THE EFFECTS OF UV EXPOSURE ON THE STRUCTURAL AND MECHANICAL PROPERTIES OF BNNSS THIN FILMS

Abstract

Boron nitride nanosheets (BNNSs) are good candidate for UV protection. They have ability to absorb the harmful UV part of sunlight and prevent the coated substrate against the environmental degradations. There are several studies focused on boron nitride coatings on copper, steel or etc. for UV protection. However, studies on boron nitride coating on the glass surface are scarce and the behavior of nanostructured thin BNNSs films and long-term effects of UV-radiation exposure have not been studied yet. In this study, we report the effect of UV radiation on the structural, physical and mechanical properties of BNNSs thin films. Boron nitride nanosheets were obtained using isopropyl alcohol (IPA) as solvent with liquid exfoliation method. BNNSs thin films were produced using different immersion numbers at a dipping rate of 3 mm/s (5, 10, 20, 30, 50). Obtained thin films were evaluated for the UV protection ability after 15 and 25 hours as exposure time. Scanning electron microscopy (SEM), UV-visible spectroscopy, was carried out to study the structure and optical properties of the BNNSs films as a function of the UV-irradiation time and immersion number. Mechanical properties of thin films were obtained using 3-point bending test. Atomic Force Microscopy (AFM) was conducted to determine the thickness of nanosheets. It was observed that the thickness of nanosheets is generally changed between 1-4 nm. As the number of immersions increased, the transmittance of the glass surfaces decreased