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  4. Curing kinetics and thermomechanical properties of latent epoxy/carbon fiber composites
 
conference paper

Curing kinetics and thermomechanical properties of latent epoxy/carbon fiber composites

Vacche, S. Dalle
•
Michaud, V.  
•
Demierre, M.
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2016
37th Riso International Symposium on Materials Science
37th Riso International Symposium on Materials Science - Understanding Performance of Composite Materials - Mechanisms Controlling Properties

In this work, resins based on diglycidyl ether of bisphenol A (DGEBA) epoxy and a latent hardener, dicyandiamide (DICY), as well as carbon fiber (CF) composites based on them, were prepared with three commercial accelerators: a methylene bis (phenyl dimethyl urea), a cycloaliphatic substituted urea, and a modified polyamine. The curing kinetics of the three DGEBA/DICY/accelerator systems were investigated by chemorheology and differential scanning calorimetry (DSC), in isothermal and over temperature change conditions. Differences in the reaction onset temperature, and in the glass transition temperature (T-g) were highlighted. For curing of thick resin samples, a slow curing cycle at the lowest possible temperature was used, followed by high temperature (160 - 180 degrees C) post-curing. Indeed, fast curing at higher temperatures caused the formation of hot spots and led to local burning of the samples. The obtained thermomechanical properties, assessed by ultimate tensile testing and dynamic mechanical analysis (DMA) in single cantilever configuration, were all in the expected range for epoxy resins, with tensile moduli close to 3 GPa and T-g > 140 degrees C. The long-term stability of these resins at room temperature was verified by DSC. Composite samples were prepared by hand lay-up by manually impregnating four layers of 5-harness satin CF textile, and curing in vacuum bag. Impregnation quality and void content were assessed by optical microscopy. The flexural properties of the post-cured composites were assessed by three-point bending test at room temperature and showed no relevant differences, all composites having bending moduli of 45 - 50 GPa. Finally, composites cured with a faster high temperature curing cycle (20 min at 140 degrees C) were prepared with the DGEBA/DICY/methylene bis (phenyl dimethyl urea) system, obtaining similar properties as with the slower curing cycle, showing that the prepreg system allowed more flexibility in terms of curing cycle than the bulk resin samples.

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Type
conference paper
DOI
10.1088/1757-899X/139/1/012049
Web of Science ID

WOS:000392730000049

Author(s)
Vacche, S. Dalle
Michaud, V.  
Demierre, M.
Bourban, P-E
Manson, J-A E.
Date Issued

2016

Publisher

Iop Publishing Ltd

Publisher place

Bristol

Published in
37th Riso International Symposium on Materials Science
Total of pages

8

Series title/Series vol.

IOP Conference Series-Materials Science and Engineering

Volume

139

Start page

012049

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
LPAC  
Event nameEvent placeEvent date
37th Riso International Symposium on Materials Science - Understanding Performance of Composite Materials - Mechanisms Controlling Properties

Riso, DENMARK

SEP 05-08, 2016

Available on Infoscience
March 27, 2017
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/136035
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