TY - CONF A1 - Erdmann, Maren A1 - Braun, Ulrike A1 - Dümichen, Erik A1 - Trappe, Volker T1 - Epoxy cure kinetics by in situ NIR-measurements N2 - The application of epoxy resins is variating from low cost adhesive to high performance plastics. As a result, the choice of monomer, hardener and in particular the curing treatment define the final product properties. For process optimization and ensuring product quality the curing kinetics of epoxy resin needs to be known. This is usually done by use of differential scanning calorimetry (DSC) or rheology measurements. In the presented study, we will approve the applicability of the heatable near-infrared (NIR) cell 1 as alternative method to determine cure kinetics. This spectroscopic method in the NIR region enables following the cure progress by the characteristic oxirane absorption band 2,3. According to the reactivity of this functional group, the consumption of it should be a key factor for cross linking density and hence the mechanical performance of the material. Kinetic parameters will be provided by non-isothermal heating rates and predicted epoxy conversion for a typical cure treatment (Figure 1). The verification of the investigated cure kinetics is ensured by multiple step curing processes in the in situ NIR heating cell and ex situ on real samples. In this presentation, we will introduce the heatable near-infrared (NIR) cell to investigate kinetic parameters for various epoxy resins, using diverse curing processes. Advantages and disadvantages of the method will be described as well as the comparison with DSC results. T2 - MoDeSt 2016 CY - Cracow, Poland DA - 04.09.2016 KW - epoxy resin KW - curing kinetics KW - in situ near-infrared (NIR) spectroscopy KW - differential scanning calorimetry (DSC) PY - 2016 AN - OPUS4-37321 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Erdmann, Maren A1 - Niebergall, Ute A1 - Toepel, Jörg A1 - Böhning, Martin T1 - Diesel and biodiesel induced degradation of polyethylene N2 - Renewable resources become more and more relevant to maintain energy demands for an increasing global population. Biosynthetic fuels like biodiesel might replace conventional petrochemical fuels, such as diesel. However, more research is needed to characterize the interaction between the different fuels and the polymeric material, especially with respect to ageing and degradation. The poster will present several interaction and degradation phenomena of high density polyethylene (PE-HD) induced by diesel and biodiesel 1-3. Also the possible influence of microbial growth (fungi and bacteria) is considered. The chosen PE-HDs are typical thermoplastic resins for container and storage tank applications. Degradation of PE-HD will be investigated by changes of the mechanical properties – with main emphasis on the Charpy impact strength 2. Furthermore, with alternating sorption and desorption cycles in combination with oven ageing the co-oxidation 3 of PE-HD in contact with biodiesel will be addressed. T2 - MoDeSt 2016 CY - Cracow, Poland DA - 04.09.2016 KW - Impact strength KW - PE-HD KW - Diesel KW - Biodiesel KW - Degradation PY - 2016 AN - OPUS4-37320 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Erdmann, Maren A1 - Niebergall, Ute A1 - Böhning, Martin T1 - Mechanical characterization of high-density polyethylene in contact with diesel and biodiesel fuels N2 - Renewable resources become more and more relevant to maintain energy demands for an increasing global population. Biosynthetic fuels like biodiesel might replace conventional petrochemical fuels, such as diesel. However, more research is needed to characterize the interaction between the different fuels and polymeric materials widely used in the fuel infrastructure as well as for automotive parts. Especially changes in the structural properties and mechanical behavior of the polyethylene (PE-HD) have to be addressed. The presented work comprises the direct interaction of high density polyethylene (PE-HD) with diesel and biodiesel, resulting in swelling and plasticization. Also long-term degradation phenomena will be discussed. The chosen PE-HD types are typical thermoplastic resins for container and storage tank applications. The impact of diesel and biodiesel in PE-HD is investigated by changes in the mechanical properties with emphasis on the Charpy impact strength. Furthermore, structural and dynamic influences on the polymeric material induced by diesel and biodiesel are proven in Dynamic Mechanical Analysis (DMA). Both methods, Charpy impact strength and DMA, reveal softening effects due to the migration of diesel and biodiesel into the amorphous regions of PE-HD. Since biodiesel is more prone to oxidative degradation compared to diesel, the fuel/air/polymer-interaction is studied for partly immersed tensile test specimens. Main focus of the evaluation is the co-oxidation. Here, the accelerated