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1143-KK02-04

TOLUENE DIFFUSION IN CONDUCTIVE NANOCOMPOSITE POLYMER, SWELLING BEHAVIOR AND MODELING

S.Thevenot, P.Salagnac, P.Glouannec and J.F.Feller (1)Laboratory material engineering (LIMATB), université européenne de Bretagne (UEB), Lorient, France

ABSTRACT Electrically Conductive Polymer nanocomposites have attracted lots of attention in the last years, especially for their sensitivities to external solicitations, like temperature or pressure variation. This work concerns the modelling of toluene diffusion behaviour in poly(ethylene-co-ethyl acrylate) (EEA)-carbon nanoparticles (CNP) CPC. One of the main objective of our work was to control and model the physical mechanisms involved in this type of material during sorption and desorption phases in the presence of solvent vapour. Two approaches was explore, thin layer to study quick electrical response and thick layer to look after swelling effect induces by toluene. The thick layer mass measurement was compare with our diffusion model. INTRODUCTION Using conductive polymer nanocomposites (CPC) to detect chemical environment is know to be a good way. Sensing applications of CPC is documented in literature [1, 4]. We investigate thin sample and electrical response in toluene vapour to show influence of saturated vapour percent. This is way to now different diffusion mode. Then seeming clustering effect for high partial pressure of solvent confirms interest of multi parameter record experiment. We also investigated the swelling effect induced by toluene vapour and in a first step only desorption. That permits to studying specific behaviour of swelling. Then experimental result permit feed models. A multi-physics knowledge model taking into account diffusion/swelling couplings has been developed to predict desorption kinetics with the Fick’s law. Transfers are considered here as unidirectional due to the important size of main dimensions of the sample compared to its thickness. Parameters such as diffusion coefficient and activity are modelled from experimental data from the literature [2]. Simulations give mass loss behaviour in desorption and are compared to experimental results.

EXPERIMENTAL DETAILS Using material was: 37% w/w carbon nanoparticles filled poly(ethylene-co-ethyl acrylate) (EEA-37CB) from Borealis, EEA 15% ethyl acrylate from Dupont De Nemours, carbon nanoparticles (carbon black operation ENSACO 250G) from Erachen Comilog. The high content of carbon nanoparticles permit to increase precision of measurement to high solvent vapour. Thin samples were preparing layer by layer with a spray system from a polymer solution in toluene (toluene 99% from Acros organics). 200mg EEA and nanofiller some percent w/w was dilute in 20ml of toluene during four hour in ultrasonic bath at eighty degree Celsius. Thin layers were deposing on a micro electrodes then a thermal cycle was apply (10 min at 20°C then up to 110°C and down to 20°C in 3 hour four time).

This dry samples and relax internal strength. Draying samples was exposing to a flux with different conte