Improvement of the thermo-oxidative stability of biobased poly(butylene succinate) (PBS) using biogenic wine by-products as sustainable functional fillers. - In: Polymers, ISSN 2073-4360, Bd. 15 (2023), 11, 2533, S. 1-23
Biobased poly(butylene succinate) (PBS) represents one promising sustainable alternative to petroleum-based polymers. Its sensitivity to thermo-oxidative degradation is one reason for its limited application. In this research, two different varieties of wine grape pomaces (WPs) were investigated as fully biobased stabilizers. WPs were prepared via simultaneous drying and grinding to be used as bio-additives or functional fillers at higher filling rates. The by-products were characterized in terms of composition and relative moisture, in addition to particle size distribution analysis, TGA, and assays to determine the total phenolic content and the antioxidant activity. Biobased PBS was processed with a twin-screw compounder with WP contents up to 20 wt.-%. The thermal and mechanical properties of the compounds were investigated with DSC, TGA, and tensile tests using injection-molded specimens. The thermo-oxidative stability was determined using dynamic OIT and oxidative TGA measurements. While the characteristic thermal properties of the materials remained almost unchanged, the mechanical properties were altered within expected ranges. The analysis of the thermo-oxidative stability revealed WP as an efficient stabilizer for biobased PBS. This research shows that WP, as a low-cost and biobased stabilizer, improves the thermo-oxidative stability of biobased PBS while maintaining its key properties for processing and technical applications.
https://doi.org/10.3390/polym15112533
Comparison of the properties of biogenic wine by-products stabilized biocomposites compounded with a miniaturized single-screw extruder and a co-rotating twin-screw extruder. - In: Engineering for a changing world, (2023), 2.3.010, S. 1-13
Bioplastics research is hindered by high material prices and limited availability of biopolymers. For conventional compounding, even on lab-scale, large quantities of material are required. In this study, an alternative process for compounding biocomposites was evaluated to investigate the potential of wine-derived biogenic by-products as functional fillers. Formulations based on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and wine grape pomace (WP) with filler contents up to 10 wt.-% were prepared. The materials were processed with a modified miniaturized single-screw extruder (MSE) and compared to a lab-scale twin-screw extruder (TSE). Thermal and rheological properties of the materials were determined using GPC, MFR, DSC, TGA and OIT. The mixing quality of both extruders was evaluated by optical microscopy imaging. The results revealed that the MSE represents an efficient alternative for research purposes, but differences in the dominant degradation mechanisms during processing must be considered. Thermal analysis showed that WP successfully suppressed the thermo-oxidative degradation of PHBV.
https://doi.org/10.22032/dbt.58862
Influence of the recycling process parameters on CFRTP waste properties. - In: Engineering for a changing world, (2023), 2.3.002, S. 1-12
Nowadays, the combination of continuous fibers and thermoplastic polymers as the matrix to continuous fiber-reinforced thermoplastics (CFRTP) is receiving increasing attention due to their potential advantages such as excellent weight-specific mechanical properties, short cycle times, storability, repeated meltability, good formability and the use of alternative joining processes enabling automated large volume manufacturing processes which allow various applications in different industries including transportation, construction among others. As the production rate of these materials increases, the amount of waste for disposal increases, for which recycling strategies need to be established to ensure the sustainability of CFRTP. Hence, these recycling strategies must be developed and evaluated economically and ecologically to close the loop and achieve a circular economy to process recycled fiber-reinforced pellets from CFRTP waste to valuable products e.g., by injection molding. This study presents a mechanical recycling approach from CFRTP waste to injection molded test specimens and evaluates the impact of the individual recycling steps along the recycling chain on the fiber length as the fiber length is detrimental to the resulting mechanical properties. First, the CFRTP waste processability is investigated and conditions for size reduction by cutting and shredding into feedstock for extrusion are defined. Second, fiber-reinforced pellets are produced by twin-screw extrusion. The fiber volume content and the process parameters screw speed and temperature during compounding are varied and the influence of these parameters on the fiber length is determined. Third, the extruded pellets are further processed by injection molding. Here, the influence of screw speed, back pressure, and processing temperature as well as the initial fiber length in the extruded granules on the resulting properties is investigated. Quantitative correlations between material properties and processing parameters are presented and suggestions for gentle processing during recycling are given.
https://doi.org/10.22032/dbt.58866
Influence of the processing on the properties of continuous fiber reinforced thermoplastic sheets prepared by extrusion. - In: AIP conference proceedings, ISSN 1551-7616, Bd. 2884 (2023), 1, 050005, S. 050005-1-050005-14
Continuous fiber reinforced thermoplastics (CFRT) are composite materials consisting of continuous fibers and a thermoplastic matrix and offer outstanding mechanical properties, low densities, short cycle times and recyclability. CFRT can be classified into unidirectional tapes and sheets utilizing various semi-finished textiles as reinforcement. CFRT sheets are of interest for area measured products or multiaxial loads. Various discontinuous and semi-continuous methods to prepare CFRP sheets are described in the literature. All these methods either feature high cycle times or high investment costs and require double melting of the polymer, e.g., first to produce a polymer film and second to produce the CFRT sheet. An energy efficient alternative to produce CFRT sheets is extrusion, which allows to spare one melting step. A twin-screw extruder melts the polymer, which is then conveyed by a melt pump to the film extrusion dies and applied to both sides of the semi-finished textile, which is wetted and consolidated using a calendar. Due to the high melt viscosity and the line load at the calendar the major challenge is to achieve full void-free impregnation of the semi-finished textile. The mechanical properties of a CFRT sheet are determined by fiber and void volume content. Hence, the influence of the processing conditions on the fiber and void volume content as well as the mechanical properties were examined applying a parametric study of the die temperature, the haul-off speed, and the gap between the calendar rolls. The properties of the extruded CFRT sheets were compared to compression molded sheets. The fiber volume content was directly adjusted by the haul-off speed and the extruder throughput. An increasing die temperature lowers the melt viscosity and results in an increased fiber volume content. Scanning electron microscopy shows complete macro impregnation between the fiber bundles but not completely wetted individual filaments within fiber bundles.
https://doi.org/10.1063/5.0168183
Investigation of the fiber length and the mechanical properties of waste recycled from continuous glass fiber-reinforced polypropylene. - In: Recycling, ISSN 2313-4321, Bd. 8 (2023), 6, 82, S. 1-20
This paper explores the mechanical recycling of continuous fiber-reinforced thermoplastics (CFRTPs) waste into injection molded products, focusing on the influence of recycling parameters on fiber length and mechanical properties. CFRTPs are gaining attention for their promising attributes, including weight-specific mechanical properties, short cycle times, storability, and recyclability, making them suitable for diverse applications. However, as CFRTP production rates rise, recycling strategies become crucial for sustainability. This study investigates the processability of CFRTP waste, defines size reduction conditions, and evaluates the impact of various compounding parameters such as temperature, screw speed, and fiber volume content during extrusion. The research findings indicate that higher screw speeds lead to fiber length reduction, whereas elevated temperatures result in longer fibers. Increased fiber volume intensifies interactions, resulting in shorter lengths. Additionally, the study examines the influence of injection molding parameters such as back pressure, screw speed, and initial fiber length on the resulting fiber length and mechanical properties of injection molded specimens, emphasizing the need for precise parameter control to optimize performance in recycled CFRTPs. Key findings are that increasing the initial fiber length from 260 μm to 455 μm results in an average fiber length after injection molding of 225 μm and 341 μm, respectively. This implies that longer initial fibers are more prone to breakage. Regarding the mechanical properties, increasing back pressure from 20 bar to 60 bar results in a reduction in Young’s modulus of approximately 40 MPa. Higher screw speed also reduces modulus by approximately 70 MPa due to intensified fiber-screw interactions. However, back pressure and screw speed have neutral effects on the tensile strength and the elongation at break.
https://doi.org/10.3390/recycling8060082
Investigation on the influence of process parameters on the mechanical properties of extruded bio-based and biodegradable continuous fiber-reinforced thermoplastic sheets. - In: Polymers, ISSN 2073-4360, Bd. 15 (2023), 18, 3830, S. 1-14
The use of bio-based and biodegradable matrix materials in fiber-reinforced polymers (FRPs) is an approach to reduce the consumption of fossil resources and the amount of polymer waste. This study aims to assess the influence of the process parameters on the resulting mechanical properties of extruded bio-based and biodegradable continuous fiber-reinforced thermoplastics (CFRTPs) in the form of sheets. Therefore, the impregnation temperature during the production of PLA/flax fiber composites is varied between 220 ˚C and 280 ˚C, and the consolidation pressure, between 50 bar and 90 bar. A design of experiments approach is used. Fiber contents of 28.8% to 34.8% and void contents of 6.8% to 15.5% are determined for the composites by optical measurements. To assess the mechanical properties, tensile tests are performed. Using the evaluation software Minitab, a strong negative influence of the consolidation pressure on the tensile modulus and the tensile strength is observed. Increasing the pressure from 50 bar to 90 bar results in a reduction in the tensile modulus of 50.7% and a reduction in the tensile strength of 54.8%, respectively. It is assumed that this is due to fibers being damaged by the external force exerted onto the materials during the consolidation process in the calender. The influence of the impregnation temperature on the mechanical properties cannot be verified.
