PROPRIETES THERMIQUES ET ELECTRIQUES DES NANO ET MICROCOMPOSITES. Abderrahim BOUDENNE Université Paris-Est Créteil (UPEC)/CERTES France

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1 PROPRIETES THERMIQUES ET ELECTRIQUES DES NANO ET MICROCOMPOSITES Abderrahim BOUDENNE Université Paris-Est Créteil (UPEC)/CERTES France Journée Thématique SFT, Paris 8 janvier

2 Composites polymères/charges Charges conductrices conductrices Charges isolantes métallisées PP/Cu EVA/Wollastonite-Ag PVC/MWCNT HDPE/PA-Ag 2

3 Composites polymères/charges conductrices Modélisation λ de la charge EVA/Wollastonite-Ag HDPE/PA-Ag 3

4 Composites polymères/charges conductrices Modélisation λ des composites Modèles numériques Effet de la concentration en charges Effet de la résistance de contact 4

5 Biocomposites et matériaux à base de fibres naturelles Composites à matrices polymères/fibres naturelles Fibres: Ananas, Banane, Sisal, 5

6 Biocomposites et matériaux à base de fibres naturelles Composites à matrices minérales/fibres naturelles FPD: Fibres de Palmier Dattier 6

7 Abderrahim BOUDENNE Université Paris-Est Créteil (UPEC)/CERTES France Journée Thématique SFT, Paris 8 janvier

8 Polymers are materials with low value of thermal conductivity 0.15 k 0.5 [Wm -1 K -1 ] Increase thermal properties for industrial applications Combine polymeric matrix with conductive fillers Develop new materials with properties adapted to specific applications 8

9 Polymer Composites with conductive fillers: Bibliographic Statistics Source: Web of Knowledge (Thomson Reuters 2014) N of publications Year 9

10 Aims How optimize the conductive properties of polymer composite materials? Use an electric and magnetic field during the preparation of the composites 10

11 Matrix: Silicone Rubber Fillers: Ni (10µm) Samples preparation From 0 to 35% vol. Ni in Silicone Rubber Matrix 11

12 Matrix: Silicone Rubber Fillers: Ni (10µm) Micrograph structure With magnetic field Without magnetic field 12

13 Thermophysical behavior Specific heat capacity 1.4 Silicone/Ni // Silicone/Ni random cp (J.Kg -1.K -1 ) Silicone/Ni _I_ Rule of mixtures No effect of Ni distribution Zoom 0.6 Effect of Ni Ni weight (%) 13

14 Thermophysical behavior Thermal Conductivity 2.0 Thermal conductivity (W.m -1.K -1 ) Experimental data Silicone/Ni // Silicone/Ni random Silicone/Ni _I_ Thermal conductivity experimental setup based on (HGP) method Ni vol. (%) 14

15 Thermophysical behavior Thermal Conductivity Thermal diffusivity Thermal conductivity (W.m -1.K -1 ) Experimental data Silicone/Ni // Silicone/Ni random Silicone/Ni _I_ Ni vol. (%) Thermal diffusivity (m 2.s) x Experimental data Silicone/Ni // Silicone/Ni random Silicone/Ni _I_ Ni vol. (%) Effect of Ni vol. (%) Effect of Ni distribution Same behavior (thermal conductivity and diffusivity) 15

16 Thermophysical behavior Thermal Conductivity Low Ni vol. Poor chain-like structure without magnetic field High spatial anisotropy High Ni vol. Spatial distribution of Ni tends to be almost the same Less effect of magnetic field Normalised thermal conductivity Low Ni vol. Max enhance 15% vol. High Ni vol. k Silicone/Ni// k Silicone/Nirandom Ni vol.(%) 16

17 Thermophysical behavior Thermal Conductivity models Lichtenecker s model Agreement with measured values (, random) until 10 % vol. Ni // > 25%vol. experimental values approximate Lichtenecker's model Thermal conductivity log(k/k m ) (1) (3) Ni vol. (%) Silicone/Ni // Silicone/Ni random Silicone/Ni _I_ (1) Parallel model (2) Series model (3) Lichtenecker model (2) Structure effect with gradual reduction of λ when Ni increase 17

18 Electrical behavior Non conductive part Conductive part Area III Area I the composite is nonconductive, the matrix includes the separate particles of conductive filler. Area I Area II Area II the region of percola-tion, the conductive cluster is created, the conductivity sharply increases at ϕ > ϕ c Percolation Threshold Area III the conductivity slowly increases because of growth of conductive cluster. ϕ c Filler volume fraction, ϕ 18

19 Electrical behavior Electrical Conductivity Effect of Ni Effect of Ni distribution -2 Silicone/Ni // Silicone/Ni random -4 Silicone/Ni _I_ log (σ, S/cm) Percolation threshold ϕ c =2vol.%, t=1.07 Percolation threshold ϕ c =25vol.%, t= Ni vol.(%) 19

20 Conclusion Combination of polymers with conductive fillers allows an increasing of both thermal and electrical properties Effect of Ni content on λ, α, cp and σ Effect of Ni distribution (orientation) on λ, α, and σ Use of a magnetic field during the preparation of the composites enhancement of the conductivities (λ, σ) and α 20

21 Thank you 21