000227067 001__ 227067
000227067 005__ 20180317094945.0
000227067 0247_ $$2doi$$a10.1088/1757-899X/139/1/012049
000227067 022__ $$a1757-8981
000227067 02470 $$2ISI$$a000392730000049
000227067 037__ $$aCONF
000227067 245__ $$aCuring kinetics and thermomechanical properties of latent epoxy/carbon fiber composites
000227067 260__ $$aBristol$$bIop Publishing Ltd$$c2016
000227067 269__ $$a2016
000227067 300__ $$a8
000227067 336__ $$aConference Papers
000227067 490__ $$aIOP Conference Series-Materials Science and Engineering
000227067 520__ $$aIn 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.
000227067 700__ $$aVacche, S. Dalle
000227067 700__ $$0240384$$aMichaud, V.$$g113157
000227067 700__ $$aDemierre, M.
000227067 700__ $$aBourban, P-E
000227067 700__ $$aManson, J-A E.
000227067 7112_ $$a37th Riso International Symposium on Materials Science - Understanding Performance of Composite Materials - Mechanisms Controlling Properties$$cRiso, DENMARK$$dSEP 05-08, 2016
000227067 773__ $$j139$$q012049$$t37th Riso International Symposium on Materials Science
000227067 909CO $$ooai:infoscience.tind.io:227067$$pSTI$$pconf
000227067 909C0 $$0252590$$pLPAC$$xU13295
000227067 917Z8 $$x105657
000227067 937__ $$aEPFL-CONF-227067
000227067 973__ $$aEPFL$$rREVIEWED$$sPUBLISHED
000227067 980__ $$aCONF