https://doi.org/10.3390/polym15183830
Extrusion as an energy-efficient manufacturing process for thermoplastic organosheets. - In: Sheet Metal 2023, (2023), 43, S. 345-352
Organosheets combine the advantages of reinforcement fibers and thermoplastic polymers. By pairing these two materials, composites with outstanding mechanical properties and low densities can be produced. These semi-finished products can be further processed into complex and functionalized components by thermoforming or injection molding. There are a number of different manufacturing processes for continuous fiber reinforced thermoplastics (CFRT), however, most of them require long production times and recurrent melting of the polymer resulting in high energy and manufacturing costs. This study presents a novel extrusion process, that enables a continuous production of reinforced thermoplastic sheets with only one melting step. Due to the high energy efficiency and wide range of processible materials, this process shows a high potential for an economical production of CFRT. To investigate the extrusion process in more detail, the influence of the processing and the flow behavior of the polymer on the impregnation quality and the mechanical properties of the composites were studied. The results showed increasing fiber volume contents with lower polymer viscosities. Furthermore, higher die temperatures and pressures resulted in higher fiber volume contents and thus in higher mechanical properties. The experiments also revealed that a complete impregnation can currently not be achieved without an additional small double belt press due to the line load of the calender, the high viscosity of the melt and the short impregnation time.
https://doi.org/10.21741/9781644902417-43
Aushärteüberwachung von Klebstoffen durch luftultraschallinduzierte und geführte Wellen. - Ilmenau, 2023. - 1 Band (verschiedene Seitenzählung)
Technische Universität Ilmenau, Dissertation 2023
Klebstoffsysteme finden zunehmend Anwendung in den verschiedensten Industriesegmenten und substituieren oder ergänzen oftmals konventionell angewandte Verbindungsverfahren wie das Schweißen und Nieten. Gleichzeitig bestehen zahlreiche, genormte Prüfverfahren, um die Aushärtung von Klebstoffen zu charakterisieren. Diese beschränken sich auf die Untersuchung von Probenkleinstmengen im Labor auf Basis von z. B. rheologischen und kalorimetrischen Verfahren. Die dabei erzielten Ergebnisse können aufgrund ungleicher Rahmenbedingungen nicht direkt auf die Gegebenheiten in einem industriellen Produktionsumfeld übertragen werden. Die zu Grunde liegenden Ursachen sind vielfältig. In den meisten Fällen ist etwa ein direkter Messzugang zum Klebstoff bedingt durch die vorhandenen Fügepartner nicht gegeben und Umgebungsbedingungen wie Temperatur und Luftfeuchtigkeit weichen gleichermaßen wie die betrachtete Menge an Klebstoff von den genannten Laborprüfungen ab. Im industriellen Umfeld kaum etabliert, aber im Stand der Technik und Wissenschaft beschrieben, sind hingegen zerstörungsfreie Methoden zur Prüfung von applizierten Klebstoffen. Zu diesen gehören beispielsweise die Terahertz-, berührende Ultraschall- und Kernspinresonanztechnik. Wesentliche Nachteile wie eine nicht berührungslose Arbeitsweise, die die Untersuchung klebriger Oberflächen behindert, eine geringe Eindringtiefe, aus der Informationen gewonnen werden können, einschränkende Anforderungen an die elektrische Leitfähigkeit der untersuchbaren Materialsysteme sowie letztlich hohe Systemkosten sind Gründe für eine geringe Anwenderakzeptanz. Diesen Verfahren steht ein neuer Prüfansatz auf Basis mittels Luftultraschall induzierter, geführter Wellen entgegen. Dieser erlaubt eine verhältnismäßig kostengünstige, wegintegrale Aushärteüberwachung von Klebstoffen über lange Strecken hinweg, ohne einen direkten Zugang zum Klebstoff zu erfordern. Die vorliegende Dissertation erforscht das Messprinzip und die damit verbundenen Vor- und Nachteile, demonstriert unmittelbar die Verfahrenseignung durch Betrachtung unterschiedlicher Klebstoffsysteme, untersucht den Einfluss wesentlicher Prüfrahmenbedingungen, zeigt Anwendungsmöglichkeiten sowie erkannte Limitationen auf und bietet anschließend Umgehungsstrategien zur Überwindung der genannten Limitationen z. B. durch Anwendung von sogenannten Pulskompressionsmethoden an.
Application of capacitive sensors and controlled injection pressure to minimize void formation in resin transfer molding. - In: Polymer composites, ISSN 1548-0569, Bd. 44 (2023), 3, S. 1658-1671
Void formation as a result of irregular resin flow at the flow front is discussed and a practical method for reducing void formation during resin transfer molding (RTM) is introduced. In this study, a sensor system is developed for in situ measurement of resin velocity inside a closed cavity. Assisted by the acquired data, a resin injection system is augmented to automatically adjust the injection pressure and achieve a uniform flow front velocity. It is proven, that the developed system is suited to monitor the resin flow front and is able to sufficiently control flow velocity of a linear flow front. Test specimen produced by this method show significantly reduced void contents in comparison to a common resin transfer molding process.
https://doi.org/10.1002/pc.27195
Optical detection of void formation mechanisms during impregnation of composites by UV-reactive resin systems. - In: Journal of composites science, ISSN 2504-477X, Bd. 6 (2022), 11, 351, S. 1-15
During the impregnation of reinforcement fabrics in liquid composite molding processes, the flow within fiber bundles and the channels between the fiber bundles usually advances at different velocities. This so-called “dual-scale flow” results in void formation inside the composite material and has a negative effect on its mechanical properties. Semi-empirical models can be applied to calculate the extent of the dual-scale flow. In this study, a methodology is presented that stops the impregnation of reinforcement fabrics at different filling levels by using a photo-reactive resin system. By means of optical evaluation, the theoretical calculation models of the dual-scale flow are validated metrologically. The results show increasingly distinct dual-scale flow effects with increasing pressure gradients. The methodology enables the measurability of microscopic differences in flow front progression to validate renowned theoretical models and compare simulations to measurements of applied injection processes.
https://doi.org/10.3390/jcs6110351
Development of a production process for environmentally friendly and resource-efficient molded parts consisting of load-appropriate reinforced wood-plastic composites :
Entwicklung eines Herstellungsprozesses für umweltfreundliche und ressourceneffiziente Formteile aus lastgerecht verstärkten Holz-Kunststoff-Verbunden. - In: Zeitschrift Kunststofftechnik, Bd. 18 (2022), 4, S. 203-233
Dieser Beitrag beschreibt einen Herstellungsprozess für umweltfreundliche und ressourceneffiziente Formteile aus neuartigen Holz-Kunststoff-Verbunden (HKV). Bei der Herstellung von HKV werden anisotrope mechanische Eigenschaften von langen, schlanken Holzspänen (Strands) durch deren lastgerechte Positionierung auf dreidimensionaler Werkzeugoberfläche anwendungsoptimiert ausgenutzt und umweltverträgliche duro- als auch thermoplastische Kunststoffe als Alternative zu den konventionellen formaldehyd- oder isocyanathaltigen Bindemitteln eingesetzt.
https://dx.doi.org/10.3139/O999.01042022
Numerical simulation of the deformation behavior of softwood tracheids for the calculation of the mechanical properties of wood-polymer composites. - In: Polymers, ISSN 2073-4360, Bd. 14 (2022), 13, 2574, insges. 25 S.