deterioration of PE caused by the sorption of the facile oxidation of biodiesel into the solid polymer might be a major degradation mechanism in this context. T2 - POLYDAYS 2016 CY - Potsdam, Germany DA - 28.09.2016 KW - PE-HD KW - Diesel KW - Biodiesel KW - Oxidation PY - 2016 AN - OPUS4-37677 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dümichen, Erik A1 - Javdanitehran, M. A1 - Erdmann, Maren A1 - Trappe, Volker A1 - Sturm, Heinz A1 - Braun, Ulrike A1 - Ziegmann, G. T1 - Analyzing the network formation and curing kinetics of epoxy resins by in situ near-infrared measurements with variable heating rates N2 - Near-infrared spectroscopy (NIR) turned out to be well suited for analyzing the degree of cure for epoxy systems. In contrast to dynamic scanning calorimetry (DSC), where the released heat of reaction determines the degree of epoxy conversion indirectly, NIR spectroscopy is able to determine the conversion directly by analyzing structural changes. Therefore, a new heatable NIR cell was equipped with an integrated thermocouple, which enables the real sample temperature to be controlled and monitored in situ during epoxy curing. Dynamic scans at different heating rates were used for kinetic modelling, to define kinetic parameters and to predict real curing processes. The kinetic models and their parameters were validated with an isothermal and a more complex multi-step curing scenario. Two available commercial epoxy systems based on DGEBA were used with an anhydride and with an amine hardener. NIR results were compared with DSC data. The simulated conversion predicted with a model fitted on the basis of NIR and DSC dynamic scans showed good agreement with the conversion measured in the isothermal curing validation test. Due to the proven reliability of NIR in measuring the reaction progress of curing, it can be considered a versatile measurement system for in situ monitoring of component production in the automotive, aerospace and wind energy sectors. KW - Epoxy resins KW - Curing kinetics KW - Near-infrared spectroscopy KW - DSC PY - 2015 U6 - https://doi.org/10.1016/j.tca.2015.08.008 SN - 0040-6031 SN - 1872-762X VL - 616 SP - 49 EP - 60 PB - Elsevier CY - Amsterdam AN - OPUS4-34187 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Erdmann, Maren A1 - Trappe, Volker A1 - Sturm, Heinz A1 - Braun, Ulrike A1 - Dümichen, Erik T1 - Cure conversion of structural epoxies by cure state analysis and in situ cure kinetics using nondestructive NIR spectroscopy N2 - Non-isothermal heating rate kinetics was applied to two epoxy resin systems. In situ near-infrared (NIR) measurements were taken with a heatable NIR cell which allowed the cure to be monitored by characteristic absorption bands. An autocatalyzed reaction of the nth order was shown to describe the epoxy conversion curves. Differential Scanning Calorimetry (DSC) was used as a complementary method. The kinetic models developed by both NIR and DSC are in good accordance with experimental epoxy conversion in the in situ NIR setup for single and multiple cure temperature ramps. A linear calibration curve of the characteristic absorption bands of epoxy normalized to aromatic vibrations was introduced. The curing degree of structural epoxies that were cured according to an industrial temperature cure profile was determined by NIR using the calibration curve. The epoxy conversions of the structural components showed good agreement with the experimental in situ NIR. Several degrees of cure for structural specimens were evaluated by NIR and residual reaction enthalpy by DSC. We present the non-destructive NIR spectroscopy as an alternative to determine fast and non-destructive epoxy conversion, particularly suitable for high degrees of cure on structural components. KW - Epoxy resin KW - Curing kinetics KW - In situ near-infrared (NIR) spectroscopy KW - Differential scanning calorimetry (DSC) PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S0040603117300205 U6 - https://doi.org/10.1016/j.tca.2017.01.010 SN - 0040-6031 SN - 1872-762X VL - 650 SP - 8 EP - 17 PB - Elsevier B.V. AN - OPUS4-39123 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Erdmann, Maren A1 - Kupsch, Andreas A1 - Müller, Bernd R. A1 - Hentschel, Manfred P. A1 - Niebergall, Ute A1 - Böhning, Martin A1 - Bruno, Giovanni ED - Erdmann, Maren T1 - Diesel-induced transparency of plastically deformed high-density polyethylene N2 - High-density polyethylene becomes optically transparent during tensile drawing when previously saturated with diesel fuel. This unusual phenomenon is investigated as it might allow conclusions with respect to the material behavior. Microscopy, differential scanning calorimetry, density measurements are applied together with two scanning X-ray scattering techniques: wide angle X-ray scattering (WAXS) and X-ray refraction, able to extract the spatially resolved crystal