1. Atmospheric Plasma(AP)Treatment of Carbon Fiber Joseph Heil 7/17/2009

2. Purpose Increase fiber to resin adhesion Maintain strength & stiffness of fiber Stronger or lighter composites Applicability to other fibers 2

3. Intro to Atmospheric Plasma 760 Torr Reduces complexity Ionized gas High energy electrons Low energy ions Low density compared to vacuum plasma 3

4. Fiber to Resin Adhesion Controlled by: Surface chemistry Surface area Mechanical interlocking Current Solutions: Electrochemical oxidation Coupling agents (size) Non-circular fiber cross-section 4

5. What Can AP Do? Deposit polymer coating Functionalize fiber surface Increase surface roughness Potential for significant damage 5

6. Factors Effecting Treatment Gas composition Power Dwell time Chamber Design 6

7. Tensile Testing 7

8. Distribution of Breaking Loads 8

9. ANOVA Table 3. Two factor ANOVA: treatment time and chemistry 9

10. ANOVA Table 4. Adjusted ANOVA to only reflect contribution of plasma chemistry 10

11. SEM Imaging C-AP1 B – RCF4 A-Virgin 11

12. Resin to Fiber Adhesion 12

13. Cornell SEM Analysis B-Ribbed Surface A-Projecting Fibrils C-Detailed Projecting Fibrils D-Detailed Ribbed Surface 13

14. Conclusions Atmospheric Plasma can be used to increase the resin to fiber adhesion of carbon fiber Treatment increases surface area/ mechanical interlocking Gas chemistry more significant than treatment time Non-uniformity in plasma may contribute to reduction in strength of fiber 14

15. Future Work Sized versus unsized fibers Chemical Analysis Chamber design/ discharge method 15

16. Acknowledgments Matthew King Dr. Jerry Cuomo Dr. Anil Netravali 16

17. Questions 17 Joseph Heil jpheil@ncsu.edu

18. X-Ray Photoelectron Spectroscopy 18

19. Introduction to Carbon Fiber Advantages High strength to weight ratio High thermal & electrical conductivity Military, commercial, & consumer applications Disadvantages Cost Complex/ proprietary manufacturing Poor resin to fiber adhesion 19