From a fiber composite point of view, an elongated softwood particle is a composite consisting of several thousand tracheids, which can be described as fiber wound hollow profiles. By knowing their deformation behavior, the deformation behavior of the wood particle can be described. Therefore, a numerical approach for RVE- and FEM-based modelling of the radial and tangential compression behavior of pine wood tracheids under room climate environment is presented and validated with optical and laser-optical image analysis as well as tensile and compression tests on pine sapwood veneer strips. According to the findings, at 23 ˚C and 12% moisture content, at least 10 MPa must be applied for maximum compaction of the earlywood tracheids. The latewood tracheids can withstand at least 100 MPa compression pressure and would deform elastically at this load by about 20%. The developed model can be adapted for other wood species and climatic conditions by adjusting the mechanical properties of the base materials of the cell wall single layers (cellulose, hemicellulose, lignin), the dimensions and the structure of the vessel elements, respectively.
https://doi.org/10.3390/polym14132574
Wichtiger Wettbewerbsfaktor Thüringer Unternehmen. - In: Wirtschaftsspiegel, ISSN 2190-409X, Bd. 18 (2022), 1, S. 24-25
Berechnung des Elastizitätsmoduls von Verbundwerkstoffen unter Berücksichtigung der Adhäsion an der Faser-Matrix-Grenzfläche : ein Beitrag am Beispiel kurzfaserverstärkter Thermoplaste. - Ilmenau : Universitätsbibliothek, 2022. - 1 Online-Ressource (xx, 216 Seiten)
Technische Universität Ilmenau, Dissertation 2021
In dieser Arbeit wird erstmalig ein Berechnungsmodell für Elastizitätsmoduln von kurzfaserverstärkten Kunststoffen unter Berücksichtigung der werkstoffspezifischen Haftbedingung in der Faser-Matrix-Grenzfläche vorgestellt und validiert. Dies erfolgt im Rahmen einer Modellerweiterung indem die Oberflächenspannungsanteile der Kontaktpartner herangezogen und Oberflächenrauheiten der Fasern vernachlässigt werden. Die Anwendung des Modells präzisiert die Vorhersagen des Elastizitätsmoduls des Verbundes, was direkte Auswirkungen auf die Eigenfrequenzen und Nachgiebigkeit von Bauteilen insbesondere unter Verwendung nahezu unpolarer Matrices hat. Ein einmaliger Vorteil der Modellerweiterung besteht in der Möglichkeit Kreuzvergleiche zwischen den zu kombinierenden Materialien durchzuführen. Kombinationsspezifische Untersuchungen, wie Einzelfaserauszugstests einer spezifischen Faser-Matrix-Kombination, sind nicht mehr notwendig. Die Messung der Oberflächenspannungsanteile der gewählten Materialien erfolgt unter Verwendung dreier Testflüssigkeiten: destilliertes Wasser, Dimethylsulfoxid und Ethylenglycol. Darüber hinaus ist die Messung unter Einsatztemperatur zu empfehlen, die in vielen Fällen im Bereich der Raumtemperatur und im Rahmen dieser Untersuchungen bei 23 ˚C liegt. Zur Sicherstellung einer vollständig ausgeprägten Kontaktfläche zwischen Faser und Matrix muss ein Spreiten der Matrix auf der Faseroberfläche vorliegen. Hierbei muss die Gesamtoberflächenspannung der Matrix stets kleiner sein als die Gesamtoberflächenspannung der Faser oder gleichwertig. Die Modellerweiterung wird anhand geeigneter Faser- und Matrixwahl auf die Effekte der physikalischen Adhäsion reduziert, um dessen Einfluss klar herauszuarbeiten. Die eigenen Untersuchungen zeigen die Abweichungen der etablierten Modelle von bis zu 25 %, die mit der neuartigen Modellerweiterung stets im Bereich der Messunsicherheit des Elastizitätsmoduls des Verbundes aus den Zugversuchen liegen. Schließlich wird die Modellerweiterung an Daten aus der Literatur erprobt. Die Verbesserung der Vorhersage des Elastizitätsmoduls des Verbundes ermöglicht es, bereits in der Konzeptionsphase ein zuverlässiges elastisches Deformationsverhalten vorherzusagen und Materialwechsel oder Funktionsfaktoren im Entwicklungsprozess zu minimieren bis verhindern.
https://doi.org/10.22032/dbt.51472
Kohlefaserrecyclingprozess zu hochgefüllten Langfaserthermoplasten mittels Innenmischer (CFINMISCH) : Schlussbericht : Berichtszeitraum: Oktober 2018-November 2020. - Ilmenau : [Technische Universität Ilmenau]. - 1 Online-Ressource (39 Seiten, 2,83 MB)Förderkennzeichen BMBF 033RK064A-C
https://doi.org/10.2314/KXP:1811025706
Modellbildung und Vorabschätzung für das Betriebsverhalten eines Planetwalzenextruders. - Ilmenau : Universitätsbibliothek, 2021. - 1 Online-Ressource (vi, 143 Seiten)
Technische Universität Ilmenau, Dissertation 2021
Der Planetwalzenextruder hat sich als Spezialist unter den Compoundierextrudern für die Aufbereitung von temperaturempfindlichen Kunststoffen etabliert. Im Vergleich zu anderen Extrusionssystemen ist der Kenntnistand zum Materialtransport, des Energieeintrags und des Aufschmelzens in der Maschine jedoch mangelhaft. Insbesondere analytische Modelle zur Beschreibung des Prozessverhaltens von Planetwalzenextrudern fehlen vollständig. Dies wird bei der Auslegung und Optimierung von Extrusionsprozessen mit dem Planetwalzenextruder durch die steigende Komplexität der Prozesse zunehmend zum Problem. Diese Arbeit zum Thema "Modellbildung und Vorabschätzung für das Betriebsverhalten eines Planetwalzenextruders" soll einen Beitrag zur Lösung dieser Herausforderung liefern. In der vorliegenden Arbeit wird eine mathematische Beschreibung der Geometrie- und Geschwindigkeitsverhältnisse im Planetwalzenextruder entwickelt. Darauf aufbauend werden Modellierungsansätze aus der Ein- und Doppelschneckenextrudertheorie an die Geometrie- und Prozessbedingungen des Planetwalzenextruders angepasst. Hierzu werden die Teilbereiche Materialförderung, Plastifizierung, Temperatur- und Leistungseintrag getrennt modelliert und anschließend gekoppelt. Experimentelle Betrachtungen werden dabei für die Modellbildung und Validierung genutzt. Damit steht ein Simulationswerkzeug zur Verfügung, das wichtige Prozesskenngrößen wie Druck, Temperatur, Aufschmelzgrad, Viskosität, Schergeschwindigkeit und Verweilzeit entlang des Planetwalzenextruders bestimmen und darstellen kann. Für die untersuchten Materialien wird in den Berechnungen eine Vorhersageunsicherheit von etwa 20 % erreicht. Die entwickelten Modelle stellen damit einen ersten Schritt für eine simulationsunterstützte Auslegung von Extrusionsprozessen mit dem Planetwalzenextruder dar.
https://doi.org/10.22032/dbt.50333
Qualitätsorientierte Prozessauslegung im Resin Transfer Molding. - Ilmenau : Universitätsverlag Ilmenau, 2021. - 1 Online-Ressource (257 Seiten). - (Fertigungstechnik - aus den Grundlagen für die Anwendung ; Band 11)
Technische Universität Ilmenau, Dissertation 2021
Resin Transfer Molding (RTM) als Herstellungsverfahren für Faserverbundbauteile bietet die Vorteile kurzer Zykluszeiten und niedriger Fehlstellengehalte in Form von Poren. Die Realisierung dieser beiden Ziele ist jedoch nur möglich, wenn der Einfluss der Prozesskenngrößen auf den Fehlstellengehalt bekannt ist. Hierzu wird in der vorliegenden Arbeit ein Beitrag geleistet. Die Bildung von Poren findet während der Benetzung der Faserbündel an der Fließfront des Harzes statt. Dabei entstehen aufgrund von Permeabilitätsunterschieden sowie der Wirkung des Kapillareffekts Ungleichmäßigkeiten, die zum Einschluss von Luft führen. In bisherigen Untersuchungen wurden zur Abschätzung des Porengehalts stets statische Kenngrößen verwendet und es erfolgte keine ausreichende Berücksichtigung der Bündelgeometrie. Daher können Ergebnisse nicht zur Prozessoptimierung auf konkret vorliegende Fälle übertragen werden. Mit Hilfe hier neu entwickelter Bündeltränkungsmodelle, in denen der dynamische Kontaktwinkel zwischen Harz und Faser erstmals rechnerisch erfasst wird, werden zunächst die Vorgänge an der Fließfront beschrieben. Es wird aufgezeigt, dass der Kapillareffekt bei hohen Tränkungsgeschwindigkeiten nicht mehr vorantreibend, sondern hemmend wirkt. Die Tränkungsmodelle werden in Fehlstellenentstehungsmodelle für sphärische und zylindrische Poren überführt. Ein neuartiges Weibull-Modell liefert dabei die Viskositätsentwicklung des Harzes während der Injektionsphase. Im anschließenden praktischen Teil werden Prozessversuche innerhalb eines Versuchsraums aus unterschiedlichen Preforms durchgeführt, in denen gezielt Poren erzeugt werden. Die vorliegenden Prozesskenngrößen werden in einem Glaswerkzeug in-situ erfasst. Die Gehalte der wesentlichen Fehlstellenarten werden analysiert. Hieraus ergeben sich empirisch ermittelte Anpassungsfaktoren für die Fehlstellenentstehungsmodelle, die von Faserhalbzeug oder Benetzungsrichtung abhängig sind. Die Modelle sind damit auf weitere Halbzeuge übertragbar. Abschließend wird ein Algorithmus zur Bestimmung der Injektionsparameter auf Basis des zu erwartenden Fehlstellengehalts anhand eines Beispielbauteils präsentiert. Dieser gestattet eine Prozessoptimierung, die sowohl eine kurze Zykluszeit als auch einen niedrigen Fehlstellengehalt zum Ziel hat. Somit wird ein kostengünstiger und qualitativ hochwertiger RTM-Prozess ermöglicht.
