Characteristics of fluoropolymers

It is obvious that the special characteristic of fluoropolymers for NMR is the incorporation of the F nucleus, which is in many ways particularly suitable for study and can act as a unique probe to examine the chemical microstructure, domain structure and mobility at the molecular level for these materials. However, some special techniques are frequently required for the best results from F NMR of solid polymers. These are fully described in Section 6.6. The net result of the difficulties encountered in obtaining high-resolution solid-state F spectra is that relatively few research papers to date have reported spectra with optimised resolution. Therefore, most reported F... 

In the present study, we investigated outgassing characteristics of fluoropolymers for semiconductor industry on exposure to 157 nm, and also investigated outgassing characteristics of PTFE on exposure to focused ion beam (FIB). Outgassed species from these fluoropolymer were detedted by in-situ quadrupole mass spectrometry. 

PVDF exhibits the excellent resistance to harsh environments, characteristic of fluoropolymers. It is widely used in the chemical processing industry, in piping systems, vales, tanks (both molded and lined), and other areas where its combination of excellent mechanical properties and superb resistance to most chemicals make it an ideal material for fluid handling equipment. Increasingly important is use of PVDF as the base resin for long-life, exterior coatings on aluminum, steel, masonry, wood, and plastics. 

Fagan, J.P. and Wadsworth, L.C. (1991) Meltblowing Process and Characteristics of Fluoropolymers, Textiles and Nonwoven Development Center, University of Tennessee, February 1991. 

Arkles B, Gerakaris S, Goodhue R. Wear characteristics of fluoropolymer composites. In Lee LH, editor. Advances in polymer friction and wear (5B). New York Plenum Publishing 1974. p. 663-8. 

The characteristics of fluoropolymers are summarized in Table 1. Thermal and chemical resistance is in general with most of plastics, elastomers and perfluorinated membranes. Weather resistance with the outdoor durability for more than 20 years is specific for fluorinated paint resins. Surface properties such as water and oil repellency are provided by acrylic polymer-based textile finishes and coatings with long-chain per-fluoroalkyl groups. Electrical properties as well as a low refractive index are important for optoelectronics applications like optical fibers. 

Electromagnetic flow meters ate avadable with various liner and electrode materials. Liner and electrode selection is governed by the corrosion characteristics of the Hquid. Eor corrosive chemicals, fluoropolymer or ceramic liners and noble metal electrodes are commonly used polyurethane or mbber and stainless steel electrodes are often used for abrasive slurries. Some fluids tend to form an insulating coating on the electrodes introducing errors or loss of signal. To overcome this problem, specially shaped electrodes are avadable that extend into the flow stream and tend to self-clean. In another approach, the electrodes are periodically vibrated at ultrasonic frequencies. 

The great value of the unique characteristics of fluorinated polymers in the development of modern industries has ensured an increasing technological interest since the discovery of the first fluoropolymer, poly(chlorotrifluoro-ethylene) in 1934. Hence, their fields of applications are numerous paints and coatings [10] (for metals [11], wood and leather [12], stone and optical fibers [13, 14]), textile finishings [15], novel elastomers [5, 6, 8], high performance resins, membranes [16, 17], functional materials (for photoresists and optical fibers), biomaterials [18], and thermostable polymers for aerospace. 

Besides the use in F2 and F2 immersion lithography, fluoropolymers are used in various fields. Fluoropolymer is one of the candidate for a polymer for MEMS, and fabrication of fluoropolymers by ultra-short pulsed lasers (9), and synchrotron radiations (10) has been studied. Polymer outgassing as well as the micro- and nano-fabrication depends on the polymer radiolysis. It is important for the micro- and nano-fabrication to investigate outgassing characteristics which is obvious outcome in the polymer radiolysis. 

On exposure to 157 nm, scission of side chain and C-F bond plays an important roll in outgassing characteristics. Some fluoropolymers for semiconductor industry produce harmful outgassed species of HF which... 

Partially fluorinated fluoropol5miers are significantly different from the perfluoropol5miers with respect to properties and processing characteristics. For example, perfluoropolymers are more thermally stable but physically less hard than partially fluorinated polymers. Both classes of fluoropolymers are discussed in Ch. 3. 

One of the attributes of fluoropolymers is the nonstick property of their surface, which is useful for iimumerable applications. This characteristic prevents bonding of these plastics to themselves and many other materials. Many applications require bonding of fluoropolymer parts to themselves or other substrates. There are two types of solutions to the bonding problem of fluoropolymers with and without an adhesive the former is described in this section. 

There are a number of candidate materials models for predicting the behavior of fluoropolymers. Since the models have varying degrees of complexity, computational expense, and difficulty in determining the material parameters, it is a good idea to use the simplest material model that captures the necessary material characteristics for the application and situation at hand. Unfortunately, it is often difficult to determine, in advance, the required conditions needed by the material model. Hence, it is recommended that a more advanced model be used in order to ensure accuracy and reliability of the predicted data. At a later stage, a less advanced model can be attempted if the computational expense is too great. At that time, the accuracy of the different model predictions can also be tested and validated. 

Coating is one of the important uses of fluoropolymers, since it enables them to exhibit their characteristics on the surface of a substrate. Some of the conventional fluoropolymers such as polytetrafluoroethylene [9002-84-0] (PTFE), tetrafluo-roethylene-hexafluoropropylene copolymer [25067-11-2] (FEP), and ethylene-tetrafiuoroethylene copolymer [25038-71-5] (ETFE) have been used as antistick or anticorrosive coatings. Only poly(vinylidene fluoride) [9002-58-1] (PVDF) has so far been used in paints. The major difficulties in employing thermoplastic fluoropolymers in paints and coatings result from their poor solubility in organic solvents and... 

Polyvinylidene fluoride (PVDF) is a homopolymer of 1,1-difluoroethene with alternating CH2 and CF2 groups along the polymer chain. These groups impart a unique polarity that influences its solubility and electrical properties. The polymer has the characteristic stability of fluoropolymers when exposed to aggressive thermal, chemical, and ultraviolet conditions. 

In Nafion, two general types of environments were noted. One near 100 ppm is characteristic of an amorphous fluoropolymer environment and the other was attributed to ionic environments. The line width of xenon in the ionic region was very large indicating a very heterogeneous environment... 

The unique solubility characteristics of CO2 limit the types of polymerization techniques that can be successfully employed. While amorphous fluoropolymers may be synthesized homogeneously in CO2, most other polymers are insoluble in CO2 and must be made via heterogeneous processes such as precipitation, dispersion, and emulsion techniques or via mass polymerizations swollen by CO2. 

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