UNDERSTANDING CURE INHIBITION IN CARBON FIBER REINFORCED VINYL ESTER RESIN COMPOSITES
Open Access
- Author:
- Tweed-Kent, Sean Patrick
- Graduate Program:
- Materials Science and Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- October 03, 2008
- Committee Members:
- Thomas David Juska, Thesis Advisor/Co-Advisor
James Patrick Runt, Thesis Advisor/Co-Advisor
Thomas David Juska, Thesis Advisor/Co-Advisor - Keywords:
- FTIR
NEXAFS
XPS
DSC
inhibit
free radical
cure
inhibition
composite
composites
carbon fiber
vinyl ester
differential scanning calorimetry
x-ray photoelectron spectroscopy
near edge X-ray absorption fine structure - Abstract:
- The effect of neat and oxidized carbon fiber reinforcements on vinyl ester resin free radical polymerization was investigated. First, the free radical polymerization of neat vinyl ester resin, vinyl ester resin reinforced by neat carbon fibers, and vinyl ester resin reinforced by oxidized carbon fibers was analyzed with DSC. Neat carbon fibers, and to a greater extent oxidized carbon fibers, were observed to inhibit vinyl ester cure. Second, the surface chemistry of neat and oxidized carbon fibers was analyzed with XPS, NEXAFS, and ATR-FTIR. The surface characterization of neat carbon fibers identified carbon, oxygen, nitrogen, and several trace elements, including silicon, sodium, chlorine, sulfur, magnesium, and calcium. Neat carbon fiber spectra provided evidence for the presence of hydroxyls, ethers, carbonyls, oxidized nitrogen, nitrogen bound to carbonyls, quaternized nitrogen, and non-quaternized nitrogen. The most significant impact of oxidation on carbon fiber surface chemistry was the increase in features indicative of hydroxyls, carbonyls, and non-quaternized nitrogen. These functional groups are present on common inhibitors of free radical polymerization, such as phenols, quinones, and aromatic nitro-compounds, and are likely the cause of the vinyl ester resin cure inhibition observed with DSC.