ISSN:
0021-8995
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Maschinenbau
,
Physik
Notizen:
Ultracentrifugal techniques have been employed to investigate the degradation of hydroxypropyl guar (HPG) solutions, and of gels formed with a delayed zirconium cross-linker, by ammonium persulphate at 90°C. Molecular weights, M, for various samples of degraded polymer were determined by sedimentation/diffusion, and an empirical relationship was established between M and the sedimentation coefficient at a single, low concentration. This enabled the straightforward determination of M as functions of persulphate concentration, cross-linker concentration, and time at temperature. It was shown that large decreases in M occur within the first hour at temperature, but that complete degradation is not achieved. It was further shown that, when a delayed zirconium cross-linker is used, degradation may be less effective when gels are formed and degraded at high shear rates.
Zusätzliches Material:
4 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/app.1991.070420808
Permalink
