TY - JOUR A1 - Böhning, Martin A1 - Niebergall, Ute A1 - Adam, Adeline A1 - Stark, Wolfgang T1 - Impact of biodiesel sorption on mechanical properties of polyethylene N2 - The time-dependent sorption of biodiesel in a typical polyethylene for container applications is investigated in comparison to conventional diesel fuel at three different temperatures. In this context, the desorption behavior is also addressed. Subsequently, the effects of both penetrants on mechanical properties are characterized in terms of impact strength and dynamic-mechanical analysis. The discussion of property changes is firstly based on the sorption kinetics of biodiesel and diesel, which is determined by immersion experiments allowing for the calculation of respective diffusion coefficients. Changes in impact strength as determined by the Charpy method are further characterised in more detail by analyzing the fracture surfaces, and correlated with results of dynamic-mechanical analysis. KW - Biodiesel KW - Fuel sorption KW - Desorption KW - Impact strength KW - Dynamic-mechanical analysis KW - PE-HD PY - 2014 DO - https://doi.org/10.1016/j.polymertesting.2013.12.003 SN - 0142-9418 VL - 34 SP - 17 EP - 24 PB - Elsevier Science CY - Amsterdam [u.a.] AN - OPUS4-30096 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Linhares, F.N. A1 - Kersch, M. A1 - Niebergall, Ute A1 - Leite, M.Ch.A.M. A1 - Altstädt, V. A1 - Furtado, C.R.G. T1 - Effect of different sulphur-based crosslink networks on the nitrile rubber resistance to biodiesel N2 - Biodiesel possesses some comparable physical properties to petroleum diesel in addition to its improved environmental benefits. Nonetheless, both fuels differ greatly with respect to their chemical compositions. Therefore, the compatibility of the materials, which are commonly employed in contact with diesel, must also be assured for biodiesel. This paper assessed the influence of sulphur-based curing systems on the resistance of nitrile rubber to soybean biodiesel. Formulations were prepared using highacrylonitrile-content nitrile rubber by employing a two-level experimental design. The amounts of two different accelerators and sulphur were varied to achieve different types of vulcanisation systems. Thermal analyses, mechanical tests and microscopy analyses were conducted to evaluate the behaviour of the material after contact with biodiesel. The results showed that the choice of the accelerator played an important role on the resistance of the rubber to the biofuel, and crosslink density was not a key factor with respect to the resistance. KW - Soyean oil KW - Nitrile rubber KW - Compatibility KW - Vulcanisation system KW - Biodiesel KW - Resistance PY - 2017 DO - https://doi.org/10.1016/j.fuel.2016.11.060 SN - 0016-2361 SN - 1873-7153 VL - 191 SP - 130 EP - 139 AN - OPUS4-39006 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 - Böhning, Martin A1 - Niebergall, Ute A1 - Adam, Adeline A1 - Stark, Wolfgang T1 - Influence of biodiesel sorption on temperature-dependent impact properties of polyethylene N2 - In a previous paper we investigated the influence of sorbed biodiesel or diesel on mechanical properties of a typical polyethylene grade for tank applications. Besides the basic sorption and desorption behavior of these two fuels, the study addressed the concentration-dependent mechanical properties as revealed by a non-instrumented Charpy impact test and dynamic mechanical analysis (DMA). In the present paper we extend this investigation focusing on the temperature-dependent impact fracture behavior. Therefore, an instrumented Charpy impact test was employed, allowing a more detailed analysis of the fracture behavior. Furthermore, from the load-time-diagrams obtained from the instrumented impact test, corresponding fracture times can be calculated, allowing a clear correlation of the fuel sorption induced changes in fracture toughness with the enhanced ß-relaxation observed by DMA. As in the previous study, the fracture surfaces of the impact tested specimens were analyzed in order to confirm the brittle or ductile character of the fracture indicated by impact strength and the corresponding load-deflection diagrams. KW - Biodiesel KW - Fuel sorption KW - Impact strength KW - Charpy impact test KW - Dynamic-mechanical analysis KW - Relaxation KW - PE-HD PY - 2014 DO - https://doi.org/10.1016/j.polymertesting.2014.09.001 SN - 0142-9418 VL - 40 SP - 133 EP - 142 PB - Elsevier Science CY - Amsterdam [u.a.] AN - OPUS4-31583 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schilling, Markus A1 - Böhning, Martin A1 - Oehler, H. A1 - Alig, I. A1 - Niebergall, Ute T1 - Environmental stress cracking of polyethylene high density (PE-HD) induced by liquid media – Validation and verification of the full-notch creep test (FNCT) T1 - Umgebungsinduzierte Spannungsrissbildung von Polyethylen- Werkstoffen hoher Dichte durch flüssige Medien – Validierung und Verifizierung des Kriechversuchs an Probekörpern mit umlaufender Kerbe N2 - The full-notch creep test (FNCT) is widely used to characterize the slow crack growth (SCG) behavior of polyolefin materials in “inert” media as well as effects of environmental stress cracking (ESC) in which the medium has decisive influence on damage mechanism and time to failure. The test is of greatest importance for pipe