Carbon fibre surface modification facilitated by silver-catalysed radical decarboxylation

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Carbon fibers are crucial reinforcing agents in composite materials.
• Improving the interface between carbon fibers and polymer matrices is key to enhancing composite performance.
• Surface modification of carbon fibers can enhance their compatibility and bonding with matrices.

Purpose of the Study:

• To graft a methylacrylate/acrylic acid copolymer onto short carbon fibers using a novel surface modification technique.
• To characterize the surface-grafted carbon fibers.
• To investigate the effect of these modified fibers on the mechanical properties and failure mechanisms of epoxy resin composites.

Main Methods:

• Silver-catalyzed radical decarboxylation for copolymer grafting.
• X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), and Thermogravimetric Analysis (TGA) for surface characterization.
• Fabrication and mechanical testing of epoxy resin composites incorporating modified carbon fibers.

Main Results:

• Successful grafting of a 4:1 methylacrylate/acrylic acid copolymer onto short carbon fibers confirmed by XPS, SEM, and TGA.
• The grafted polymer constituted approximately 10% of the modified fiber mass.
• Epoxy composites with modified fibers showed increased ductility and a transition in failure mode from adhesive (at the fiber-matrix interface) to cohesive (within the matrix).

Conclusions:

• Silver-catalyzed grafting is an effective method for modifying carbon fiber surfaces.
• Surface-grafted copolymers enhance the interfacial properties of carbon fiber reinforced epoxy composites.
• The improved interfacial adhesion leads to enhanced ductility and a more favorable cohesive failure mode in the composites.