Fluoroplastics sodium etching

Sodium etch Sodium hydroxide Sanitizing melamine or urea polymer, polyolefin, polyethylene oxide, polystyrene, polysulfone, and styrene-acrylonitrile (SAN) Fluoroplastics and some polyesters Polystyrene, polyesters, polyamide, and polysulfone Homopolymer polyacetal Developed by... 

Table 14.2 shows the effect of sodium etching on several fluoroplastics by Tetra-Etch on the surface composition and lap shear bond strength. In general, the data for various fluoroplastics indicate increase in the adhesive bond strength with increasing fluorine and chlorine content. Kinetics of treatment is more favorable to perfluorinated PTFE than PVF that contains one fluorine per monomer unit according to the data in Table 14.2. 

Surface preparation of fluoroplastics can be achieved by a number of methods.h i] The plastic surface can be roughened by blasting with water. Other methods include corona bombardment, cross-linking by activated inert gas species, molten metal alloy treatment, sodium hydride treatment, and sodium etching. The treated layer is at most 1 pm thick and does not alter the bulk properties of the fluoroplastic. Surface... 

Fluoroplastic films such as FEP can be metallized by vacuum deposition. Metal adhesion is enhanced if the surface has been treated for adhesion by sodium etching or other procedures. Untreated general purpose FEP film may be vacuum-metallized for some applications depending upon the specific metal and deposition process. Copper, aluminum, silver, gold, and some metallic oxides have been applied to FEP film by vacuum metallization.f ]... 

Sodium etching is an extreme treatment technique that is suitable for surfaces that are very difficult to treat. Examples include fluoropolymers and thermoplastic polyesters. A description of sodium etching and its application to fluoroplastics is provided in the next section. 

Perfluorinated fluoroplastics are chemically unaffected by nearly all commercial chemicals. An exception is highly oxidizing substances such as element forms of sodium, potassium, and other alkaline metals. This is the basis for sodium etching of fluoroplastic parts, which is described in this section. 

Table 5.23 shows the effect of sodium etching for several fluoroplastics by Tetra-Etch (www.gore. com), on the surface composition and lap-shear... 

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