Effect Of Filler content On Viscoelastic Behaviour Of Epoxy Vitrimer Nanocomposites
Topic(s) : Multifunctional and smart composites
Co-authors :
Barbara Palmieri (ITALY), Fabrizia CILENTO (ITALY), Amendola EUGENIO (ITALY), Michele GIORDANO (ITALY), Alfonso MARTONE (ITALY)Abstract :
Epoxy Vitrimers are gathering attention as a development in the field of more easily re-processable and self-healing thermosets. Incorporating a catalyst should activate the transesterification reaction within the polymeric macromolecule inducing topological modification of the network. Reacting epoxy precursors with suitable anhydrides and acids will promote exchange reactions between esters and beta-hydroxyls, adding the vitrimeric behaviour. The presence of magnetic nanoparticles has been proven to contribute to enhance the flow rate when the dynamic exchange has been triggered. In addition, the modification with nanoparticles contribute to add functional properties to the polymer such as electro-magnetic and thermal conductivity.
In the present work, a commercial epoxy system suitable for CFRP manufacturing has been modified to induce vitrimeric behaviour by exploiting the catalytic activity towards the transesterification reaction of Zn2+ [1,2]. Epoxy vitrimer nanocomposites were manufactured by direct mixing of iron oxide nanoparticles. Nanocomposites were manufactured at different Iron Oxide content (10 wt% and 20 wt%) and their thermomechanical properties have been investigated by dynamic mechanical analyser (DMA), differential scanning calorimetry (DSC), and optical micrograph. In addition, creep experiments were performed to investigate the effect of nanoparticles on the flow rate above the critical “Vitrimeric” temperature (Tv). Isothermal creep tests were carried out under constant load of 0.1 MPa at different temperatures starting from 70° to 250°C. The presence of nanoparticles improves the flow rate compared to the pristine epoxy vitrimer resulting in an effective healing capability. Creep data were analysed by Burger model, the viscosity parameter at temperatures above the glass transition decrease according to the nanoparticles content.
Mechanical tests shows that Iron Oxide nanoparticles act as mechanical reinforcement improving the material stiffness.
Magnetic nanoparticles provide an additional feature to the nanocomposite by enabling the induction heating. The vitrimeric nanocomposite could be employed as a hot melt adhesive controlled by an induction stimulus. To assess the effectiveness of the application CFRP joints were prepared by using the nanocomposite as adhesive layer and its response to induction heating has been proven.
Acknowledgment:
This work has been supported by the Research Project LAMPO (code CDS00750), founded by Ministry of Economic Development. The authors would like to thank M. De Angioletti, F. Docimo, M. R. Marcedula and C. Leone for their support to experiments
In the present work, a commercial epoxy system suitable for CFRP manufacturing has been modified to induce vitrimeric behaviour by exploiting the catalytic activity towards the transesterification reaction of Zn2+ [1,2]. Epoxy vitrimer nanocomposites were manufactured by direct mixing of iron oxide nanoparticles. Nanocomposites were manufactured at different Iron Oxide content (10 wt% and 20 wt%) and their thermomechanical properties have been investigated by dynamic mechanical analyser (DMA), differential scanning calorimetry (DSC), and optical micrograph. In addition, creep experiments were performed to investigate the effect of nanoparticles on the flow rate above the critical “Vitrimeric” temperature (Tv). Isothermal creep tests were carried out under constant load of 0.1 MPa at different temperatures starting from 70° to 250°C. The presence of nanoparticles improves the flow rate compared to the pristine epoxy vitrimer resulting in an effective healing capability. Creep data were analysed by Burger model, the viscosity parameter at temperatures above the glass transition decrease according to the nanoparticles content.
Mechanical tests shows that Iron Oxide nanoparticles act as mechanical reinforcement improving the material stiffness.
Magnetic nanoparticles provide an additional feature to the nanocomposite by enabling the induction heating. The vitrimeric nanocomposite could be employed as a hot melt adhesive controlled by an induction stimulus. To assess the effectiveness of the application CFRP joints were prepared by using the nanocomposite as adhesive layer and its response to induction heating has been proven.
Acknowledgment:
This work has been supported by the Research Project LAMPO (code CDS00750), founded by Ministry of Economic Development. The authors would like to thank M. De Angioletti, F. Docimo, M. R. Marcedula and C. Leone for their support to experiments