Self‐Healing Capabilities in Epoxy UF–DCPD Composites by Investigating Fracture and Scratch Properties

In situ polymerization was used to create self‐healing composites containing UF (urea‐formaldehyde) as shell of microcapsules, DCPD (dicyclopentadiene) as the core material of microcapsules, and epoxy as the matrix material. Ultrasonication was employed to disperse microcapsules in epoxy. Composites with self‐healing capsules at weight percentages of 0.5, 1.0, 1.5, and 2.0 were fabricated. The DCPD‐containing microcapsules were found to be spherical with an average diameter of 159 nm. To investigate the fracture properties of the composites, SENB (single‐edge notched bending) specimens were used to determine the virgin (without microcapsules/plain epoxy) and healed (with microcapsules) fracture toughness properties. Plain epoxy/virgin fracture toughness increased by 81% at 1.5% microcapsule weight. Compared to plain epoxy, the healed (with microcapsules) fracture toughness of composites rose, respectively by 84%, 75%, 82%, and 52% for 0.5, 1, 1.5, and 2 wt% of microcapsules. A scratch resistance test was performed using a non‐contact surface profilometer to examine the healing behavior. It was discovered that the cut's depth decreased for up to 24 h. After a day, the cut's depth had barely decreased. Composites containing 2.0 wt% microcapsules exhibited the highest recovery of 37%.