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

Luwei Zhang,Muhuo Yu,Haijuan Kong,Mengmeng Qiao,Xiaoma Ding

doi:10.3390/polym11091397

Luwei Zhang, Muhuo Yu + Show 3 more

Open Access

https://doi.org/10.3390/polym11091397

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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.

Highlights

Materials with extraordinary mechanical properties are required in industrial fields
Compared with the absorption value of the untreated fiber at 396 nm, the fibers treated under the pressure of 10, 12, and 14 MPa increases by 33%, 41%, and 52%, respectively, suggesting the improved absorption capacity of Aramid fibers (AFs) with the increasing contents of nano-SiO2, which is in good agreement with
These results indicate that nano-SiO2 can reduce the damage of UV irradiation to AFs

Summary

Introduction

Materials with extraordinary mechanical properties are required in industrial fields. The abundant intermolecular hydrogen bonding and high degree of crystallinity lead to a smooth and inert surface of AFs, which hinders the adhesion strength of AFs to epoxy matrices, limiting its application in composite materials [7]. The large amount of amide bonding in fibers is decomposed by UV irradiation [8,9], high temperature [10], and moisture [11]. These drawbacks constrain the working durability of AF-based composites under long-term outdoor conditions [12]

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