https://doi.org/10.22032/dbt.47951
High frequency DC-DC converter for an integrated electrical excitation of an axial flux machine with fiber-composite rotor: a multidisciplinary approach. - In: CIPS 2020, (2020), S. 371-376
https://ieeexplore.ieee.org/document/9097711
T11-372 : Influence of oscillating surfaces on the rheological behavior of thermoplastic melt. - In: SPE ANTEC 2018, (2020), S. 1168-1171
Viscosity measurement of polypropylene loaded with blowing agents (propane and carbon dioxide) by a novel inline method. - In: Journal of cellular plastics, ISSN 1530-7999, Bd. 56 (2020), 1, S. 73-88
https://doi.org/10.1177/0021955X19864400
Rheoform - Verbesserte Formgebung in Extrusions- und Spritzgussmaschinen durch Schmelzvibrationsanregung (Zwanzig20 - smart3 - Verbundvorhaben) : Schlussbericht : Laufzeit des Vorhabens: Januar 2017-Juni 2019, Berichtszeitraum: Januar 2017-Juni 2019. - Ilmenau : Technische Universität Ilmenau - Fakultät für Maschinenbau - Fachgebiet Kunststofftechnik. - 1 Online-Ressource (49 Seiten, 2,94 MB)Förderkennzeichen BMBF 03ZZ1013B [richtig] - 03221013B [falsch]
https://doi.org/10.2314/KXP:1692277618
Vorhabenbezeichnung: BioanBak - Antibakteriell modifizierte Kunststoffformteile auf Basis von Kiefernkernholz und Bio-Kunststoffen (KMU-innovativ) : Forschungsbericht : Berichtszeitraum: Dezember 2015-November 2018. - Ilmenau : Technische Universität Ilmenau. - 1 Online-Ressource (33 Seiten, 676,37 KB)Förderkennzeichen BMBF 03XP0036E
https://doi.org/10.2314/KXP:1678655392
Single screw extrusion with low pressurized blowing agents. - In: AIP conference proceedings, ISSN 1551-7616, Bd. 2055 (2019), 070021, insges. 5 S.
https://doi.org/10.1063/1.5084865
Mechanical property model for fiber filled thermoplastics incorporating surface tension. - In: AIP conference proceedings, ISSN 1551-7616, Bd. 2055 (2019), 070014, insges. 6 S.
https://doi.org/10.1063/1.5084858
Characterization of bulk materials for single screw extrusion by means of fluidization testing. - In: AIP conference proceedings, ISSN 1551-7616, Bd. 2055 (2019), 070005, insges. 5 S.
https://doi.org/10.1063/1.5084849
Strategies to preserve bio-based antimicrobial agents during extrusion and injection molding. - In: AIP conference proceedings, ISSN 1551-7616, Bd. 2065 (2019), 030003, insges. 5 S.
https://doi.org/10.1063/1.5088261
Effects of interparticle interactions on the flow behaviour of low density polyethylene filled with various fillers. - In: AIP conference proceedings, ISSN 1551-7616, Bd. 2055 (2019), 040002, insges. 5 S.
https://doi.org/10.1063/1.5084817
Application of desert sands as reinforcing material for polymer concrete. - In: Europe and Africa Regional Meeting of Polymer Processing Society (PPS 2017), (2018), S. 271
Tailored wood strand plastic composites for high performance applications. - In: Europe and Africa Regional Meeting of Polymer Processing Society (PPS 2017), (2018), S. 234
A physical-mathematical model describing the process behaviour of planetary roller extruders. - In: 27th Polymer Processing Society Annual Meeting (PPS-27), (2017), S. 924-930
Analysis of pellet diameter and inorganic filler influences on the polymer melting behavior in planetary roller extruders. - In: AIP conference proceedings, ISSN 1551-7616, Bd. 1914 (2017), 080001, insges. 5 S.
https://doi.org/10.1063/1.5016741
Modelling mechanical properties of glass and basalt fiber filled thermoplastics. - In: 32nd Polymer Processing Society Annual Meeting 2016 (PPS-32), (2017), S. 1081-1085
Filaments and short fibers as fillers are one of the most common ingredients to thermoplastics modification in order to impact on mechanical properties of injection molded parts and maintain cost efficiency at minimum part weight. In this study, glass and basalt fibers are processed into a thermoplastic matrix to compare achievable mechanical property improvements as a result of fiber type, content, length and orientation in various plastic matrix materials. Fibers are processed into the thermoplastics matrix by a twin screw extruder, regranulated and then injection molded into components. Mechanical properties of these components are measured. Results of experimental studies are compared and correlated in order to derive quantitative relationships to be able to predict properties for different material combinations of glass and basalt fibers and a variety of thermoplastics. Major parameters of the model are fiber content, length and orientation as a result of processing conditions. Comparable to the CHAMIS laws, a relationship is established to predict achievable Young´s modulus and tensile strength for both types of fibers used. Based on the material model, a determination of required fiber content, length and orientation is feasible. The desired configuration of the compounded fiber filled material and its alteration in the injection molding process needs to be taken into account to assert the desired property enhancement in the injection molded part. The steps of the process are analyzed and methods to predict fiber length reduction during processing and resulting orientation are comprehended. The study will introduce ways to predict properties of fiber filled thermoplastics more accurately and thus allow comparing glass and basalt fiber effectiveness.
Molecular orientation and residual stresses impact on optical properties of plastic lenses. - In: 32nd Polymer Processing Society Annual Meeting 2016 (PPS-32), (2017), S. 983-987
The substitution of conventional materials such as glass for optical plastics offers a high potential for the realization of complex optical systems. Large-scale production processes in combination with high-grade optical parts can be realized by using an injection molding process. The processing of these plastics parts influences the optical properties due to the fact that physical effects occur during filling and cooling of the melt. In general, the optical properties can be differentiated in inner properties (refractive index, transmittance) and outer properties (surface, dimensional accuracy). Both influence and change the light path through the optical material. This work aims to analyze the processing of plastic lenses by tracing back the processing parameters to the occurring physical effects. In comparison to experiments and simulations, the difference between calculated and analyzed optical properties is presented in detail. For this purpose, lens-shaped test specimen were processed on an injection molding machine with different processing parameters. In the simulation program MOLDEX 3D, birefringence patterns, warpage and shrinkage were analyzed and compared to the experimental data applying polariscope for residual stresses and an integrating sphere for transmittance grade. Transmittance values of the lenses between 88 and 89, 1% were accomplished for a polycarbonate lense. By taking into account the correlation between processing parameters and optical properties, a forecast of birefringence and transmittance of plastic parts is possible.
