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Effects of post-curing on the thermo-mechanical behavior and the chemical structure of highly filled phenolic molding compounds

  • Thomas Scheffler , Sascha Englich , Ulrich Heyne and Michael Gehde
Published/Copyright: December 24, 2015
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Materials Testing
From the journal Materials Testing Volume 58 Issue 1

Abstract

Due to their excellent thermomechanical properties, as well as their good media resistance, phenolic molding compounds are outstanding materials for high temperature applications, such as components for the engine compartment. An additional post-curing process, after injection molding, shifts the glass transition temperature towards high temperatures up to 300 °C. The objective of this work is to analyze the influence of the post-curing process on the chemical structure of the material. This structure is responsible for the mechanical and thermal properties of the material. Therefore tensile test bars were molded with a highly filled phenolic molding compound and different post-curing cycles under different atmospheres were done. The tensile properties and the glass transition temperatures (TMA) were measured. To get detailed information of the chemical structure ATR-FTIR and NMR analyses were done. The mechanical properties decreased up to 25 % with higher post-curing temperature (under air atmosphere) although the glass transition temperatures (TMA) and the grades of curing (NMR) increased. Furthermore, in the ATR-FTIR measurements, oxidation products were detected on the surface of the sample which were post-cured under air atmosphere. In comparison, no oxidation products could be detected on the samples post-cured under nitrogen atmosphere and the mechanical properties just decreased about 4 %. Oxidation processes could be provided by post-curing under nitrogen atmosphere which led to higher mechanical properties, in connection with a high grade of cure and a higher glass transition temperature in comparison with post-curing under air atmosphere.

Kurzfassung

Phenol-Formaldehyd-Harz-Formmasssen eignen sich unter anderem aufgrund der sehr guten thermomechanischen Eigenschaften und der guten Medienbeständigkeit hervorragend für den Einsatz im Hochtemperaturbereich, zum Beispiel im Motorraum. Durch eine an den Spritzgussprozess angeschlossene Temperung kann die Glasübergangstemperatur zu Temperaturen über 300 °C verschoben werden. Das Ziel dieser Arbeit ist es, den Einfluss des Temperprozesses auf die chemischen Eigenschaften zu untersuchen, da sowohl die mechanischen als auch die thermischen Eigenschaften direkt abhängig von der chemischen Struktur sind. Es wurden Zugstäbe aus einer hoch glasfaserverstärkten Phenolharzformmasse gespritzt und diese verschiedenen Temperzyklen unter unterschiedlichen Atmosphären ausgesetzt. Anschließend wurden mechanische Zugeigenschaften und die thermischen Glasübergänge gemessen, und um detailliertere Informationen zur chemischen Struktur zu erhalten, wurden ATR-FTIR- und nmR-Untersuchungen durchgeführt. Obwohl die Glasübergangstemperaturen (TMA) und die Aushärtegrade (NMR) stiegen, verschlechterten sich die mechanischen Eigenschaften mit höherer Tempertemperatur (unter Luftatmosphäre) um bis zu 25 %. Des Weiteren konnten bei den Proben, welche unter Luftatmosphäre getempert wurden, Oxidationsprodukte auf der Oberfläche mittels ATR-FTIR Spektroskopie detektiert werden. Im Vergleich dazu konnte bei den Proben, welche unter Stickstoffatmosphäre getempert wurden, keine Oxidationsprodukte auf der Oberfläche beobachtet werden und es kam zu einer geringeren Verschlechterung der mechanischen Eigenschaften (4 %). Durch eine Temperung unter Stickstoffatmosphäre können Oxidationsprozesse auf der Bauteiloberfläche vermieden und somit höhere mechanische Eigenschaften, in Verbindung mit einem höheren Aushärtegrad und einer höheren Glasübergangstemperatur, im Vergleich zur Temperung unter Luftatmosphäre, erreicht werden.

§Correspondence Address, MSc Thomas Scheffler, Professur Kunststoffe, Institut für Fördertechnik und Kunststofftechnik, Technische Universität Chemnitz, Reichenhainer Str. 70, 09126 Chemnitz, Germany. E-mail:

MSc Thomas Scheffler, born in 1987, studied Engineering at Technical University Chemnitz, Germany with focus on plastics. Since 2012, he has been working as Research Assistant at the Chair of Plastics Engineering of TU Chemnitz in the area of thermoset processing and thermal analysis of plastics.

