Growing Nano-SiO2 on the Surface of Aramid Fibers Assisted by Supercritical CO2 to Enhance the Thermal Stability, Interfacial Shear Strength, and UV Resistance

Abstract

Aramid fibers (AFs) with their high Young′s modulus and tenacity are easy to degrade seriously with ultraviolet (UV) radiation that leads to reduction in their performance, causing premature failure and limiting their outdoor end use. Herein, we report a method to synthesize nano-SiO2 on AFs surfaces in supercritical carbon dioxide (Sc-CO2) to simultaneously improve their UV resistance, thermal stability, and interfacial shear strength (IFSS). The effects of different pressures (10, 12, 14, 16 MPa) on the growth of nanoparticles were investigated. The untreated and modified fibers were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). It was found that the nano-SiO2-decorated fibers exhibited improvement of thermal stability and mechanical properties, and the IFSS of the nano-SiO2 modified fibers increases by up to 64% compared with the untreated fibers. After exposure to 216 h of UV radiation, the AFs-UV shows a less decrease in tensile strength, elongation to break and tensile modulus, retaining only 73%, 91%, and 85% of the pristine AFs, respectively, while those of AFs-SiO2-14MPa-UV retain 91.5%, 98%, and 95.5%. In short, this study presents a green method for growing nano-SiO2 on the surface of AFs by Sc-CO2 to enhance the thermal stability, IFSS, and UV resistance.

Recent advancement in surface modification of aramid fiber assisted by supercritical carbon dioxide

“…It was found that the SiO 2 nanoparticles were decorated on AF and demonstrated upgrading of structural characteristics and thermic coherence, and the IFSS of the modified AF‐nano‐SiO 2 rises to 64% evaluated with the pristine fibers. Afterward, experiencing ~215 h UV radiation, the UV modified aramid fibers exhibits a lower diminution in elastic modulus, tensile strength, and breaking strain retentive only 72%, 90%, and 86% of the untreated aramid fibers, individually, while those of UV treated and SiO 2 incorporated aramid fibers at 14 MPa hold 91%, 97%, and 95.5% 64 . Ding et al 65 carried out an experiment to coat the SiO 2 nano‐sized particles on the AF skin layer with an optimum concentration of 0.15 mol/L.…”

“…Afterward, experiencing $215 h UV radiation, the UV modified aramid fibers exhibits a lower diminution in elastic modulus, tensile strength, and breaking strain retentive only 72%, 90%, and 86% of the untreated aramid fibers, individually, while those of UV treated and SiO 2 incorporated aramid fibers at 14 MPa hold 91%, 97%, and 95.5%. 64 Ding et al 65 Under the effect of forming uneven, intermolecular force, large particles lead to shedding on the surface of the fiber. 66,68 Enhancement of ILSS characteristics essentially relies on these nanoparticles' quantity, orientation, and dispersion.…”

Facile flame-retardant finishing for cotton in supercritical CO2

“…In addition, SiO 2 particle size gradually increases with an increase in time due to the aggregation. 24 At the moment, more flame-retardant molecules adhere to the surface rather than diffusing into cotton fiber. Under the weak physical adsorption, flame-retardant aggregates detach more easily from the fibers, and SiO 2 particles continue to absorb and diffuse into cotton as CO 2 circulates, thereby displaying a decreased trend followed by an increased trend from 90 to 120 min.…”

High Interfacial Shear Strength and High Tensile Strength in Heterocyclic Aramid Fibers with Improved Interchain Interaction

“…Focusing on structural optimization to improve the IFSS of HAFs, a lot of methods referring to the cross-linking of polymer chains and surface modification of aramid fibers have been developed. [35][36][37][38][39][40][41][42][43][44][45] Surface modification usually includes physical and chemical approaches, such as high-energy radiation treatment, [36][37][38] surface coating, [39][40] chemical grafting, [41][42][43][44] and acid-base corrosion. [45] However, these strategies usually have adverse effects on the tensile strength.…”

“…[42] Surface treatment of HAFs by chemical and physical methods, such as chemical grafting, surface coating, plasma irradiation, and so on, can improve surface polarity and roughness to enhance their combination with a matrix. [34,[43][44][45] However, these strategies not only lead to a decrease in tensile strength by destroying the dense structure of fibers, but also require complicated steps. Therefore, it is crucial to develop a simple method to attain both high IFSS and high tensile strength in HAFs.…”