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Membrane Distillation, Membrane Crystallization, and Membrane Condenser
Published in Anil K. Pabby, S. Ranil Wickramasinghe, Kamalesh K. Sirkar, Ana-Maria Sastre, Hollow Fiber Membrane Contactors, 2020
M. Frappa, F. Macedonio, E. Drioli
Among the hydrophobic materials applied in the fabrication of membranes for membrane contactors, fluoropolymers constitute a unique class of materials with a combination of interesting properties that attracted significant attention from material researchers over the past few decades [38]. Generally, these polymers have high thermal stability, improved chemical resistance, and lower surface tension because of the low polarizability and the strong electronegativity of the fluorine atom, its small van der Waals radius (1.32˚A), and the strong C–F bond (485 kJ mol−1). The important fluoropolymers for membrane operations are poly(vinylidene fluoride) (PVDF), poly(tetrafluoroethylene) (PTFE), poly(ethylene chlorotrifluoroethylene) (ECTFE), poly(chlorotrifluoroethylene) (PCTFE), poly(vinyl fluoride) (PVF), poly(fluorenyl ether), Hyflon® AD, Teflon® AF, and Cytop®.
Polymers utilised in construction
Published in Ash Ahmed, John Sturges, Materials Science in Construction: An Introduction, 2014
This polymer is mainly used in flammability lowering coating applications in both the construction and aeronautical industries. It is commonly applied to coat metal sheeting. PVF is a thermoplastic fluoropolymer with the repeating vinyl fluoride unit; it is structurally very similar to PVC. PVF has low permeability for vapours, burns very slowly and has excellent resistance to weathering and staining. It is also resistant to most chemicals, except ketones and esters. It is available as a film in a variety of colours and formulations for various end uses, and as a resin for specialty coatings.
Free Chain Polymerization (Addition Polymerization)
Published in Charles E. Carraher, Carraher's Polymer Chemistry, 2017
When vinyl fluoride was prepared in about 1900, it was believed to be resistant to typical “vinyl” polymerization. German scientists prepared vinyl fluoride through the reaction of acetylene with hydrogen fluoride in the presence of catalysts in 1933 (Equation 6.52).
FTIR spectrum of vinyl fluoride near 3.6 μm: rovibrational analysis of the ν4+ν7 band and modelling Coriolis resonances in a seven-level polyad
Published in Molecular Physics, 2018
P. Stoppa, A. De Lorenzi, A. Pietropolli Charmet, S. Giorgianni, N. Tasinato, A. Gambi
In past years, the interest in spectroscopic studies of halogenated ethenes has greatly increased partly due to their potential role as air pollutants. Many compounds are reactive substances and the most important atmospheric transformation processes involve photolysis and chemical reactions with ozone, hydroxyl and nitrate radicals [1–3]. In this context, vinyl fluoride (H2C=CHF) is a compound of a certain importance since it is subject to being accidentally released into the atmosphere when employed in industrial productions of synthetic resins such as polyvinyl fluoride and other fluorinated copolymers that are among the most versatile plastics. Besides, vinyl fluoride, like vinyl chloride and vinyl bromide, is mutagenic and clastogenic and potentially a carcinogenic agent for humans [4].