Modeling approach for the degradation mechanisms of PLA resulting from processing. - In: 32nd Polymer Processing Society Annual Meeting 2016 (PPS-32), (2017), S. 471-475
Groove geometry and bulk material properties impacting on pressure build-up in single screw extruders. - In: 32nd Polymer Processing Society Annual Meeting 2016 (PPS-32), (2017), S. 265-269
Influence of fiber length in basalt fiber filled thermoplastics on mechanical properties. - In: Engineering for a changing world, (2017), insges. 9 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2017iwk-032:5
Influence of fiber undulation on the mechanical properties of fiber reinforced plastics. - In: Engineering for a changing world, (2017), insges. 12 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2017iwk-030:0
Processing and quality of continuous fiber reinforced thermoplastic by direct extrusion. - In: Engineering for a changing world, (2017), insges. 8 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2017iwk-017:9
Influence of flowability and MAH-content of maleated polyolefines on rheological and mechanical interaction effects of wood fillers in polyolefines. - In: Engineering for a changing world, (2017), insges. 10 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2017iwk-093:2
Influence of interparticle interaction effects on the rheological properties of low density polyethylene filled with glass beads. - In: Polymer testing, ISSN 1873-2348, Bd. 62 (2017), S. 440-446
https://doi.org/10.1016/j.polymertesting.2017.07.019
Wood chip plastic composite - a novel bio-based material with high mechanical properties. - In: Polimery, ISSN 0032-2725, Bd. 62 (2017), 7/8, S. 556-559
http://dx.doi.org/10.14314/polimery.2017.556
Rheological characterisation of the flow behaviour of wood plastic composites in consideration of different volume fractions of wood. - In: ic-rmm2, (2017), 012017, insges. 9 S.
https://doi.org/10.1088/1742-6596/790/1/012017
Influence of the filler proportion of boron nitride on the dielectric behaviour of polymeric HVDC cable insulations :
Einfluss des Füllstoffanteils von Bornitrid auf das dielektrische Verhalten von polymeren HGÜ-Kabelisolierstoffen. - In: VDE-Hochspannungstechnik 2016, ISBN 978-3-8007-4310-0, (2016), S. 139-144
Modeling the viscosity development of epoxy resins during injection of the RTM process. - In: AIP conference proceedings, ISSN 1551-7616, Bd. 1779 (2016), 070002, insges. 5 S.
The development of, in particular RTM, processes for fiber reinforced composite parts is driven by cost reduction that can be achieved by shorter cycle times. The main sub processes are the injection and the curing time of the resin. Both depend directly on resin properties. During the injection phase the viscosity of the resin is a main factor for the flow rate. Additionally, the wetting of fibers and within that the void formation is influenced. The cure of the resin is the most time intensive sub process. In this paper a new model for the description of the resin viscosity development during the injection phase using the cumulative Weibull distribution function is presented. A study of the isothermal viscosity development of numerous resins has been conducted in a wide temperature range ascertaining the applicability. New possibilities for advanced resin selection and a more accurate modeling of the void formation during an injection phase of the RTM process are shown to confirm the benefit of this model.
http://dx.doi.org/10.1063/1.4965534
Energy balance analysis of the feed zone of grooved barrel single screw extruders. - In: AIP conference proceedings, ISSN 1551-7616, Bd. 1779 (2016), 030011, insges. 5 S.
The energy balance in the feed zone of grooved barrel single screw extruders is important for design and operation of such extruders. Experimental investigations with different bulk materials were undertaken to obtain further insight into the energy balance of the feed zone. The energy balance considers the enthalpy change resulting from temperature and density increase as a result of screw drive power and heat flow in the barrel. Experimental results show a decreasing solid bed temperature for decreasing residence times. In addition, with a reduced gap in the throttle with constant throughput, the pressure increases resulting into various deformation mechanisms of solid particles. The energy required for the deformation of solid particles into a solid bed elevates the specific screw drive power and heat generation. It is shown that the compression behavior of bulk materials is temperature-dependent and influences the energy balance in the feed zone.
http://dx.doi.org/10.1063/1.4965481
Process parameters affecting the bonding of in-mold decoration of injection molded components. - In: AIP conference proceedings, ISSN 1551-7616, Bd. 1779 (2016), 020008, insges. 5 S.
This paper studies the fundamental parameters affecting bonding strength of injection molded parts by an in- mold decoration process (IMD). In order to investigate the influence of materials used and a variety of processing conditions, a test mold was created for experiments. The impact of each factor was examined quantitatively by a full factorial design of experiment (DOE). The DOE covered as processing parameters melt temperature, mold temperature and packing pressure and for product related parameters film thickness and thermoplastic material. Furthermore, the temperature in the boundary layer was experimentally determined and the thermal conditions calculated with a transient simulation. In addition, the results of the experiment were compared with the simulation.
http://dx.doi.org/10.1063/1.4965459
Effects of fiber orientation on the electrical conductivity of filled plastic melt. - In: AIP conference proceedings, ISSN 1551-7616, Bd. 1779 (2016), 030007, insges. 5 S.
The substitution of conventional materials using technical plastic materials offers a high potential for integration of functions into plastics products. In this context, the light-weight design aspect as well as the simplification of complex production processes can be addressed. As an example, plastics can be modified to transfer an electrical charge by adding conductive particles. The conductivity of these plastic materials depends on the used particle system, processing parameters and part geometry. Today's simulation programs offer the possibility of forecasting fiber orientation in plastic parts as a result of processing. This work analyses the relation between simulated fiber orientation and conductivity in the plastic part. Therefore test specimen were produced on an injection molding machine with different processing parameters. Simulations were executed and the fiber orientation tensor for different processing parameters was calculated. In comparison between simulated and experimentally effected fiber orientation, the possibility of forecasting the electrical conductivity was analyzed and it could be shown that there is a good correlation.
http://dx.doi.org/10.1063/1.4965477
Nutbuchsen und Aufgabegut auf dem Prüfstand : Verarbeitung gemahlener Rezyklate. - In: Plastverarbeiter, ISSN 0032-1338, Bd. 67 (2016), 9, S. 128-130
Formaldehyd- und nacharbeitsarme 3-D-Hochleistungs-Holzspan-Kunststoff-Verbunde (HHKV). - In: Holztechnologie, ISSN 0018-3881, Bd. 57 (2016), 5, S. 12-15
Formaldehyd- und nacharbeitsarme 3D-Hochleistungs-Holzspan-Kunststoff-Verbunde (HHKV). - In: Tagungsband des 17. Holztechnologischen Kolloquiums, (2016), S. 175-182
Hybrid composites of plastic and aluminum foam. - In: 2. Internationale Konferenz Euro Hybrid Materials and Structures, (2016), S. 170-177
https://edocs.tib.eu/files/e01fn16/859763315.pdf
The influence of fiber undulation on the mechanical properties of flat and single curved FRP-laminates. - In: Junior Euromat 2016, ISBN 978-2-8399-1926-5, (2016), Abstract number: 2847, Seite 88
http://nbn-resolving.de/urn/resolver.pl?urn=urn:nbn:ch:bel-573360
Process design for void-minimized liquid composite molding. - In: Junior Euromat 2016, ISBN 978-2-8399-1926-5, (2016), Abstract number: 2639, Seite 55-56
The production of fiber reinforced lightweight components for automotive and aerospace industry in resin transfer molding (RTM) has achieved considerable progress during the last decade. Cycle times were reduced from hours to minutes and processes are being automated continuously. A major obstacle for industrial serial manufacturing is the formation of voids during the process as injection times tend to be reduced. These defects are usually air entrapments in a microscopic scale. Voids can be formed due to inaccurate molds and material handling as well as process inherent circumstances. Two different categories can be classified. Air entrapments can be measured in the fiber bundles and in the flow channels between the bundles. The parameters effecting these voids in resin transfer molding were examined using a glass wall mold and an inline measurement. It could be shown that void formation is frequently a product of unbalanced flow fronts. The conditions for the two classes can be expressed in the dimensionless modified capillary number. Based on the design of experiments method this number was tested on the predictability of void formation during injection in RTM processes. In the experiments a major effect of the fiber reinforcement setup could be detected. By means of additional wetting analyses in a microscopic scale, characteristic flow front shapes were measured. The bundle geometry and the weave pattern were identified as influencing factors on the flow front. These are not included in the modified capillary number leading to a lower quality level. New key numbers were derived implementing these parameters to improve the accuracy of a prediction of void formation. The key numbers were used to create a process simulation based on analytical approaches. An algorithm was implemented that calculates feasible process parameters referring to process boundary conditions and used materials. The viscosity development of the resin is included using a new Weibull approach characterizing the processing ability of the resin. The outputs of the simulation are all necessary parameters for a production of parts with minimum cycle time at a user specified maximum void level. Means to apply these parameters to industrial processes include the volume flow rate control during injection. The selection of fiber reinforcements and resins based on process design aims is assisted. The results are transferable to other processes and enable a faster start-up of production processes for newly designed lightweight components.