orientation and internal surface, respectively. The sorbed diesel softens the material and significantly alters the yielding characteristics. Although the crystallinity among stretched regions is similar, a virgin reference sample exhibits strain whitening during stretching, while the diesel-saturated sample becomes transparent. The WAXS results reveal a pronounced fiber texture in the tensile direction in the stretched region and an isotropic orientation in the unstretched region. This texture implies the formation of fibrils in the stretched region, while spherulites remain intact in the unstretched parts of the specimens. X-ray refraction reveals a preferred orientation of internal surfaces along the tensile direction in the stretched region of virgin samples, while the sample stretched in the diesel-saturated state shows no internal surfaces at all. Besides from stretching saturated samples, optical transparency is also obtained from sorbing samples in diesel after stretching. KW - PE-HD Sorption KW - Cavitation KW - Diesel Fuel KW - X-ray refraction KW - WAXS KW - Internal Surfaces KW - Crystal Texture PY - 2019 U6 - https://doi.org/10.1007/s10853-019-03700-8 SN - 1573-4803 SN - 0022-2461 VL - 54 IS - 17 SP - 11739 EP - 11755 PB - Springer US CY - US AN - OPUS4-48226 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Erdmann, Maren A1 - Kleinbub, Sherin A1 - Wachtendorf, Volker A1 - Schütter, Jan David A1 - Niebergall, Ute A1 - Böhning, Martin A1 - Koerdt, Andrea T1 - Photo-oxidation of PE-HD affecting polymer/fuel interaction and bacterial attachment N2 - In the present study, a simple approach was used to investigate the effect of UV-exposure on two high density Polyethylene materials (PE-HD), commonly used for storage tanks, on fuel sorption behavior and colonization by microorganisms. The aim was to investigate whether the sorption behavior of the fuels (diesel/biodiesel) and the colonization by microorganisms, frequently occurring in the fuel, is affected and may lead to undesirable or safety-relevant material changes. We showed that the UV-irradiation leads to significant changes of the sorption behavior due to chemi-crystallization and crosslinking. The fuel Sorption is affected by the UV-induced formation of polar carbonyl and hydroxyl groups predominantly occurring at the surface. With respect to microbial colonization behavior for Bacillus subtilis and Pseudomonas aeruginosa, isolated from a contaminated diesel sample, differences of the initial adhesion could be shown depending on the initial type of polyethylene as well as on the degree of UV-induced degradation. KW - High density polyethylene KW - Bacterial attachment KW - UV-irradiation KW - Fuel sorption PY - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-510001 VL - 4 IS - 1 SP - Article number: 18 PB - Nature Partner Journals AN - OPUS4-51000 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Erdmann, Maren A1 - Niebergall, Ute A1 - Wachtendorf, Volker A1 - Böhning, Martin T1 - Evaluation of UV-induced embrittlement of PE-HD by Charpy impact test N2 - The impact fracture behavior of two common high-density polyethylene grades for container applications were intensively studied by the instrumented Charpy impact test after well-defined exposure to UV-irradiation. Individual stages of the impact event, such as crack initiation and crack propagation energy as well as maximum impact load, were investigated from the recorded load–deflection curves. UV-induced material property changes were further investigated by infrared spectroscopy, differential scanning calorimetry, and dynamic-mechanical analysis as well as density measurements. Based on the results of the Charpy impact test, three indicators were identified to describe the extend of photooxidation on high-density polyethylene: (a) a reduced Charpy impact strength—at least to half of its initial value for a distinctly brittle impact fracture, (b) a marked decrease in the crack propagation contribution to the impact strength, and (c) an increase of the brittle features of the fracture surface. KW - Degradation KW - Mechanical properties KW - Packaging KW - Polyolefins KW - Polyethylene PY - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-509130 SN - 0021-8995 VL - 137 IS - 36 SP - 49069 PB - Wiley AN - OPUS4-50913 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Erdmann, Maren A1 - Niebergall, Ute A1 - Böhning, Martin A1 - Sameith, Janin T1 - Effect of surface degradation on high-density polyethylene for biofilm formation N2 - Renewable resources become more and more relevant to maintain energy demands for an increasing global population. Biosynthetic fuels like biodiesel might replace conventional petrochemical fuels. In this study the influence of microbial growth on biodiesel and diesel on the storage tank systems were investigated. Polymeric fuel storage tanks for diesel and biodiesel