Fluorine fundamental properties

This chapter describes the synthesis of partially fluorinated polyimides for optical teleconununications applications," " 2 their optical transparency (optical loss), refractive index, and birefringence properties" in addition to their fundamental properties. It also describes their device application as optical interference filters," " optical waveplates," and optical waveguides." -" ... 

Fundamental Properties of High-Fluorine-Content Polyimide... 

The CSSX process utilizes a novel solvent made up of four components calix[4]arene-bis-(4-fer/-octylbenzo-crown-6) known as BOBCalixC6 as extractant a lipophilic fluorinated alcohol, l-(2,2,3,3-tetrafluoropropoxy)-3-(4-. ec-butylphenoxy)-2-propanol known as Cs-7SB, as diluent modifier tri- -octylamine as a suppressor of impurity effects and the isoparaffinic diluent Isopar L, a mixture of branched hydrocarbons with an average chain-length of 12 carbons. Figure 3 shows the composition of the solvent as currently optimized for the SWPF application at the SRS [37,49], The chemistry of the solvent is well understood, with regards to both its fundamental properties and its performance under process conditions. All of the components are commercially available, and efficient synthetic and purification procedures have been worked out [17,18,37], Thus, these key components may be obtained from multiple chemical suppliers capable of specialty synthesis. 

II. SOME FUNDAMENTAL PROPERTIES OF THE HALOGENS THE ANOMALOUS NATURE OF FLUORINE... 

The size of the fluorine atom allows the formation of a uniform and continuous sheath around the carbon-carbon bonds and protects them from attack, thus imparting chemical resistance and stability to the molecule. The fluorine sheath is also responsible for the low surface energy (18 dynes/cm)[ i and low coefficient of friction (0.05-0.08, static)[ i of PTFE. Another attribute of the imiform fluorine sheath is the electrical inertness (or non-polarity) of the PTFE molecule. Electrical fields impart only slight polarization to this molecule, so volume and surface resistivity are high. Table 1.1 summarizes the fundamental properties of PTFE, which represents the ultimate polymer among all fluoroplastics. 

A fundamental property of fluoropolymers is their resistance to organic and inorganic chemicals (Fig. 12.1). Increased content of fluorine enhances the chemical resistance of the polymer. The overwhelming majority of the applications of fluoropolymers take advantage of their inertness to chemicals. Chemical properties of fluoropolymers are not affected by fabrication conditions. Another aspect of the interaction of these plastics with chemicals is permeation. Even though a reagent may not react with a fluoropolymer, it may be able to permeate through the polymer structure. The extent and rate of permeation is dependent upon the structure and properties of the plastic article as well as the type and concentration of permeant. Temperature and pressure usually influence the permeation process. This chapter reviews chemical compatibility of fluoropolymers and their permeation behavior towards different chemicals. 

Fundamental Properties of Fluorinated Chromia 198 Attempts to Describe Active Sites on Fluorinated Chromia 199 Synthesis of 1,1,1,2-Tetrafluoroethane Over Fluorinated Chromia 200 Oxidation States of Chromium 200 Doped Chromia Catalysts 201... 

In the development of the discussed fluorinated products a lot of fundamental insight has been gained into permeation and adhesion properties of surface-fluorinated polymers. Although this insight is not discussed in this paper, it may be of interest to mention a few significant fundamental discoveries and also to suggest directions for future development. 

Most of the effects induced by the presence of fluorine atoms in a molecule come from both the structure and the fundamental atomic properties of the fluorine atom (Table 1.1). Because of its electronic structure ls 2s 2p, fluorine has very specific properties, as indicated by the extreme values of the atomic parameters given in Table 1.1. ... 

The other major springboard for the fluorocarbon chemical industry was the "Manhattan Project to develop the atomic bomb. This required the large-scale production of highly corrosive elemental fluorine and uranium(VI) fluoride for the separation of the radioactive 235U isotope. Oils capable of resisting these materials were needed to lubricate pumps and compressors, and polymers were needed to provide seals. Peril uorinated alkanes and polymers such as PTFE and poly(chlorotrifluoroethylene) (PCTFE) proved to have the appropriate properties so practical processes had to be developed for production in the quantities required. In 1947 much of this work was declassified and was published in an extensive series of papers3 which described the fundamental chemistry on which the commercial development of various fluoro-organic products, especially fine chemicals, was subsequently based. 

Fluorocarbons are carbon compounds in which hydrogens have been replaced by fluorine atoms. For example the methyl group is CH7 and this would become the trifluoromethyl group CF3. Replacing hydrogens with fluorine has fundamental effects on the properties of a molecule such as making it non-flammable. 

Fluoroolefins are key compounds playing a fundamental role in synthetic fluoroorganic chemistry. Modification of the properties of the double bond by the introduction of fluorine atoms permits the development of reaction routes that are missing in the hydrocarbon series. This creates excellent opportunities for the syntheses of definite structures,... 

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