http://nbn-resolving.de/urn/resolver.pl?urn=urn:nbn:ch:bel-573360
Application of desert sands for polymer concrete. - In: Junior Euromat 2016, ISBN 978-2-8399-1926-5, (2016), Abstract number: 2853, Seite 43
The refugee crisis has shown that the fast construction of medium-term homes in crisis regions is a major challenge. Particularly in the middle east the lacks of suitable construction sands, energy, water and infrastructure leads to the requirement of novel production methods for building blocks. In the present work, methods for the application of local sands in polymer concrete bricks were developed. The basic conditions and requirements for a concept of a mobile production plant for bricks were analyzed. A layout consisting of standard shipping containers was chosen. A production chain with defined mixtures of cleaned quartz sands, rock flour and polyester resin could be configured to manifacture bricks containing 87 % filling material in an inline-process with a cycle time of less than one hour. The adaption for natural desert sands started with an analysis of variying temperatures and humidity. Sands from multiple countries around the earth were analyzed in rheometer experiments. It could be shown that the curing times depend on the filling sand, preventing a simplified implementation into the established processes. The desert sands were characterized for differences in particle size, particle shape, specific heat capacity and chemical composition. Particle analysis showed that a larger angle of repose leads to fewer void content in the brick. The minor differences of specific heat were not sufficient to inhibit the self-acceleration of the exothermic resin reaction. The divergences of the chemical composition were identified as the most important obstacle. The premise is that available sands should be used. Thus the only possibility was to adapt the mixture of the polyester resin to the filling material. The resin is inhibited to ensure adequate time for wetting the sand. MEKP hardeners were combined with cobalt and cobalt-amine accelerators. The analysis showed that especially cobalt-amine accelerators lead to the pursued cycle time of under 60 minutes. On the other hand a correlation between the metallic elements in the sand and the viscosity increase of the polymer concrete could be obtained. These elements impede the effect of the cobalt complex in the accelerator. Particular ratios of hardener and accelerator for every sand must be applied. A user-friendly fast test was developed that can be performed on site. So the suitability of the resin and the filling material is ensured. The mechanical properties of desert sand and quartz sand polymer concrete were measured in standard devices. The results show that the strength of common polymer concrete can almost be achieved. Desert sand bricks could be used even to build two-storey houses. Based on the examinations a mold concept for the establishment of a series process was derived. The comparatively high shrinkage of the polyester resin and the friction of the sand were taken into account to design a manufacturing mold with a reusable core. It could be shown that the application of desert sands for the production of building blocks is possible. The impacting factors were examined and a concept for a process adapted to the natural resources was established. A mobile production plant can now be built to help diminish the harm of refugees in crisis regions.
http://nbn-resolving.de/urn/resolver.pl?urn=urn:nbn:ch:bel-573360
Schlussbericht zum Wachstumskern LEANTEC-Antrieb : Verbundprojekt 3: Demonstratoren : Teilprojekt 3.3: Extruder mit elektrischem Hauptantrieb. - Ilmenau : Technische Universität Ilmenau, Fachgebiet Kunststofftechnik. - 1 Online-Ressource (36 Seiten, 868,45 KB)Förderkennzeichen BMBF 03WKBY03C. - Verbund-Nummer 01083285
https://edocs.tib.eu/files/e01fb16/860138003.pdf
Das Fachgebiet Kunststofftechnik. - In: Jenaer Jahrbuch zur Technik- und Industriegeschichte, ISSN 2198-6746, Bd. 18 (2015), S. 261-269
Herstellung von 3D-Hochleistungs-Holzspan-Kunststoff-Verbunden (HHKV) in geschlossenen Formwerkzeugen. - In: Technomer 2015, 2015, V 4.3, insges. 3 S.
Kurzfassung S. 51
Korrelation von Eigenschaften und Parametern beim Folienhinterspritzen. - In: Technomer 2015, 2015, V 1.3, insges. 1 S.
Kurzfassung S. 9
The relationship between fibre orientation and electrical conductivity of molded plastic parts. - In: Abstracts of papers, (2015), S. 10-11
Functionalization by adding conductive fibers into thermoplastic matrices offers a transfer of electrical charge through a plastic component. A percolation network can be generated using contacting particles that create conductive paths through insulating thermoplastic. Injection molding parameters influences the generation of this network, thus electrical conductivity. Especially, the particle orientation and distribution result in obtaining a percolation path. To identify the main influences, a processing parameter study was carried out and verified by FEM flow simulation. A comparison of calculated and measured results shows differences resulting from interactions between individual fibers and variant cooling as a result of altered thermal conductivity. The predictability of flow orientation leads to suitable processing conditions to effect electrical conductivity patterns.
Wpływ modifikacji powierzchni na mieszanki pianek metalicznych z materiałami termoplastycznym :
Influences of surface-modifications on metalfoam-thermoplastic compounds. - In: Abstracts of papers, (2015), S. 7
Lightweight hybrid composites of CFRP and aluminum foam. - In: Materials science forum, ISSN 1662-9752, Bd. 825/826 (2015), S. 482-489
http://dx.doi.org/10.4028/www.scientific.net/MSF.825-826.482
Production of 3D parts from wood chips in a closed mold process. - In: Materials science forum, ISSN 1662-9752, Bd. 825/826 (2015), S. 1027-1032
http://dx.doi.org/10.4028/www.scientific.net/MSF.825-826.1027
Design trifft Funktion : Bericht zur Tagung "Folien + Fahrzeug 2015". - In: Kunststoffe, ISSN 0023-5563, Bd. 105 (2015), 5, S. 16-18
Energy efficiency in injection molding. - In: Regional Conference Polymer Processing Society, Graz 2015, (2015), S. 63
Porenfreie Bauteile : Verringerung des Fehlstellengehalts und Prozessbeschleunigung im RTM-Prozess. - In: Lightweight design, ISSN 2192-8738, Bd. 8 (2015), 4, S. 56-61
Das Resin Transfer Molding Verfahren (RTM) zur Herstellung von Leichtbauteilen aus faserverstärktem Kunststoff wird vermehrt in Serienprozessen eingesetzt. Dabei ist stets ein Kompromiss zwischen kurzer Zykluszeit und hoher Bauteilqualität zu suchen. An der TU Ilmenau wurde die Fehlstellenentstehung während des Injektionsvorgangs genauer analysiert und eine veränderte Injektionsstrategie entwickelt. Die Analyse zeigt, dass bei geeigneten Prozessparametern die Herstellung fehlstellenfreier Bauteile möglich ist. Erzielbare Zykluszeiten erleichtern die Produktion in Großserienprozessen.
https://doi.org/10.1007/s35725-015-0032-2
Simulierend modifizieren : geometrische Gestaltung von Reibflächen auf Sand. - In: Plastverarbeiter, ISSN 0032-1338, Bd. 66 (2015), 7, S. 54-55
Analysis of the resin transfer molding (RTM) process for FRP and its process simulation fundamentals. - In: AIP conference proceedings, ISSN 1551-7616, Bd. 1664 (2015), 060010, insges. 5 S.
FRP technologies enable the production of lightweight components. The RTM technique is attractive to obtain vehicle parts with little post-processing in industrial scales. The closed mold process provides a desired freedom in part-design combined with high and reproducible production rates compared to other FRP processes. However, the shorter the mold-closed time the higher the risk to run into quality consistency issues resulting from air entrapments or voids due to degassing. This is a major obstacle to FRP processes in general. Other effects on fiber volume content and surface quality can be detected. These factors can be influenced by the choice of process parameters, thus flow pattern determining capillary forces, resin reaction velocity, reaction and mold temperature and others which can be specifically addressed by the change of simple process parameters. The dominant parameters on capillary forces are identified. Investigations were carried out to reduce mold-closed time to less than 5 minutes with reproducible high quality components with a minimum of voids for a serial production process. The essential process factors of the RTM process are identified and mathematically modeled. In particular, well known effects are comprehended in a quantitative approach that permits to specifically set up an industrial process and optimize achievable quality attributes. The void content in a FRP component is critical to mechanical performance and visual acceptance. The developed and presented process understanding allows to quantitatively predetermine achievable part performance at minimum cycle times. The process trials were conducted using a DOE-approach under consideration of material and process parameters for simple 2D parts. A visualization of the flow pattern in the cavity is presented and compared to the new approach of calculating the flow front development. The analysis shows the impact of principle process parameters on the achievable part quality.
http://dx.doi.org/10.1063/1.4918428
Service performance - key measure for equipment sourcing. - In: PET planet insider, ISSN 1438-9452, Bd. 15 (2014), 10, S. 38-40
High pressure capillary rheometry on wood plastic composites with variation of wood content and matrix polymer. - In: Shaping the future by engineering, (2014), insges. 9 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-170:9
CFRP and aluminum foam hybrid composites. - In: Shaping the future by engineering, (2014), insges. 9 S.
