Mechanische Eigenschaften von Epoxidharz-Faserverbundwerkstoffen in Abhängigkeit vom Aushärtungsgrad

Translated title of the contribution: Mechanical properties of a carbon-fibre-reinforced epoxy resin as a function of curing degree

Robert Jochen Karpf

Research output: ThesisMaster's Thesis

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Abstract

Within the last decades advanced composite materials gained increasing importance for high performance structural applications. The efficient and economic production of such composite parts is mainly influenced by the processing time and the corresponding curing optimization of the thermoset matrix material. The objective of this master thesis was to characterize thermo-mechanical and fracture mechanical properties of an unidirectional carbon-fiber-reinforced epoxy resin as a function of curing degree. The test program included dynamic mechanical analysis (DMA) and fracture mechanics tests on both neat resin and laminate level in dry and wet material conditions. In addition, the compressive strength was determined for the corresponding laminates. Both, neat resins and the laminates showed a trend in increasing the moisture content from approx. 2.6 to 2.8 m-% with increasing curing degree, whereas the moisture content of the laminates in saturated state were around 60 % lower compared to the neat resin. With regard to the thermo-mechanical properties of both materials (neat resin and laminate) a shift for the glass transition temperatures from approx. 115 °C to 170 °C with increasing degree of cure had been observed. In good accordance with the results on the neat resin level a gradual decrease of the laminate storage modulus values in the glassy state was found in dry and wet conditions with an increasing degree of cure. Regarding the fracture mechanical behavior for both the laminate as well as for the neat resin at least a trend towards higher values for the critical energy release rate GIC with increasing curing degree could be determined. These property changes with increasing curing degree may be the result of a higher molecular mobility within the free volume of the epoxy matrix with the loss of the resin’s low molecular weight components. The comparison of the laminate’s compressive behavior with the neat resin’s storage modulus showed a significant influence of the matrix stiffness on the compressive strength of the composite, both decreasing with increasing curing degree.
Translated title of the contributionMechanical properties of a carbon-fibre-reinforced epoxy resin as a function of curing degree
Original languageGerman
QualificationDipl.-Ing.
Supervisors/Advisors
  • Pilz, Gerald, Supervisor (internal)
Award date29 Jun 2012
Publication statusPublished - 2012

Bibliographical note

embargoed until 05-06-2017

Keywords

  • carbon fiber composites
  • dynamic mechanical analysis
  • epoxy resin
  • fracture toughness
  • curing degree
  • water absorption

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