The spin-spin and spin-lattice relaxation times of protons on polymers, T$ sb{ rm 1p}$ and T$ sb{ rm 2p}$, respectively, have been used to probe the absorbed dose of irradiated polymer solutions in which radiation-induced changes in polymer molecular weight, M$ sb{ rm n}$, occur. The M$ sb{ rm n}$ dependencies of T$ sb{ rm 1p}$ and T$ sb{ rm 2p}$, and of the water proton T$ sb{ rm 1w}$ for solutions of poly(ethylene oxide) (PEO) in D$ sb2$O and H$ sb2$O are presented. T$ sb{ rm 1p}$ and T$ sb{ rm 1w}$ are independent of M$ sb{ rm n},$ and T$ sb{ rm 2p}$ varies with M$ sb{ rm n}$ according to a specific inverse power dependence until low M$ sb{ rm n}$ when T$ sb2$ saturation occurs. The dose dependence of T$ sb{ rm 1p}$ and T$ sb{ rm 2p}$ measured for dilute solutions of PEO in D$ sb2$O reflects the dependence of M$ sb{ rm n}$ on dose. A novel semi-empirical model is proposed for the dose dependence of T$ sb{ rm 2p}$ which incorporates the measured M$ sb{ rm n}$ power dependence of T$ sb{ rm 2p}$ into a theoretical expression of the dose dependence of the M$ sb{ rm n}$. This expression is based on previous bulk polymer work and has been modified to hold for polymers in solution. The model can be fitted well to the T$ sb{ rm 2p}$ data measured for different doses, and the values of the fitting parameters agree with those expected from independent measurements. Practical aspects of the NMR/polymer dosimetry technique are also addressed.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.59996 |
| Date | January 1990 |
| Creators | Audet, Chantal |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Medical Radiation Physics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001217287, proquestno: AAIMM67655, Theses scanned by UMI/ProQuest. |
Page generated in 0.0115 seconds