Supervisor : Dr. Fabian Rios Presented by : Arik Noyman Lorin Bacal July 2009

1. Department of Plastic EngineeringInjection molding of electrically conductive composites based on carbon nanotubesand carbon black Supervisor : Dr. Fabian Rios Presented by : ArikNoyman LorinBacalJuly 2009

2. Objectives • Understanding of polymers electrical properties. • Investigation of PC and PBT composites containing CB and CNT separately. • Investigation of synergistic PC and PBT composites containing CB and CNT together. • Creating composites combining CNT and CB in order to reduce the price and achieve better properties

3. Motivation • Electronic components may damage from ESD during manufacturing, assembly, storage and shipping. • There is a growing demand for conductive plastics. • Plastic composites have advantageous price\weight\performance and easy processed. • Composites containing both CB and CNT may present a synergistic effect in terms of price and properties

4. Introduction • Most polymers are electrically insulating materials. • Conductive Polymeric materials are usually polymer composites containing electrically conductive fillers. • The type of filler used, its electrical conductivity and physical properties have a significant effect on the electrical conductivity of the composite.

5. Conductive mechanism CB CNT Electric conductivity occur when ”free electrons” move easily from atom to atom under an applied electric field.

6. Applications • Antistatic media (ESD elimination) . • Battery and fuel cell electrodes. • Corrosion-resistant conductive materials.

7. Experimental - Materials • PC Carbotex K-20 (Kotec) • PBT Ramster PF-100 (polyram) • CNT Nanocyl 7000 (Nanocyl) • CB Vulcan XC72 (Cabot)

8. Experimental - Methodology Stage 1 – Percolation treshold • Preparing the composites using a co-rotating twin screw extruder : CNT composites: 1.5 - 3.5 wt%, with intervals of 0.5 wt% CB composites: 6 - 16 wt%, with intervals of 2 wt% • Injection molding of the composites. • Testing and characterization the injected samples : Electrical Resistivity Tensile Impact Rheology

9. Stage 2 • According to the percolation threshold (P.T.) found in stage 1, CB and CNT containing composites were prepared:

10. Results And Discussion [stage 1] Electrical Properties CNT composites Percolation Threshold of CNT: 3 wt% for PBT 3.5 wt% for PC

11. Results And Discussion – Electrical properties CB composites Percolation Threshold of CB: 14 wt% for both materials

12. Results And Discussion – Mechanical Properties composite * The table represent the conducting composites compared to the neat matrix

13. Stage 2 - composite containing CNT and CBTEM image of a conductive composite containing CNT and CB CB CNT CARBON NANOTUBES: A HIGH PERFORMANCE CONDUCTIVE ADDITIVE [26]

14. Results And Discussion [stage 2] Electrical Properties

15. Results And Discussion – Economic Rentability * CNT cost – 50 [$\Kg] * CB cost – 5 [$\Kg]

16. Results And Discussion – PC composites properties

17. Results And Discussion – PBT composites properties

18. Results And Discussion - Rheological behavior

19. Results And Discussion - Rheological behavior

20. Results And Discussion – PC Properties Comparison Best composite Worst composite

21. Results And Discussion – PBT Properties Comparison Best composite Worst composite

22. Conclusions Electrical Resistivity • Addition of CNT and CB separately into PC and PBT creates conductive composites. • PC demonstrated higher percolation threshold than PBT. • Addition of both CNT's and CB into the same polymeric matrix increases the electrical conductivity, positive synergy was achieved.

23. Conclusions - Mechanical Properties • The filler leads to higher stiffness of the composites: an increase in the Young's modulus and a decrease in elongation. • CNT's reinforce the composites more efficiently than CB. • Positive synergy of the mixed additive composites can be easily achieved using standard processing parameters.

24. Conclusions - Rheological Characterization • CNT has greater effect on the viscosity than CB. • The electrically conductive composites had showed a shear-thinning behavior. • PC mixed-additive composites behavior resembles the PC\CNT behavior. • PBT mixed-additive composites viscosity had decreased compared to the PBT\CNT

25. Conclusions - General • Reducing the CNT content in CNT-based composites and incorporating CB into the same matrix decreases the electrical resistivity by a synergistic effect along with an improvement of mechanical properties compared to the single additive composites. • The composite that demonstrated the best properties combination were: PBT-1.3CNT-7CB, PBT-1.3CNT-11CB PC-1CNT-11CB and PC-2CNT-7CB.

26. Further work • Composites that are recommended to perform DOE on are: PBT-0.7CNT-11CB, PBT-1.3CNT-7CB, PBT-1.3CNT-11CB PC-1CNT-11CB and PC-2CNT-7CB • A dispersion agent should be used in CB compounding. • Surface treatment for the CNT. • A TEM investigation should be done in order to understand the morphological structure of the composites. • Finding a compitabilizer that improves the deformation ability is highly desirable.

27. Acknowledgments • Dr. Fabian Rios • Rachel Lipman • ShuraMuchlove • Yossi Hazut • Irena Belinski • Moshe Rubino • Roni Efrati

28. Thank You

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