Applicability of FT-IR Techniques and Goniometry on Characterization of Carbon Fiber Surfaces

Authors

  • Mauro Santos de Oliveira Junior Universidade Federal de São Paulo; Instituto Tecnológico de Aeronáutica
  • Milton Faria Diniz Instituto de Aeronáutica e Espaço
  • Rita de Cássia Lazzarini Dutra Instituto Tecnológico de Aeronáutica; Instituto de Aeronáutica e Espaço
  • Marcos Massi Universidade Federal de São Paulo; Instituto Tecnológico de Aeronáutica
  • Choyu Otani Instituto Tecnológico de Aeronáutica

Keywords:

carbon fibers, composite materials, hydrophobicity, infrared spectroscopy, interfaces, surface properties.

Abstract

Carbon fibers have been widely used as structural reinforcement in aeronautical composites, because of their exceptional mechanical properties. However, carbon fibers present few polar groups on their surfaces inducing a weak interaction with some thermosetting and thermoplastic matrices. Surface treatments, such as thermal and electrochemical oxidation, are generally followed by sizing in order to improve interfacial adhesion between carbon fibers and some matrices. The precise surface characterization, by means of its chemical groups and radical identification, has been pointed out as an effective tool of carbon fibers finishing assessment process. Goniometry and Fourier transforminfrared spectroscopy are widely used to characterize some materials applied in industry, but not for carbon fibers, mainly because of their filamentary shape and the high concentration of carbon even in their near surface. In this paper, unsized and sized Torayca T300 carbon fibers were characterized by goniometry tests to evaluate hydrophilic or hydrophobic character. Qualitatively, it was noticed the effect of sizing on carbon fibers by their hydrophilic behavior, which has not been observed in unsized samples. Chemical analysis was performed by Fourier transform-infrared spectroscopy using different setups: photoacoustic, attenuated total reflectance and universal attenuated total reflectance. The Fourier transform-infrared spectroscopy/ attenuated total reflectance/Germanium was shown to be the most promising technique to analyze carbon fibers surface, despite the low level of relative intensities of some bands. By this technique, it was possible to observe differences between unsized and sized carbon fibers spectra.

Author Biographies

Mauro Santos de Oliveira Junior, Universidade Federal de São Paulo; Instituto Tecnológico de Aeronáutica

Instituto de Ciência e Tecnologia, Universidade Federal de São Paulo - São José dos Campos/SP

Departamento de Física - Divisão de Ciências Fundamentais - Instituto Tecnológico de Aeronáutica - São José dos Campos/SP

Milton Faria Diniz, Instituto de Aeronáutica e Espaço

Divisão de Química - Instituto de Aeronáutica e Espaço - São José dos Campos/SP

Rita de Cássia Lazzarini Dutra, Instituto Tecnológico de Aeronáutica; Instituto de Aeronáutica e Espaço

Divisão de Engenharia Mecânica - Instituto Tecnológico de Aeronáutica - São José dos Campos/SP

Divisão de Química - Instituto de Aeronáutica e Espaço - São José dos Campos/SP

 

Marcos Massi, Universidade Federal de São Paulo; Instituto Tecnológico de Aeronáutica

Instituto de Ciência e Tecnologia, Universidade Federal de São Paulo - São José dos Campos/SP

Departamento de Física - Divisão de Ciências Fundamentais - Instituto Tecnológico de Aeronáutica - São José dos Campos/SP

Choyu Otani, Instituto Tecnológico de Aeronáutica

Departamento de Física - Divisão de Ciências Fundamentais - Instituto Tecnológico de Aeronáutica - São José dos Campos/SP

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Published

2016-03-07

Issue

Section

Original Papers