Surface modification of aramid fibers with CaCl2 treatment and secondary functionalization of silane coupling agents

Aramid fibers have excellent mechanical properties as the main reinforcing filler in high-performance composites. However, the adhesion properties between fibers and most polymer matrices were poor. In this study, aramid fiber (AF) was modified by KH550 through surface coating based on the treatment with CaCl₂ solution. The new surface treated with complexing agents could act as an active platform for secondary reactions for further modification. The surface morphology and composition of the treated aramid fibers were tested by scanning electron spectroscopy and X-ray photoelectron spectroscopy, the interlaminar shear strength and the tensile strength of aramid fiber-reinforced polymer (AFRP) of were evaluated. The results showed that the silane coupling agent KH550 was successfully grafted onto the surface of aramid fibers after treatment with CaCl₂. Interlayer shear strength is greatly improved and the tensile strength of AFRP through further grafting with KH550 on the surface treated with CaCl₂ was improved by 48.7%, compared with untreated aramid fiber. In the current scenario, this study is of immense importance because it validates the possibility of secondary modification after fiber complexation modification and useful modification methods, and provides a new direction for the modification of AF.