Mechanical scission of perfluoropolyethers

✍ Scribed by T. E. Karis; V. J. Novotny; R. D. Johnson

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 843 KB
• Volume: 50
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1993.070500807

✦ Synopsis

Mechanical scission of two typical perfluoropolyethers was investigated Y, a copolymer of -CF(CF3)CF20-, -CF20--, and -CF(CF3)O-, and Z, a copolymer of -( CF2),0 -, with n = 1,2,3,4. Undiluted polymers were subjected to prolonged shearing in a media mill with ZrOz particles. A chemical extraction of the polar Zr02 particles was carried out to collect adsorbed polar scission products. Mechanochemical scission products from both the Y and Z fluorocarbon polymers were identified by "F-NMR. A significant amount of CF3CO; was present after the milling and the primary functional groups formed at scissioned chain ends were -CO;.

A hydrodynamic expression was derived and the maximum extension rate was estimated to be in the range of 5 X lo6 s-'. Initial degrees of polymerization were between 20 and 200, well below levels for which flow-induced scission is expected to occur. Final degrees of polymerization were less than 10, and the scission was noncentral and nonrandom in both polymers. 0