Plasma Surface TreatmentOverview
Feasibility Demonstrated, some engineering remains before scaling.Advantages
Enhanced bonding to existing resins and sizings Higher performing parts with same CF content Lower CF content per part for same mech. performance Bond to new resin systems More environmentally friendly than wet chemical methods. Lower the cost of composites
Compatible with all precursors.
Plasma Surface Treatment – Distinct Advantages
Pre-treatment Oxidation Carbonization Surface treatment Sizing Spooling
Typical PAN-Based Carbon Fiber Conversion
A Comparison of Surface Treatment MethodsIndustrial Practice
Gaseous Surface Treatment
Key factors Influencing the Fiber/Resin Bond
•Compressive stress at the interface due to the cure volume shrinkage of the matrix: control of the cure of the matrix at the interface and creation of a buffer zone to limit that inherent effect.
Vinyl ester monomerCarbon fiber
Covalent bonding, functional group reactive with –OH and COOH.
Covalent bonding, functional group reactive with C=C
• Mechanical interlocking: increase of the surface area of the fiber (increase of the roughness of the surface) by thermochemical surface treatment•Presence of defect: removal of the weakly boundary layers located at the surface of the fibers by thermochemical surface treatment•Physical interactions (polar, dispersive): increase of the surface energy of the fiber and its polar component due to the creation of oxycarbonated functionalities (-OH, -COOH mainly) by thermochemical surface treatment, better wetting.•Chemical interactions: creation of covalent bond by the grafting of coupling agents
Gas Phase Surface Treatment – Two Methods
Triples the oxygen concentration on the carbon fiber surface as compared to Electrochemical industrial practice
Conventional Thermochemical PlasmaSurface Treatment Method
Plasma Surface Treatment – Chemical Flexibility
LAB SCALE DEVICE
ONHNH2Amine Imine Carbonyl
Polyurethanes, nylons, polyesters
Plasma Surface TreatmentScale-Up Conceptual Design (~250 MT-CF/yr.)