One way to minimize the energy consumption of production processes is to reduce moving masses in machinery. This reduction of mass can be carried out through the exchange of solid material, like steel or aluminum, with hybrid materials. These hybrid materials combine application-oriented different type of materials and their properties. This paper deals with the RTM manufacturing process and FEM simulation of such a hybrid material. By using the sandwich design method two tensile-stiff carbon fiber reinforced plastic (CFRP) layers are connected to a low-density aluminum foam (AF) core in order to produce hereafter parts with high weight-specific bending stiffness. At the beginning of this paper an analytical calculation method on the basis of the beam theory is developed, which allows an estimation of the achievable mechanical properties of the composite. The bending stiffness of such a composite is mainly determined by the outer layer modulus and the gravity axis distance of the outer layers. These findings are incorporated into the development of a FEM model, which allows the simulation of various load cases with selectable composite structure. The challenge in developing this model is the implementation of the material-specific peculiarities. These include the anisotropy of the CFRP layers and the core structure of the AF. An experimental plan is developed by using the DoE method. It allows the determination of the RTM process parameters, which will lead to components with the highest weight-specific bending stiffness. On this account preliminary tests are carried out to identify the usable range of injection pressure, mold temperature and compression pressure of the press. This paper can demonstrate, that the production of CFRP/ AF hybrid material by means of the RTM process is feasible. The first manufactured specimens exhibit no displacement of the fibers and almost no air inclusions. The simulation of CFRP/ AF hybrid material could be implemented. The anisotropy of the CFRP layers can be simulated with the ANSYS fiber fracture software ACP. The structure of the AS core can be mapped with great computational effort. The next step is the execution of the developed experimental plan with an especially designed RTM mold for sandwich composites.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-100:6
The influence of fiber undulation on the mechanical properties of FRP-laminates. - In: Shaping the future by engineering, (2014), insges. 8 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-099:3
Process parameters affecting the quality of functionalized in-mold decoration injection molded composites. - In: Shaping the future by engineering, (2014), insges. 9 S.
This report studies the fundamental parameters affecting the wash-off and the warpage of parts manufactured in in-mold decoration process (IMD). The purpose is to derive a process model for describing the wash-off and the warpage of the parts as a function of the main influencing parameters based on a dimensional analysis. In order to investigate the influence of the materials and various processing conditions, a test mold was created for experiments and simulations were carried out. First of all the main influencing factors have been identified. To quantify the influence of each factor, a full factorial design was used. A DOE of process parameters including injection speed, injection pressure, melt temperature, mold temperature, post-injection pressure and the material were designed and executed. Based on the DOE specimens with a 250 [my]m and 375 [my]m thick PC film and a part thickness of 2 mm and 3 mm made from different thermoplastics were produced. In addition, the results of the experiment were compared with the simulation.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-095:0
Integration of connecting elements in hybrid-composite components. - In: Shaping the future by engineering, (2014), insges. 7 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-089:1
Improvement of tribological properties of plastic compounds. - In: Shaping the future by engineering, (2014), insges. 7 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-084:0
Oxygen and water vapor permeability and required layer thickness for barrier packaging. - In: Shaping the future by engineering, (2014), insges. 11 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-076:8
Manufacturing hybrid lightweight compounds of closed-cell aluminium foam and thermosoftening plastics in injection moulding processes. - In: Shaping the future by engineering, (2014), insges. 8 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-053:0
Simulation of the resin transfer molding process (RTM) by analysis of the process fundamentals. - In: Shaping the future by engineering, (2014), insges. 8 S.
Fiber reinforces plastics (FRP) technologies enable the production of lightweight components. The RTM technique is attractive to obtain vehicle parts with little post-processing in industrial scales. The closed mold process provides a desired freedom in part-design combined with high and reproducible production rates compared to other FRP processes. However, the shorter the mold-closed time the higher the risk to run into quality consistency issues resulting from air entrapments. The acceleration of the process can only be achieved by the knowledge of the fundamental process parameters. The effects of void formation and process speed can be managed to reach progresses in both cycle time and void content. The major mechanism of void formation is the entrapment of air due to flow front inconsistencies. These are generated by the differences of the flow front as a result of advancing forces, viscosity and flow resistances. A faster flow front advancement in the fiber tows results in spherical voids, because air in the flow channel between the tows can be entrapped. On the other hand a faster advance in the flow channels results in cylindrical voids in the tows. Only a balanced flow front could enable a process with low void rates. The resin flow in the channels is primarily driven by the inlet pressure. The flow resistance is low in comparison to the fiber tows where the channel radius has a smaller order of magnitude. In the tows the resin flow is additively caused by the capillary pressure that occurs in the small channels between the fibers in the tow. So the flow behavior of the flow front depends on different factors. The established factors for influencing the RTM cycle are mold temperature, inlet pressure, application of vacuum, resin and fiber volume content. However, the impact of the capillary effect has not been examined sufficiently. Possible factors influencing the wicking are finish of the fiber, weave of the reinforcements and the radius of the tows. In addition all factors may have interdependencies on each other. Process trials were conducted using a DOE-approach under consideration of material and process parameters for simple 2D parts. The analysis shows the impact of principle process parameters on the achievable part quality.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-035:0
Analysis of the process behavior for planetary roller extruders. - In: Shaping the future by engineering, (2014), insges. 11 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-045:7
Influences with regard to the processing of conductive polymers. - In: Shaping the future by engineering, (2014), insges. 7 S.
Technical plastics products offer a high potential for light-weight construction techniques. The research activities for functionalized plastics components increasingly become focused. In complex plastics parts, the integration of materials with different properties plays a key role. Especially, conductive polymers offer the possibility to produce low cost complex plastic components in injection molding processes. Beside the functionalization of parts, conductive polymers are also interesting for the housing of electromagnetic compliance (EMC) devices. The conductivity of these plastics components strongly depends on its processing conditions. On consideration of each step of processing, such as the compounding of the plastic with fibers and a subsequent injection-molding, the main influences on the conductivity are carved out.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-062:9
Simulation and comparison of the pressure profile of fumigated and non-fumigated polymer melts. - In: Shaping the future by engineering, (2014), insges. 8 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-079:4
Reducing the void content and targeting at process acceleration of the RTM-Process by Design of Experiments :
Verringerung des Fehlstellengehalts und Prozessbeschleunigung im RTM-Prozess mittels Design of Experiments. - In: Internationale AVK-Tagung für Faserverstärkte Kunststoffe/Composites in Anbindung an die Fachmessen Composites Europe + Aluminium 2014, (2014), S. 41
Dem RTM-Verfahren wird großes Potenzial zur Senkung der Herstellkosten von Faserverbunden zugeschreiben. Bei einer Prozessbeschleunigung ist jedoch stets mit der Entstehung von Fehlstellen zu rechnen. Diese bilden sich meist durch einen ungleichmäßigen Fließfrontverlauf, der sich aus den Permeabilitäten von Faserbündeln und den Kanälen zwischen den Bündeln sowie der Wirkung des Kapillareffekts ergibt. Das Harz strömt jeweils in einem der Teilbereiche voraus und umschließt dabei Luft. Im Bündel treten zylindrische Poren auf, während zwischen den Bündeln eine sphärische Form detektierbar ist. Der Porenvolumengehalt lässt sich mit Hilfe der Kapillarzahl vorausbestimmen. Bisherige Arbeiten konzentrierten sich auf unidirektionale Faserhalbzeuge. Im Rahmen der Arbeiten wurde an Geweben der Einfluss von Webart, Flächengewicht und Finish auf die Permeabilität und den Porenvolumengehalt untersucht. Dazu wurde die Methode der statistischen Versuchsplanung angewandt, um Wechselwirkungen zwischen den Faktoren erfassen zu können. Die Ergebnisse zeigen, dass eine Anpassung der Kapillarzahl für gewobene Halbzeuge sinnvoll ist.
Key figures for describing and comparing the energy consumption of injection molding processes. - In: 71st annual technical conference of the Society of Plastics Engineers 2013, (2014), S. 538-543
This paper deals with energy consumption data for a broad variety of injection molded parts. An analysis shows that key figures can be derived for comparison and reference purposes and allow the evaluation of the energy efficiency in a part dependent production process. The key figures comprise material properties and part geometries to build a focus relative to these particular part characteristics independent of category or application. This approach goes beyond the widely applied method of examining a machine specific energy consumption data. A significant potential of energy reduction for most analyzed injection molding processes is expected.
Untersuchungen an partikelgefüllten Thermoplasten zur Verbesserung des Verschleiß- und Reibverhaltens von spritzgegossenen Kunststoffbauteilen auf Sand. - In: Beiträge, (2014), insges. 8 S.
