Innovative Nanocomposite Structural Adhesives - COTCH
Institution
CRP Henri Tudor
Partenaire(s) :
University of Luxembourg ,
UniversIty Louis Pasteur Strasbourg (F)
Du : 01/01/2009
Au : 31/12/2010
Budget : 301 000,00€
Contact(s) :
Bardon Julien
Progress Summary 2009
This project deals with increasing the thermo-mechanical properties of an aluminum-epoxy-aluminum assembly. First, this is obtained by means of incorporation of functionalized particles into the epoxy matrix. Different spherical metal oxide particles were incorporated into epoxy (diglycidyl ether of bisphenol A (DGEBA) – Diethylenetriamine (DETA) system). It is shown that bad dispersion observed by scanning electron microscopy (SEM) in the case of nanoparticles with low specific surface (high diameter), under 70m2/g, leads to a great decrease of glass transition temperature (Tg) as measured by dynamic mechanical analysis (DMA).
It seems to be independent of the particles composition since two alumina nanopowder are compared and incorporation of the powder with specific surface higher than 70m2/g gives good dispersion and an increased Tg. Both silica and alumina powders with high specific surface gives satisfying results when incorporated into epoxy matrix. However, reaction of basic DETA with aluminum substrate leads to dissolution of aluminum and aluminum-DETA complex formation into the epoxy. Therefore, it is not possible to study interphase formation by detecting aluminum element when alumina particles are also incorporated into the epoxy. Then, silica powder is chosen and silica nanoparticles are functionalized and incorporated into epoxy matrix.
Functionnalization of silica particles is performed with 3 different precursor molecules : 3-AminoPropylTriEthoxySilane (APTES), 3-GlycidoxyPropylTriMethoxySilane (GPTMS) and Epichlorohydrine (E). Grafting of amine groups for APTES and epoxy groups for GPTMS and E is respectively performed on silica nanoparticles. SEM observations show that dispersion is qualitatively improved when functionalized particles are compared to raw particles. Epoxy polymer with particles incorporation shows a slight but significative increase of Tg as measured by DMA when functionalization is performed. Best improvement is observed for GPTMS and APTES as compared with E functionalization.
However, it is unclear whether different results from GPTMS and E comes from the different length of the molecule or from the different functionalization rate. Second, improvement of adherence in an aluminum-epoxy system is performed by means of surface modification of aluminum substrate before adhesive bonding. The effect of surface modification by atmospheric pressure plasma treatment is described in article (2). Furthermore, an innovative method to characterize the interphase created in such assemblies is given in article (1).
Refereed Scientific Publications
- (1)“Characterization of the interphase in an aluminium/epoxy joint by using controlled pressure scanning electron microscopy coupled with an energy dispersive X-ray spectrometer” C. Sperandio, C. Arnoult, A. Laachachi, J. Di Martino, D. Ruch
- (2)“Influence of plasma surface treatment on bond strength behavior of an adhesively bonded aluminum-epoxy system”. C. Sperandio, J. Bardon, A. Laachachi, H. Aubriet, D. Ruch. Submitted to : International Journal of Adhesion and Adhesives (2009)
Other Publications
- « Améliorer la tenue mécanique des assemblages collés aluminium/résine époxyde/aluminium par greffage de nanoparticules fonctionalisées et traitement de surface des substrats ». In technical newsletter « material news 1» (September 2009) edited by AMS department of CRP Henri Tudor. This newsletter is transferred to industry customers.