Characterization of structural changes of poly(vinyl methyl ether) gamma-irradiated in diluted aqueous solutions.
An aqueous deoxygenated dilute PVME solution (cP = 0.5 mass %) was irradiated with gamma-rays at different radiation doses (D = 0.2-10 kGy). At these concentrations and doses contracted molecules are formed but no macroscopic networks. For the analysis of the structural changes, the irradiated samples were analyzed by size exclusion chromatography (SEC) with a triple detector system, static light scattering, and viscometry. SEC measurements necessitate for the application of the universal calibration principle the knowledge of the Kuhn-Mark-Houwink (KMH) parameters. To obtain these parameters commercially available poly(vinyl methyl ether) was fractionated and analyzed by the same means. We found at 30 degrees C a KMH relationship to [eta] = 0.0226 (mL/g) x Mw(0.67) in THF. We observed an increase in molar masses without any significant structural changing for D < 0.5 kGy. With increasing radiation dose, the intramolecular cross-linking reaction becomes more and more important. The results of viscosity measurements show a slight increase in contraction for 1.0 kGy. For irradiation dose higher than D > 1.5 kGy, a strong contraction occurs. For D > 5.0 kGy, the favored intramolecular reactions lead to the formation of microgels.
Querner
Claudia
C
Institut für Physikalische Chemie und Elektrochemie, Technische Universität Dresden, D-01062 Dresden, Germany.
Schmidt
Thomas
T
Arndt
Karl-Friedrich
KF
D005720:Gamma Rays; D008738:Methyl Ethers / Q000737:chemistry / Q000528:radiation effects; D011145:Polyvinyls / Q000737:chemistry / Q000528:radiation effects; D012996:Solutions / Q000737:chemistry; D013499:Surface Properties; D014867:Water / Q000737:chemistry
D008738:Methyl Ethers; D011145:Polyvinyls; D012996:Solutions; D014867:Water