Beam Interactions with Materials&Atoms ELSEVIER Nuclear Instruments and Methods in Physics Research B 131 (1997) 295-299 Kinetic study on the radiation-induced polymerization of HDDA and HDDMA E. Takhcs *, L. Wojnhrovits zyxwvutsrqponmlkjihgfedcbaZYXWVUTS Institute of Isotopes of the Hungarian Academy of Sciences, P.O. Box 77, H-1525 Budapest, Hungary zyxwvutsrqponmlkjihgfed Abstract The kinetics of the first steps of electron beam (EB) initiated polymerization in cyclohexane solutions of hexanediol diacrylate (HDDA) and hexanediol dimethacrylate (HDDMA) were investigated by pulse radiolysis with transient spectro- scopic detection. The maxima of the transient UV absorption spectra attributed to a-carboxyalkyl radical in HDDA solution were shifted to longer wavelength by increasing monomer concentration from 1 mmol drne3 to 50 mmol dme3, indicating the onset of oligomer radical formation. In HDDMA solutions the shape of the transient spectra did not change significantly as a result of the lower reactivity of this monomer. The rate parameters of termination (2k,) were determined for both monomers at different concentrations. 6 1997 Elsevier Science B.V. Keywords: Electron beam; Polymerization kinetics; Absorption spectra; HPLC 1. Introduction Acrylates and methacrylates are often used as additives for radiation processing of polymers, mainly for radiation curing of surface coatings and for radia- tion cross-linking. Pulsed laser polymerization (PLP) seems to be an accepted method to determine rate parameters of propagation and termination [l-3]. Pulse radiolysis is a very similar technique for that purpose in the case of high energy radiation initiated polymeriza- tion [4,5]. Electron pulse radiolysis, together with optical detection, is an effective tool to directly observe transient species which can be characterized by their optical absorption or emission spectra and their lifetimes. From the time profiles of the transient ’ Corresponding author. Tel./Fax: +36 1 395 9268, e-mail: takacs@alphaO.iki.kfki.hu. spectra, information can be deduced on the nature of the transients, their participation in a chemical reac- tion and their kinetic characteristics. The rate param- eters of initiation and termination have already been determined for a number of acrylates and methacryl- ates both in cyclohexane solutions [6,7] and in aque- ous solutions [4,8,9]. In this work the early steps of high energy radiation initiated polymerization in cy- clohexane solutions of HDDA and HDDMA are discussed. 2. Experimental Hexanediol diacrylate (HDDA) and hexanediol dimethacrylate (HDDMA) monomers (Scientific Polymer Product) were purified by removing the inhibitor with the chromatographic column supplied. Cyclohexane (J.T. Baker product, spectroscopic 0168.583X/97/$17.00 0 1997 Elsevier Science B.V. All rights reserved. PI1 SO 168- 583X(97)00335- 2 IV. GRAFTING AND POLYMERIZATION