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Halogen-Based FRs
Published in Asim Kumar Roy Choudhury, Flame Retardants for Textile Materials, 2020
Fluorine plays an important role in flame retardancy. Two important FR fluorine-based FR compounds are polytetrafluoroethylene (PTFE) and fluorinated ethylene propylene (FEP). Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. The well-known brand name of PTFE-based formulas is Teflon (Teflon, 2019).
Experimental Investigation of Condensation and Freezing Phenomenon on Hydrophilic and Hydrophobic Titanium Nanopillared Glass Surfaces
Published in Heat Transfer Engineering, 2021
Mohammad Rejaul Haque, Chen Zhu, Chuang Qu, Edward C. Kinzel, Amy Rachel Betz
MPL followed by liftoff was used to pattern hexagonal close-packed arrays of Ti pillars, as illustrated in Figure 1. The Scanning Electron Microscope (SEM) images of the fabricated surface are shown in Figure 2 (Sample-1: 2 µm periodicity, 200 nm tall, and 800nm diameter; Sample-2: 2 µm periodicity, 200 nm tall, and 781–1006 nm diameter). The fabrication protocol for these samples follows: glass slides, coated with Hexamethyldisilazane (adhesive promoter) were spin-coated with a positive tone photoresist (S1813 Shipley) for 3000 rpm 60 s. The thickness of S1813 was measured to be 1700–1800 nm by ellipsometry. Following a 60 s soft bake at 115 °C, silica microspheres with 2 µm in diameter were self-assembled on the top of the photoresist by drop coating. Then the samples were exposed with 365 nm ultraviolet illuminations. The exposure duration was varied to control the diameter of the exposed features on different samples. On Sample-2, a variable neutral density filter with an optical density range of 0.04–2.0 (Thorlabs), was also used to continuously vary the illumination intensity which corresponds to changing feature size. Following exposure, the samples were immersed into the developer (Microposit MF319) for 60 s. The microspheres were also removed at this stage, leaving photoresist with the HCP hole array. Ti films were e-beam evaporated onto the samples with a thickness of 200 nm or 720 nm. The Ti film was lifted-off by ultrasonicating the samples in RemoverPG (Microchem) to reveal arrays of Ti pillar on the glass. The hydrophobic Ti nanopillared surface was created by spray coating the Teflon© and FC-40 solutions, similar to literature [39]. Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. PTFE is hydrophobic: neither water nor water-containing substances wet PTFE. This research used PTFE as the hydrophobic coating agent. The Teflon© solution was dispersed in FC-40 solvent at a ratio of 1:5. The coating processes involve spray coating of each sample and drying at room conditions. With the passage of time, the Teflon© layer stabilized on the top of the surface. Later, it was baked overnight in an oven at 165 °C to remove all the residual solution.