Hohe Abrasion und schlechte Reibpartner erhöhen die Anforderungen an Kunststoffreibflächen. Sand ist als ein abrasives Medium und schlechter Reibpartner bekannt und dient hier als Referenzmaterial. Derzeit existieren keine Kunststoffe die tribologische Anforderungen auf Sand zuverlässig standhalten und zugleich niedrige Reibwerte besitzen. Zur gezielten Untersuchung der wirkenden Mechanismen von Reibung und Abrasion wird Polyamid 6.6 spritzgegossen und auf Sandoberflächen getestet. Zur Verbesserung werden gezielt Füllstoffe in das Polyamid eingebettet und deren Tribologieeinflüsse über Versuchspläne analysiert. Der Vortrag behandelt die Einflussnahme der Massenanteile von Polytetrafluorethylen (PTFE), Kurzkohlefasern, Talkum und vier weiteren Füllstoffen auf Polyamid. Hierbei werden anhand von Versuchsplänen Zusammenhänge mechanischer Eigenschaften zu den Abrasions- und Reibmessergebnissen gesucht. Ziel der Untersuchung ist die Angabe der idealen Werkstoffkennwerte für Kunststoffe zur Minderung von Abrasion und Reibung auf Sand.
Benchmarking der bauteilabhängigen Energieeffizienz in der Spritzgießproduktion. - In: Spritzgießen 2014, (2014), S. 53-63
Mit der vorgestellten Vorgehensweise kann in einem ersten Ansatz die Energieeffizienz eines Spritzgießsystem (Maschine, Werkzeug, Bauteil) quantitativ so beschrieben werden kann, dass ein Benchmarking und Vergleich mit anderen Maschinen, Werkzeugen und Formteilen erfolgen kann. Die sich damit ergebenden Möglichkeiten können vielfältig zu einer systematischen Reduzierung des Energiebedarfes eingesetzt werden, bei der immer erkennbar ist, welches weitere Potenzial noch auszuschöpfen sein könnte. Die Grundlage der Messlatte, an der diese Referenzierung erfolgt resultiert aus den physikalisch möglichen Grenzwerten in dieser Arbeit beschrieben wurde.
A mathematical model describing the solid conveying and melting behavior of planetary roller extruders. - In: PPS 29, 2013, S12-304, insges. 5 S.
Book of abstracts S. 176
A novel approach to the design of composite components. - In: PPS 29, 2013, S09-790, insges. 2 S.
Book of abstracts S. 149
Differential drive power calculation for smooth barrel single screw extruders. - In: PPS 29, 2013, S03-73, insges. 3 S.
Book of abstracts S. 35
Current drive power models for single screw extruders with a smooth barrel depend on information like melt film thickness and solid bed width calculated by melting models. The melting process is analyzed towards the similarity of its effects compared to the shear stresses resulting in the screw torque. The screw torque in the melting section can be shown to result from the same effects as described in melting models based on heat conduction and dissipation. Even though, melting models are based on these phase transition mechanisms which are also the dominant factors for the required drive power they have only indirectly been used for drive power calculation in current models. This results in a new approach for differential drive power calculation.
Biokunststoffe für den Einsatz bei technischen Bauteilen im Automobil. - In: TECHNOMER 2013, ISBN 978-3-939382-11-9, 2013, P 2.9, insges. 1 S.
Kurzfassung S. 129
Prozessoptimierung durch Analyse und Simulation der bestimmenden Einflussfaktoren des RTM Prozesses. - In: TECHNOMER 2013, ISBN 978-3-939382-11-9, 2013, V 4.8, insges. 10 S.
Kurzfassung S. 68
Die Herstellung von Leichtbaukomponenten wird durch den Einsatz von endlosfaserverstärkten Kunststoffverbunden ermöglicht. Dabei ist das Resin Transfer Molding (RTM) Verfahren hoch attraktiv, um formfallende Teile zu produzieren. Die in der Regel trocken eingebrachte Faserstruktur oder alternativ vorimprägnierte Preforms werden in ein zweiteiliges Werkzeug eingelegt. Nach Schließen der Form wird Harz in das mit Faserstrukturen gefüllte Formnest injiziert. So wird hohe Designfreiheit für das Bauteil sowie eine im Vergleich zu anderen Verfahren bei der Herstellung von Faserverbunden hohe Ausbringungsrate ermöglicht. Die Herausforderung des industriell schnell ablaufenden Prozesses liegt in der Gewährleistung einer gleichbleibend hohen Bauteilqualität. Diese ergibt sich durch ein Minimum an Luftblasen, einen maximalen Faservolumenanteil sowie geschlossene und glatte Oberflächen. Diese Faktoren werden durch die Wahl der Prozessrandbedingungen, z.B. das Fließverhalten unter Berücksichtigung der Kapillarkräfte, Aushärtungsgeschwindigkeit durch Temperatureinfluss u.v.a., maßgeblich beeinflusst. Die wichtigsten Parameter werden identifiziert. Gleichzeitig besteht das Ziel, die Zykluszeit so weit zu senken, dass das Verfahren für die Herstellung von Automobilkomponenten in Serie attraktiv wird. Dabei strebt man eine Prozesszeit von unter 5 min an, die einer blasenfreien Verarbeitung entgegensteht. Der Beitrag untersucht die Einflussfaktoren auf den Prozess, denen in bisherigen Forschungsarbeiten wenig Beachtung geschenkt wurde. Ziel der Untersuchungen ist die Identifikation der entscheidenden Prozessfaktoren, die in ein ganzheitliches Prozessmodell einfließen, mit dem die Prozesszeit in der geschlossenen Form minimiert wird. Es werden Ansätze zur mathematischen Beschreibung der Zusammenhänge vorgestellt und mit Überlegungen zu einer Veränderung der Prozesskette so kombiniert, dass eine deutliche Reduzierung der "Form geschlossen" Zeit erreicht wird. Die Prozessuntersuchungen wurden in einem statistischen Versuchsplan unter Berücksichtigung geeigneter Material- und Verfahrensparameterauswahl an einfachen Bauteilen durchgeführt, die eine allgemeingültige Aussagekraft auch für komplexe Bauteile ermöglichen. Der Einfluss auf Bauteilqualität und Zykluszeit wird quantifiziert und mit den in der theoretischen Analyse der Prozessbedingungen identifizierten Berechnungsgrundlagen korreliert. Damit steigt die Vorhersagegenauigkeit für eine industriell einsetzbare Prozessauswahl.
Formteilbasierte Kennzahlen zur Beschreibung der Energieeffizienz im Spritzgießverfahren. - In: TECHNOMER 2013, ISBN 978-3-939382-11-9, 2013, V 1.12, insges. 8 S.
Kurzfassung S. 18
Definition von Kennzahlen zur Beschreibung des Energieverbrauchs und der Energieeffizienz im Spritzgießprozess, die es erlaubt, die Charakteristik der Energieverbräuche für eine große Bandbreite von Formteilen miteinander zu vergleichen.
Innovationsfelder der Kunststoffindustrie. - In: Kunststoffe, ISSN 0023-5563, Bd. 103 (2013), 10, S. 28-34
Die Studie hat detailliert die Innovations- und Wachstumsfelder der Kunststoffindustrie herausgearbeitet. Dabei offenbarte sich, dass das gewachsene Selbstverständnis der Branche, das auf der Systematik der Verfahrenstechniken beruht, nicht mehr zeitgemäß ist. Wenn es heute um Wachstumswettbewerb durch Innovation in der Kunststoffindustrie geht, wird Interdisziplinarität zum strategischen Wettbewerbsvorteil.
Duroplast-Zahnräder für Zahnradpumpen. - In: Tagungsband, (2012), S. 273-290
Zahnräder aus Duroplast-Kunststoffen : Entwicklungsschwerpunkte bei Duroplast-Kunststoffzahnrädern. - In: Konstruktion, ISSN 0373-3300, Bd. 64.2012, 5, S. IW8-IW10
Drive power calculation for single screw extruders. - In: Polymeric materials 2012, ISBN 978-3-86829-517-7, (2012), S. 42
This study examines models for calculating the power consumption of conventional single screw extruders (SSE) with smooth barrel and presents an approach to increase the accuracy of calculation.
Innovationsfelder der Kunststofftechnik : Roadmap für die Thüringer Kunststoffverarbeitungsindustrie
1. Aufl.. - Ilmenau : TU Ilmenau, Fachgebiet Kunststofftechnik, 2011. - 108 S. ISBN 978-3-9812489-8-2
Literaturverz. S. 105 - 108
A new closed loop mold temperature control technique by means of online thermography. - In: 69th annual technical conference of the Society of Plastics Engineers 2011, (ANTEC 2011), (2011), S. 1664-1667