THE SURFACE MODIFICATION OF SHORT CARBON FIBERS VIA IN-SITU POLYMERIZATION FOR APPLICATION IN FABRICATION OF PHENOL FORMALDEHYDE-BASED COMPOSITES

Abstract

In this research, the short carbon fibers with a length below 100 µm and a diameter of 7 µm were
undergone surface modification through two steps: surface oxidation and followed by in situ polymeization
to form a polymer coating. Then, these fibers were blended with phenol-formaldehyde resin in resol form to
evaluate the mechanical properties of the resulting material. Mechanical properties such as tensile strength,
flexural strength, hardness and impact resistance were determined to compare the properties between
phenol-formaldehyde resin-based composites reinforced with short carbon fibers before and after
modification. The interaction between the resin and short carbon fibers was analyzed by SEM. The results
showed that with a fiber content of 30%, the phenol-formaldehyde resin-based composites reinforced with
short carbon fibers modified by in situ polymeization gave the highest mechanical properties. In particular,
the tensile strength reached up to 108,3 MPa, flexural strength 113,7 MPa, Shore D hardness 91,3 and
impact strength 91,2 J/m2. Morphological analysis showed that at 30% fiber content, modified carbon fibers
were evenly dispersed in the resin matrix, creating good interaction between fibers and resin matrix without
segregation.