Fluorocarbons description

A brief description of the key plasma diagnostic techniques, which have been especially useful in delineating the gas phase processes in fluorocarbon plasmas, will be given followed by an extensive discussion of plasma etching and polymerization mechanisms. 

Not identifying trademarked fabric treatments/finishes, referring to them rather by generic descriptions. For example, the descriptions of the same treatment may range from "soil repellent finish" to "fluorocarbon" to "a 3M fluorocarbon" to " Scotchgard ."... 

Gierke also considered that these clusters are interconnected by short, narrow channels in the fluorocarbon backbone network. The diameter of these channels is about 1 mm estimated from hydraulic permeability data. He further considered that the Bragg spacing ( 5nm from SAXS data) can represent the distance between clusters. The cluster-network model is a phenomenological description. Recently, Hsu and Gierke " have derived a semi-phenomenological expression to correlate the variation of cluster diameter with water content, equivalent weight, and cation form of the membrane. They have shown that the short channels are thermodynamically stable. 

The adhesive transfer of organic plastics has some special features of it own. Makinson and Tabor [24] observed that polytetrafluoroethylene sliding on glass left transferred material on the counter surface in the form of lumps, ribbons, sheets or very thin films, depending on the rubbing conditions. Pooley and Tabor [25], who studied the transfer process more intensively, also reported the behavior of other polymers such as fluorocarbon copolymers, polyethylene, polypropylene, polystyrene, polymethylmethacrylate and polyvinyl chloride. Descriptions of transfer in relation to wear were reported for PTFE by Tanaka tt ai. [20] and for polyethylene by Miller a.1. [21]... 

General Description Fluorinated ethylene propylene (FEP), a melt-processable fluorocarbon, is a copolymer of tetrafluoroethylene (TFE) and hexafluo-ropropylene. Fluorinated ethylene propylene and TFE yield similar properties, with the exception ofTFE s lowermelt viscosity.fl 1 DuPont s high-performance material Teflon FEP film is a transparent, thermoplastic film.P ... 

The fluorocarbon surface may be made more wettable by exposing it for a brief moment to a hot flame to oxidize the snrface. The most satisfactory surface treatment is achieved by immersing the plastic in a sodium-naphthalene dispersion in tetrahydrofuran. This process is believed to remove fluorine atoms, leaving a carbonized surface that can be wet easily. Fluorocarbon films treated for adhesive bonding are available from most suppliers. A formulation and description of the sodium-naphthalene process may be found in Table 7.10 (p. 7.37). Commercial chemical prodncts for etching fluorocarbons are also listed. 

The term fluorocarbons is defined here as carbon compounds containing fluorine. If they contain only fluorine, they are sometimes referred to as FCs. The compounds may also contain chlorine, bromine, or hydrogen. Other descriptive names include chlorofluorocarbons (CFCs), fluorinated compounds, and halogen-ated hydrocarbons. Hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (FIFOs) are compounds in this family that contains hydrogen. Unless otherwise specified, the term fluorocarbons in this monograph applies to FCs, CFCs, HCFCs, and HFCs. 

The cohesion between the hydrophobic part of the interfacial adsorption layer and the adjacent nonpolar phase can be modeled nsing the cohesion between model hydrophobic snrfaces in the same liqnid. In snch a simnlation, the hydrophobic solid snrfaces represent the hydrophobic tails of the snrfactant molecnles. This approach allows one to overcome the difficnlties associated with the mutual solubility of the components (see Chapter 1). For the solid/liqnid/solid interface, the main parameter characterizing the interactions is the free energy of interaction, F (or Aoj), which can be established experimentally nsing Derjagnin s theorem, that is, p = %RF, where p is the cohesive force in a direct contact between two spherical particles immersed in a liqnid medinm. Snitable model systems include spherical molecularly smooth glass beads with a radius R 1-1.5 mm and hydrophobized surfaces of different natures, namely, HS and HL, immersed into the hydrocarbon and fluorocarbon liquids, HL and FL. Only dispersion forces are present in such systems, which makes the quantitative description of their interaction well defined and not complicated by the presence of various polar components. 

The combination of properties that makes fluorocarbons highly desirable engineering plastics also makes them nearly impossible to heat or solvent weld and very difficult to bond with adhesives without proper surface treatment. The most common surface preparation for fluorocarbons is a sodium naphthalene etch, which is believed to remove fluorine atoms from the surface to provide better wetting properties. A formulation and description of the sodium naphthalene process can be found in another chapter. Commercial chemical products for etching fluorocarbons are also listed. 

Detailed descriptions of the thermodynamics of phase equilibrium can be found in a number of standard texts [4], In principle, equations of state can be used for the calculation of both liquid- and gas-phase properties, but in practice they have found application only in systems comprising nonpolar, nonassociating compounds of low molecular weight such as hydrocarbons and fluorocarbons. For... 

Bicontimous network of ionic clusters Elliott and co-workers demonstrated a unified morphological description of PFSAs based on both statistical (MaxEnt) and thermodynamic (DPD) descriptions, which broadly favours a bicontinuous network of ionic clusters embedded in a matrix of fluorocarbon chains. Elliott, 201 The existence of a continuous network of water-filled channels explains the high water diffusion coefficient of water in Nafion. 

---