Molecular Weight Changes Induced in an Anionic Polydimethylsiloxane by Gamma Irradiation in Vacuum

ANGEL J. SATTI; NOEMÍ A. ANDREUCETTI; ANDRÉS E. CIOLINO; CRISTIAN VITALE; CLAUDIA SARMORIA; ENRIQUE M. VALLÉS

RADIATION PHYSICS AND CHEMISTRY (OXFORD)

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: OXFORD; Año: 2010 vol. 79 p. 1137 - 1143

0969-806X

An anionic almost monodisperse linear polydimethylsiloxane (PDMS) wassubjected to gamma irradiation under vacuum at room temperature. The molecular weightchanges induced by the radiation process have been investigated using size exclusionchromatography (SEC) with refraction index (RI) and multi angle laser light scattering(MALLS) detectors, to obtain the number and weight average molecular weights of theirradiated samples.The analysis of the data indicates that crosslinking reactions predominated overscission reactions. The results obtained by SEC-RI have confirmed the presence of smallbut measurable amounts of scission.A previously developed mathematical model of the irradiation process thataccounts for simultaneous scission and crosslinking and allows for both H and Ycrosslinks fitted well the measured molecular weight data. This prediction is inaccordance with the experimental data obtained by 29Si-Nuclear Magnetic Resonancespectroscopy (NMR) and previously reported data for commercial linear PDMS (Satti etal., 2008).