Enhancement of Mechanical and Thermal Properties in Boron-Modified Urea-Formaldehyde Fibers

In this study, boron was added to urea-formaldehyde resin’s structure, dry spinning and heat curing were then used to create boron-modified urea-formaldehyde fiber (BUFF). Which improved the fracture strength and toughness of urea-formaldehyde fibers. The chemical and morphological characteristics of the resultant fiber samples were investigated utilizing Fourier transform infrared spectroscopy (FTIR) and 13C nuclear magnetic resonance analysis (13C NMR). The thermal stability properties of various fibers were examined through thermogravimetric analysis (TGA), while their tensile strength was assessed using a tensile tester. The results demonstrated that boron was incorporated into the urea-formaldehyde molecules via B‒O bonds, which subsequently enhanced the three-dimensional network cross-linking within the fibers. This incorporation significantly improved the mechanical properties of the urea-formaldehyde fibers. The breaking strength of urea-formaldehyde fibers, thermally cured at 180°C for 20 min with the addition of 4% boric acid, was determined to be 481 MPa, reflecting a 138% enhancement over the original strength. The elongation at break was measured at 7.0%, indicating a 94% improvement from the initial value. Moreover, the thermal properties of the fibers were significantly improved, evidenced by a 20°C increase in the onset decomposition temperature and a residual carbon content of 28.47%.