02 CFRC
The properties of carbon fiber composites are determined by three main components: fiber, matrix and interface layer.
INTERFACR: Interface is an intermediate phase between the reinforcing phase and the matrix phase, which is the bridge between the reinforcing phase and the matrix, as well as the transmitter of stress and other information.
D400,as a traditional cross-linker of epoxy,
contains two active primary amine groups located on secondary carbon atoms at each end of an aliphatic polyether chain . And flexible polyether chain contributes to stress transfer between carbon fiber and epoxy.
02 CFRC
What is Carbon fiber reinforced composites ?
CFRC is a kind of structural material made of carbon fiber with resin, metal or ceramics.
Excellent tensile strength, high stiffness, light weight and great thermal resistance make carbon fiber reinforced composites an ideal structural material.
RESEARCH AND TREATMENT OF THE SURFACE OF CARBON FIBER IN CARBON FIBER REINFORCED COMPOSITES
contents
PART 01 PART 02 PART 03 PART 04
Introduction CF interface
①the impurities attached to the mold release agent; ②the aging of the interface layer formed when the oxide layer,hydrate layer; ③the substrate is not fully infiltrated and bound by the air layer; …….
Electro polymerization
Whisker growth method
Plasma method
03
PART THREE
Article one
01 GRAFTING
Grafting of micro-molecules or polymers onto the carbon fiber surface can yield a controlled, ordered and active structure, which has can be an effective modification method.
ACF/D400 enforced epoxy composites
03 RESULTS AND DISCUSSION
The following depicts the surface morphologies and roughness of the carbon fibers.
03 RESULTS AND DISCUSSION
IFSS was adopted to quantify the interfacial property between carbon fiber and epoxy.
F----maximum load recorded d----carbon fiber diameter l------embedded length
02
PART TWO
CF interface
01 INTERFACE
The property of CF composites mainly depends on the quality of the interface between the matrix and the reinforcement, which determined the way of the loads transfer from the matrix to the carbon fiber. The improvement of the interfacial adhesion strength between the carbon fiber and polymer matrix is a key factor to improve mechanics performance of composite materials.
03 METHODS TO ENHANCE THE ADHESION
Second, the surface morphology is suitable for bonding.
The increase of surface roughness is beneficial to the mechanical fitting of carbon fiber and matrix resin, and to enhance the effect of anchoring.
02 PROCESSES
CF
HNO3（80℃、4h） washed several times， dried under vacuum
重复性
增强因子
ACF
D400（90℃、4h） HATU was used as condensing agent
Washed dried in a vacuum furnace
Third, improve the affinity of resin and reinforcement.
The introduction of polar or reactive functional groups, and the role of the intermediate layer with resin, such as - COOH, - NH2, - OH.
After adsorption of D400, the IFSS of CF/D400 composite increases to 55.8 MPa which is attributed to improvement of surface energy.
D400,which can not only react with the reactive groups on the carbon fiber surface, but also increase resin compatibility and react with the matrix system. D400 molecules have exactly and completely covered the whole surface of carbon fibers at 2 *10-4 mol/L concentration.
03 RESULTS AND DISCUSSION
The following depicts the surface morphology of carbon fibers after debonding from the epoxy matrix Before grafting（Fig a）,the debonding between carbon fiber and epoxy is interfacial failure. After adsorbed D400, more epoxy debris adhere on the carbon fiber after debonding , due to the strong covalent bonds formed between amino and carboxyl groups. As D400 concentration goes up, there is more remaining epoxy resin.
03 METHODS TO ENHANCE THE ADHESION
Vapor phase oxidation
oxidation
Liquid phase oxidation
Catalytic oxidation
surface treatment
Non-oxidation
Vapor deposition method
Composite interface phase
03 METHODS TO ENHANCE THE ADHESION
How to increase the adhesion between CF and resin? First, prevent the formation of weak interface layer.
03 RESULTS AND DISCUSSION
The wettability of carbon fiber is investigated using advancing dynamic contact angle test.
After D400 grafting treatment, the contact angles decrease, while the surface energy of carbon fiber increases. The wettability of carbon fiber was increased and the change of the fiber surface free energy confirms the successful deposition of D400 on carbon fiber surface.