A facile method to prepare PEG coatings on the fiber surface by the reconstruction of hydrogen bonds for enhancing the interfacial strength of fibers and resins

A new method for functionalizing the surface of aramid fibers by hydrochloric acid is proposed, and new polyethylene glycol (PEG) coatings are prepared on the surface of the fibers by the reconstruction of hydrogen bonds for improving the bond strength with the resins. The structure and morphology of the aramid fibers are characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction instrument, atomic force microscopy, and scanning electron microscopy. Single fiber tensile test and interlaminar shear strength test are carried out to evaluate the mechanical properties of the modified fibers. The results show that the fibers are functionalized after hydrochloric acid treatment. The amino-groups and carbonyl of the aramid fibers are released while both carboxyl and amine groups are produced. In addition, it is also proved that polyethylene glycol has successfully coated the fiber surface, which improves the surface roughness and polarity of the fibers. As a result, the interlaminar shear strength increases by 51.68 %, while the tensile strength of the fibers decreases by 19.61 %.