Dipl.-Ing. Sascha Englich, born in 1980, studied Mechanical Engineering at Technical University Chemnitz, Germany with focus on plastics engineering. He has been working as Research Assistant at the Chair of Plastics Engineering of TU Chemnitz since 2007. He is the leader of the working group dealing with injection molding technology.

Dipl.-Ing. Ulrich Heyne, born in 1980, studied Mechanical Engineering at Technical University Chemnitz, Germany. Since 2012, he has been working as Research Assistant at the Chair of Plastics Engineering of TU Chemnitz in the area of thermoset processing and composites.

Prof. Dr.-Ing. Michael Gehde, born in 1956, graduated in 1993 from University of Erlangen-Nuremberg, Germany. His thesis focused on the extrusion welding of polypropylene. He has been the leader and holder of the Chair of Plastics Engineering at Technical University Chemnitz since 2005.

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Published Online: 2015-12-24
Published in Print: 2016-01-05

© 2016, Carl Hanser Verlag, München

Articles in the same Issue

  1. Inhalt/Contents
  2. Contents
  3. Fachbeiträge/Technical Contributions
  4. Quantification of vanadium precipitates in HSLA steel by synchrotron X-ray absorption spectroscopy (XAS)
  5. Optimization of the wear behavior of uncoated, TiN and AlTiN coated cold work tool steel 1.2379 using response surface methodology
  6. Sensitivity analysis of the residual stress state in friction stir welding of high strength aluminum alloy
  7. Probability of detection of minute defects by ultrasonic automated testing equipment in view of Bayesian inference
  8. Parameters in lock-in thermography of CFRP laminates
  9. Effect of tool material on microstructure and mechanical properties in friction stir welding
  10. Microstructures of an AZ61 wrought magnesium alloy fabricated by a novel SPD process using thermomechanical simulation
  11. Corrosion resistance and microstructure of alloy 625 weld overlay on ASTM A516 grade 70
  12. Effects of post-curing on the thermo-mechanical behavior and the chemical structure of highly filled phenolic molding compounds
  13. Effect of pressing temperature on the wear resistance of a Co-based Cr-Mo powder alloy produced by hot pressing
  14. Deep micro-hole drilling of Hardox 500 by electro-discharge machining
  15. Optimization of thin-wall structures using hybrid gravitational search and Nelder-Mead algorithm
  16. Structural design of vehicle components using gravitational search and charged system search algorithms
  17. Electrical resistivity and strength properties of sodium hydroxide contaminated soil solidified with cement
https://doi.org/10.3139/120.110810

Articles in the same Issue

  1. Inhalt/Contents
  2. Contents
  3. Fachbeiträge/Technical Contributions
  4. Quantification of vanadium precipitates in HSLA steel by synchrotron X-ray absorption spectroscopy (XAS)
  5. Optimization of the wear behavior of uncoated, TiN and AlTiN coated cold work tool steel 1.2379 using response surface methodology
  6. Sensitivity analysis of the residual stress state in friction stir welding of high strength aluminum alloy
  7. Probability of detection of minute defects by ultrasonic automated testing equipment in view of Bayesian inference
  8. Parameters in lock-in thermography of CFRP laminates
  9. Effect of tool material on microstructure and mechanical properties in friction stir welding
  10. Microstructures of an AZ61 wrought magnesium alloy fabricated by a novel SPD process using thermomechanical simulation
  11. Corrosion resistance and microstructure of alloy 625 weld overlay on ASTM A516 grade 70
  12. Effects of post-curing on the thermo-mechanical behavior and the chemical structure of highly filled phenolic molding compounds
  13. Effect of pressing temperature on the wear resistance of a Co-based Cr-Mo powder alloy produced by hot pressing
  14. Deep micro-hole drilling of Hardox 500 by electro-discharge machining
  15. Optimization of thin-wall structures using hybrid gravitational search and Nelder-Mead algorithm
  16. Structural design of vehicle components using gravitational search and charged system search algorithms
  17. Electrical resistivity and strength properties of sodium hydroxide contaminated soil solidified with cement
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