Monitoring the aging dynamics of glycidyl azide polyurethane by NMR relaxation times

Citation
M. Laviolette et al., Monitoring the aging dynamics of glycidyl azide polyurethane by NMR relaxation times, MACROMOLEC, 32(5), 1999, pp. 1602-1610
Citations number
81
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
MACROMOLECULES
ISSN journal
00249297 → ACNP
Volume
32
Issue
5
Year of publication
1999
Pages
1602 - 1610
Database
ISI
SICI code
0024-9297(19990309)32:5<1602:MTADOG>2.0.ZU;2-G
Abstract
We have used solid-state NMR to monitor the aging dynamics of a polyurethan e based on glycidyl azide polymer (GAP) used as a binder in solid rocket pr opellants. me have shown by deuterium NMR longitudinal relaxation time (T-1 ) measurements that it is possible to monitor the degradation of the binder as a function of time for samples with different NCO/OH ratios. The longit udinal relaxation was found to be nonexponential. Thus, we have used a stre tched exponential equation of the type Kohlrausch-Williams-Watts to determi ne the value of T-1ww. With the help of the gamma function, the average val ue of T-1 ([T-1]) was determined without knowing the shape of its distribut ion function. Since the solid-state NMR method has the advantage of being n ondestructive, we were able to monitor the aging of the polyurethane sample s that; were kept in ambient conditions rather than in the extreme thermal conditions usually applied in aging studies of polymers.