provide suitable environmental conditions for a broad spectrum of fungi and various bacteria, including cyanobacteria and aerobic heterotrophic, and even anaerobic, fermentative Bacteria. However, the questions whether and how ageing of the materials is affected by biofouling processes have not been answered so far. Therefore, a model system for biofilm formation was established to study the initial attachment phase of bacteria in dependency of ageing, quality and surface modification of thermoplastic polymers used for storage tank systems. The microbial survey is closely connected with a detailed characterization of the material’s properties and its ageing processes. A widely applied plastic used for fuel storage tanks is high-density polyethylene (PE-HD), which is available with various additives to increase UV-light stability and even for the storage of biodiesel. These materials were aged under UV-light and temperature using a defined climate chamber set-up. Further, the repeated filling of fuels was mimicked for such storage tanks, as this has an important impact on the life-cycle length for the storage Container. The aged polymers showed a significant change in the material’s characteristics, including surface characteristics (e.g. hydrophobicity) and carbonyl groups. The effect of the changed material properties on the biofilm formation are studied using bacterial isolates, previously obtained from a “dieselpest”, and as a model-reference E. coli. The unaged polymers showed already some significant differences for the initial attachment of E. coli K12. Polyethylene with additives was colonized faster than the reference material (without additives) although the final biofilm coverage was not impaired. Likewise, the settlement of a kerosene-isolated Bacillus species on the unaged materials independently of additives was only minor interfered. In future, our results should give stakeholders in industry and public authorities a better estimation of the life-cycle security for fuel storage tank systems and on the fuel quality. Further, our results could help to test and develop new materials or additives to prevent biofouling processes. T2 - VAAM Jahrestagung CY - Würzburg, Germany DA - 05.03.2017 KW - PE-HD KW - Biofilm KW - MIC KW - Degradation PY - 2017 AN - OPUS4-39457 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Erdmann, Maren A1 - Böhning, Martin A1 - Niebergall, Ute T1 - Physical and chemical effects of biodiesel storage on high-density polyethylene: Evidence of co-oxidation N2 - The physical and chemical effects of diesel and biodiesel fuels on two high-density polyethylene (PE-HD) types were investigated. Both semi-crystalline PE-HD are common thermoplastic materials for container and storage tank applications. Biodiesel, a composition of unsaturated fatty acid esters from renewable resources, was chosen as it is regarded a possible green alternative to fossil fuels. The study aims at identifying significant differences between biodiesel and conventional diesel fuels based on the differences in the chemical nature of the two. The physical effects of the fuels on the polymer at first comprises the sorption behavior, i.e. kinetics and final equilibrium concentration. Not only are both fuels absorbed by the amorphous phase of the semi-crystalline PE-HD, they also induce a plasticization effect that modifies the molecular mobility and therefore also the characteristic yielding properties, manifest in the obtained stress-strain curves. The chemical effects related to degradation phenomena is investigated by a long-term storage scenario using partially immersed tensile test specimens in diesel and biodiesel. We were able to confirm the proposed co-oxidation mechanism by Richaud et al. for polyethylene-unsaturated penetrant systems on a larger scale based on practical tensile tests. One of the investigated polyethylene grades subjected to tensile drawing showed a significant loss of plastic deformation and the onset of premature failure after 150 days of storage in biodiesel. Further biodiesel storage showed a systematically reduced elongation at break before necking. None of these effects were observed in diesel. Oxidation of fuels and polymer after progressing storage times were analyzed by the evolution of carbonyl species in FT-IR/ATR spectroscopy. KW - Biodiesel KW - Degradation KW - Long-term storage KW - Sorption KW - Diesel PY - 2019 U6 - https://doi.org/10.1016/j.polymdegradstab.2019.01.018 SN - 0141-3910 VL - 161 IS - 1 SP - 139 EP - 149 PB - Elsevier CY - Amsterdam AN - OPUS4-47268 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Erdmann, Maren A1 - Kleinbub, Sherin A1 - Böhning, Martin A1 - Niebergall, Ute A1 - Koerdt, Andrea T1 - Initial attachment of bacteria on PE-HD by fluorescence microscopy and colony-forming unit N2 - The first documentation of fuel biodeterioration dates back to the