and blow molding types of polyethylene, high density (PE-HD). Usually the full-notch creep test is applied as a standardized testing method (ISO 16770) using a few universal liquid media, such as solutions of Arkopal N 100. In our study, selected relevant polyethylene, high density materials are investigated also in real media – practical formulations as well as representative pure chemicals – and influences of temperature and geometry of specimen and notch are explicitly addressed. Furthermore, the investigations comprise also the environmental stress cracking behavior of polyethylene, high density in media that are sorbed to a significant extent – examples are diesel and biodiesel – based on comparison with samples previously saturated with those media. Thus, also the underlying diffusion controlled sorption process has to be assessed before. The investigations were performed using a full-notch creep testing device with 12 individual sub-stations, each equipped with individual electronic stress and temperature control and continuous online monitoring of the specimen elongation. N2 - Der Kriechversuch an Probekörpern mit umlaufender Kerbe (FNCT) wird flächendeckend angewendet, um das Verhalten von Polyolefinen sowohl gegenüber langsamen Risswachstums (SCG) bei Kontakt mit „inerten“ Medien als auch gegenüber umgebungsbedingtem Spannungsrisswachstum (ESC), bei welchem das umgebende Medium entscheidenden Einfluss auf den Schädigungsmechanismus und die Standzeit hat, zu charakterisieren. Der Test ist von großer Bedeutung bei der Analyse von hochdichten Polyethylen-Typen, die als Rohr- und Blasformwerkstoffe angewendet werden – dabei besonders für Transport und Verpackung von Gefahrstoffen, aber auch für weitere Hochleistungsanwendungen. Üblicherweise wird der Kriechversuch an Probekörpern mit umlaufender Kerbe als Normmethode (ISO 16770) unter Verwendung einiger weniger universeller Modellflüssigkeiten, wie z. B. Arkopal N 100, durchgeführt. In dieser Studie werden ausgewählte, marktrelevante Polyethylen-Werkstoffe hoher Dichte in realen Medien – praktisch verwendete Gefahrgüter sowie repräsentative reine Chemikalien – untersucht und explizit die Einflüsse von Temperatur und Prüfkörper- sowie Kerbgeometrie adressiert. Weiterhin beinhalten die Untersuchungen die Analyse des umgebungsbedingten Spannungsriss-Verhaltens von Polyethylen hoher Dichte in Medien, die maßgeblich vom Werkstoff sorbiert sind – beispielsweise mit Kraftstoffen wie diesel und biodiesel – basierend auf dem Vergleich mit vorgesättigten Probekörpern. Der dabei vorliegende diffusionsgesteuerte Sorptionsprozess muss dementsprechend zuvor evaluiert werden. Alle Untersuchungen wurden mithilfe einer Kriechversuchsanlage an Probekörpern mit umlaufender Kerbe mit 12 Stationen durchgeführt, welche jeweils mit einer individuell ansteuerbaren elektronischen Spannungs- und Temperatursteuerung sowie fortwährender Online-Überwachung der Prüfkörperdehnung ausgestattet sind. KW - Full-notch creep test (FNCT) KW - Polyethylene (PE-HD) KW - Environmental stress cracking (ESC) KW - Slow crack growth (SCG) KW - Biodiesel PY - 2017 DO - https://doi.org/10.1002/mawe.201700065 SN - 1521-4052 SN - 0933-5137 VL - 48 IS - 9 SP - 846 EP - 854 PB - Wiley-VCH CY - Weinheim AN - OPUS4-41885 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 DO - 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 - JOUR A1 - Schilling, Markus A1 - Marschall, Niklas A1 - Niebergall, Ute A1 - Wachtendorf, Volker A1 - Böhning, Martin T1 - Unveiling Effects of Biodiesel and Diesel on Environmental Stress Cracking of PE-HD N2 - The behavior of high‐density polyethylene with respect to resistance against environmental stress cracking (ESC) is usually regarded as an inherent material property being specific for respective types of PE‐HD and tested using standardized methods, conditions, and also standard testing liquids (usually aqueous surfactant solutions). On the other hand, for practical applications the ESC behavior of those polymeric materials, commonly used for pipes or containers, in contact with other liquids (e.g., fuels) is often of relevant interest, but for a reasonable assessment, where consistent benchmark data for a direct comparison are often missing, it is essential to determine the actually prevailing failure mode and classify it related to crack propagation or other mechanisms. Using the well‐established Full Notch Creep Test, which favorably allows for a detailed microscopic fracture surface analysis after failure, the behavior of two typical PE‐HD types for container applications is investigated in biodiesel and diesel and compared to a standard surfactant solution. This enables a clear identification of characteristic features of the interaction of biodiesel and diesel as sorptive fuels in contact with the polymer, revealing the complex interplay of sorption and plasticization as well as ESC inducing effects on PE‐HD, which could be clearly shown for both fuels. KW - Biodiesel KW - Confocal laser scanning microscopy (LSM) KW - Diesel KW - Full notch creep test (FNCT) KW - Plasticization PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-650525 DO - https://doi.org/10.1002/pen.70239 SN - 0032-3888 SP - 1 EP - 16 PB - Wiley CY - Hoboken (NJ) AN - OPUS4-65052 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -