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preface to fifteenth edition

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POLYMERS, RUBBERS, FATS, OILS, AND WAXES 10.13<br />

above100C, and it is swollen by a number of solvents, especially chlorinated solvents. It is harder<br />

and stronger than perfluorinated polymers, and its impact strength is lower.<br />

10.3.8.6 Ethylene-Chlorotrifluoroethylene Copolymer. Ethylene-chlorotrifluoroethylene copolymer<br />

consists of linear chains in which the predominant 1 : 1 alternating copolymer is<br />

This copolymer has useful properties from cryogenic temperatures <strong>to</strong> 180C. Its dielectric constant<br />

is low and stable over a broad temperature and frequency range.<br />

10.3.8.7 Ethylene-Tetrafluoroethylene Copolymer. Ethylene-tetrafluoroethylene copolymer consists<br />

of linear chains in which the repeating unit is<br />

[9CH 2 9CH 2 9CF 2 9CF 2 9] n<br />

Its properties resemble those of ethylene-chlorotrifluoroethylene copolymer.<br />

10.3.8.8 Poly(vinyl Fluoride). Poly(vinyl fluoride) consists of linear chains in which the repeating<br />

unit is<br />

[9CH 2 9CHF9] n<br />

It is used only as a film, and it has good resistance <strong>to</strong> abrasion and resists staining. It also has<br />

outstanding weathering resistance and maintains useful properties from 100 <strong>to</strong> 150C.<br />

10.3.9 Nitrile Resins<br />

The principal monomer of nitrile resins is acrylonitrile (see “Polyacrylonitrile”), which constitutes<br />

about 70% by weight of the polymer and provides the polymer with good gas barrier and chemical<br />

resistance properties. The remainder of the polymer is 20 <strong>to</strong> 30% methylacrylate (or styrene), with<br />

0 <strong>to</strong> 10% butadiene <strong>to</strong> serve as an impact-modifying termonomer.<br />

10.3.10 Melamine Formaldehyde<br />

The monomer used for preparing melamine formaldehyde is formed as follows:<br />

Hexamethylolmelamine can further condense in the presence of an acid catalyst; ether linkages can<br />

also form (see “Urea Formaldehyde”). A wide variety of resins can be obtained by careful selection<br />

of pH, reaction temperature, reactant ratio, amino monomer, and extent of condensation. Liquid<br />

coating resins are prepared by reacting methanol or butanol with the initial methylolated products.<br />

These can be used <strong>to</strong> produce hard, solvent-resistant coatings by heating with a variety of hydroxy,<br />

carboxyl, and amide functional polymers <strong>to</strong> produce a cross-linked film.

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