Polyfvinyl fluoride

Conformational energy estimates are employed to determine the conformational characteristics of polyfvinyl fluoride) (PVF), polyfluoromethylene (PFM), and polytrifluoroethylene (PTF3). Effects of stereoconfiguration and, in the case of PVF and PTF3, the presence of head-to-head tail-to-tail (HH TT) defect structures are considered. The calculated results are compared to corresponding values found for polyfvinylidene fluoride), polytetrafluoroethylene, and polyethylene, and the equilibrium flexibilities of PVF, PFM, and PTF3 are discussed on this basis. 

Propylene carbonate [ 108-32-7] is liquid at room temperature. It is a high boiler with a solvency resembling that of ethylene carbonate. It dissolves polyacrylonitrile only in combination with ethylene carbonate. Propylene carbonate is used in paints as a high-boiling solvent and film-forming auxiliary, especially in polyfvinyl fluoride) and poly(vinylidene fluoride) systems. It is also employed as an auxiliary in the pigment and dye industry. 

The crystal in Fig. 5.34 illustrates the concept of isomorphism, the possibility that two different motifs fit into the same crystal. For polymers isomorphism of repeating units is most important. Isomorphism of complete chains is seldom possible. Polyfvinyl fluoride) that fits into a crystal of poly(vinylidene fluoride) provides a rare exception. The repeating-unit isomorphism can be separated into three types Type 1 occurs when both homopolymers have die same crystal structure, and a smooth change of the lattice parameters occurs on changing the concentration. An example of type 1 repeating-unit isomorphism is poly(vinylidene fluoride-co-vinyl fluoride). Type 2 is also called isodimorphism and occurs if the homopolymers have different crystal structures. A change in structure occurs at an intermediate concentration. Type 3 occurs if one homopolymer does not crystallize by itself, but participates in the crystal of the other. 

Table 7. Melting Point and Degree of Crystallinity of Polyfvinyl fluoride) Obtained at Various Polymerization Temperatures, ...

PCTA poly(cyclohexylene dimethylene terephthalate) PVE polyfvinyl fluoride)... 

A. E Tbnelli, Coofonnational characteristici of polyfvinyl fluoride). potyffluaraasethyleneX and poly(trifiuoroetkyleneX MacnmolectUes 75 734 (1980). 

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