late 19th century. However, extensive studies concerning the microbial fuel contamination started in 1980’s. Polymeric fuel storage tanks containing diesel and biodiesel provide environmental conditions for microbial growth. Several studies demonstrated that bacteria, which were found in contaminated fuel systems, can use fuels as macronutrient; but such bacteria can also cause microbiologically influenced corrosion and fouling. The aim of this study is to investigate the initial attachment behavior of bacteria, isolated from a diesel contamination, on neat and photooxidized high-density polyethylene (PE-HD). Two common PE-HD’s, less- and biodiesel-stabilized, were radiated to UV light representing a tank exposed to sunlight. The effect of photooxidiation on PE-HD’s surface were characterized chemically by Fourier-transform infrared spectroscopy (FTIR). The attached bacteria Pseudomonas aeruginosa and Bacillus subtilis on the polymer surface were evaluated by fluorescence microscopy and colony-forming unit tests (CFU). T2 - MoDeSt2018 CY - Tokio, Japan DA - 02.09.2018 KW - PE-HD KW - Initial attachment KW - UV-irradiation PY - 2018 AN - OPUS4-45893 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Erdmann, Maren A1 - Wachtendorf, Volker A1 - Böhning, Martin A1 - Niebergall, Ute T1 - PE-HD as a polymeric fuel storage tank material: Photooxidation, fuel sorption and long-term storage N2 - High-density polyethylene (PE-HD) is a commodity thermoplastic polymer which is typically used for packing of dangerous goods. Its good resistance against photooxidation, fuels, chemicals and other environmental factors in addition to low production costs makes PE-HD attractive for fuel storage applications. Typical engine fuels stored in polymer tanks are petrol, diesel and biodiesel that receives increasing attention as proper alternative to fossil fuels. One of the major problems with biodiesel is its susceptibility to oxidize due to its chemical composition of unsaturated fatty acids which also can cause polymer degradation. The aim of this study is to investigate the influence of different environmental factors, UV radiation and commonly stored fuels, on the mechanical, physical and chemical properties of two types of PE-HD polymers (stabilized and non-stabilized). The influence on the mechanical properties was tested by Charpy and tensile tests, chemical and physical properties were evaluated by Fourier-transform infrared spectroscopy (FTIR) and by dynamical mechanical analysis (DMA) tests. Samples were characterized after varying exposure time of UV radiation and after fully and partially immersion in biodiesel. In addition, similar experiments were conducted using diesel for comparison. T2 - MoDeSt2018 CY - Tokio, Japan DA - 02.09.2018 KW - PE-HD KW - Biodiesel KW - UV-irradiation KW - Long-term storage KW - Diesel PY - 2018 AN - OPUS4-45894 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Erdmann, Maren A1 - Wachtendorf, Volker A1 - Sameith, Janin A1 - Niebergall, Ute A1 - Böhning, Martin T1 - Effect of surface degradation on high-density polyethylene for initial attachment of bacillus and pseudomonas N2 - High-density polyethylene (PE-HD) is a widely applied plastic for fuel storage tank applications. But such tanks, filled with diesel or biodiesel, provide excellent environmental conditions for growth of a broad spectrum of fungi and various bacteria1. This can result in fuel contamination, engine plugging or possible (bio-) degradation2. Our research focusses on the initial attachment phase of Bacillus sp. and Pseudomonas aeruginosa isolated from a „dieselpest“2 on two distinctly PE-HD materials, typical for fuel storage tank applications, pre-damaged thermally and by UV-irradiation. T2 - PDDG CY - Taormina, Sicily, Italy DA - 04.09.2017 KW - PE-HD KW - UV-irradiation KW - Initial attachment KW - Bacteria PY - 2017 AN - OPUS4-41908 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Erdmann, Maren A1 - Niebergall, Ute A1 - Böhning, Martin T1 - Long-term storage of high-density polyethylene in biodiesel and diesel fuels N2 - Sustainable energy and clean engine fuels receive more and more attention. Petrodiesel could be substituted by biofuels such as biodiesel produced from renewable resources. Biodiesel is derived by transesterification of oils with alcohols for example vegetable oils, animal fats or food waste. Its chemical composition of unsaturated fatty methyl acids causes biodiesels susceptibility to oxidation. Especially, the polymer-biodiesel performance under long-term conditions has been considered only in few researches. Our study addresses a long-term storage scenario of a polymeric fuel tank containing biodiesel or diesel. T2 - PDDG CY - Taormina, Sicily, Italy DA - 04.09.2017 KW - PE-HD KW - Degradation KW - Biodiesel KW - Diesel PY - 2017 AN - OPUS4-41909 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -