Surface energetics of carbon fibers and its effects on the mechanical performance of CF/EP composites

F. Hoecker, J. Karger-Kocsis

Research output: Contribution to journalArticle

81 Citations (Scopus)

Abstract

To exploit the reinforcement potential of the fibers in advanced composites, it is necessary to reach a deeper understanding on the interrelations between fiber surface chemical and energetic characteristics, wetting properties, and mechanical performance. In this study CF/EP was chosen as a model thermoset composite material, whereby a hot-curing epoxy (EP) system served as the matrix. The fibers selected were PAN-based high-tenacity carbon fibers (CF) of varying surface treatment level and/or coating. Surface free energies for the carbon fibers were determined by dynamic contact angle measurements in a variety of test liquids of known polar and dispersive surface tension utilizing a micro-Wilhelmy wetting balance and following the methods proposed by Zisman and Owens and Wendt, respectively. Surface treatment resulted in an increase of the polar fraction of the fiber surface free energy, whereas its dispersive part remained unaffected. The interfacial shear strength (IFSS) as determined in the microdroplet pull-off test was enhanced both by intensification of the surface treatment and sizing the CF with an EP component. A linear relationship between IFSS and the polar fraction of the fiber surface free energy γps was found. Further attempts were made to find correlations between surface free energy of the CF and laminate strengths measured in shear and transverse tension.

Original languageEnglish
Pages (from-to)139-153
Number of pages15
JournalJournal of Applied Polymer Science
Volume59
Issue number1
Publication statusPublished - Jan 3 1996

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Carbon fibers
Free energy
Fibers
Composite materials
Surface treatment
Shear strength
Wetting
Tenacity
Thermosets
Angle measurement
Contact angle
Laminates
Surface tension
Curing
Reinforcement
carbon fiber
Coatings
Liquids

ASJC Scopus subject areas

  • Polymers and Plastics

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Surface energetics of carbon fibers and its effects on the mechanical performance of CF/EP composites. / Hoecker, F.; Karger-Kocsis, J.

In: Journal of Applied Polymer Science, Vol. 59, No. 1, 03.01.1996, p. 139-153.

Research output: Contribution to journalArticle

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