW - Throwing-stick KW - Wood KW - Micro-CT scanning KW - 3-dimensional microscopy PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-580012 DO - https://doi.org/10.1371/journal.pone.0287719 SN - 1932-6203 VL - 18 IS - 7 SP - 1 EP - 32 PB - PLOS CY - San Francisco, California, US AN - OPUS4-58001 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ramanujam, Maalolan A1 - Wachtendorf, Volker A1 - Purohit, Purv A1 - Mix, Renate A1 - Schönhals, Andreas A1 - Friedrich, Jörg Florian T1 - A detailed dielectric relaxation spectroscopy study of artificial UV weathered low density polyethylene N2 - Artificial weathering of LDPE under dry conditions (<10% of relative humidity) by UV radiation was monitored by dielectric spectroscopy. For an apolar polymer like LDPE, dielectric study yields Information about the change in structure and dynamics of the system. The fluctuations of the polar groups which are generated as a result of photooxidation such as carbonyl groups can be monitored as characteristic relaxation processes like the αc or β mode. The dielectric loss characterized by typical dielectric parameters like the activation energy and dielectric strength are strongly dependent upon changes induced by photooxidation in the amorphous and crystalline domains. This paper discusses in detail how the foil reached its mechanical disintegration. It was found that initial stages of weathering induce chain scission and/or crosslinking in the amorphous domains of the polymer and the motional processes in the crystalline regions are not affected. After this induction period, an increase in the degree of crystallization was observed by employing differential calorimetry. The increasing crystallinity is considered as one of the reasons for embrittlement which finally leads to the complete loss of the structural integrity. KW - Artificial weathering KW - UV radiation KW - Dielectric relaxation KW - LDPE PY - 2012 DO - https://doi.org/10.1016/j.tca.2011.12.003 SN - 0040-6031 SN - 1872-762X VL - 530 SP - 73 EP - 78 PB - Elsevier CY - Amsterdam AN - OPUS4-25547 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Daus, Lars-Hendrik A1 - Schartel, Bernhard A1 - Wachtendorf, Volker A1 - Mangelsdorf, R. A1 - Korzen, Manfred T1 - A chain is no stronger than its weakest link: Weathering resistance of water-based intumescent coatings for steel applications N2 - A systematic approach was used to investigate the weathering-induced degradation of a common water–based intumescent coating. In this study, the coatings are intended for humid indoor applications on steel substrates. The coating contains ammonium polyphosphate, pentaerythritol, melamine, and polyvinyl acetate. By replacing each ingredient with a less water-soluble substance, the most vulnerable substances, polyvinyl acetate and pentaerythritol, were identified. Furthermore, the weathering resistance of the system was improved by exchanging the ingredients. The coatings were stressed by artificial weathering tests and evaluated by fire tests. Thermogravimetry and Fourier-transform infrared spectroscopy were used to study the thermal decomposition. This study lays the foundation for the development of a new generation of water-based intumescent coatings. KW - Intumescence KW - Fire resistance KW - Fire protective coatings KW - Weathering KW - Thermogravimetric analyses PY - 2021 DO - https://doi.org/10.1177/0734904120961064 SN - 0734-9041 SN - 1530-8049 VL - 39 IS - 1 SP - 72 EP - 102 PB - SAGE AN - OPUS4-52015 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -