ISSN:
0021-8995
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Maschinenbau
,
Physik
Notizen:
Mechanical scission of two typical perfluoropolyethers was investigated: Y, a copolymer of —CF(CF3)CF2O—, —CF2O—, and —CF(CF3)O—, and Z, a copolymer of —(CF2)nO—, with n = 1,2,3,4. Undiluted polymers were subjected to prolonged shearing in a media mill with ZrO2 particles. A chemical extraction of the polar ZrO2 particles was carried out to collect adsorbed polar scission products. Mechanochemical scission products from both the Y and Z fluorocarbon polymers were identified by 19F-NMR. A significant amount of CF3CO2- was present after the milling and the primary functional groups formed at scissioned chain ends were —CO-2. A hydrodynamic expression was derived and the maximum extension rate was estimated to be in the range of 5 × 106 s-1. 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. © 1993 John Wiley & Sons, Inc.
Zusätzliches Material:
9 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/app.1993.070500807
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