MODEL MDFS RELATED TO SULFOBELITIC SYSTEMS - STUDIES BY FE-57 MOSSBAUER AND ELECTRICAL-IMPEDANCE TECHNIQUES

New studies of the MDF-processibility of particular components of pote ntial sulfobelitic clinkers in combination with hydroxypropylmethyl ce llulose (hpmc) and/or polyphosphates (poly-P) are presented. The invol vement of Al/Fe, P and C atoms in chemical cross-links within amorphou s AFm -like reaction products in several subsystems of a complex sulfo belitic clinker/polymer system is examined by (i) Fe-57 Mossbauer spec troscopy (to investigate Fe-atom local environments) and (ii) electroc hemical impedance measurements (to characterize conductivity variation s). Fe-III atoms are octahedrally coordinated by oxygens in their firs t coordination sphere, with some replacement of H atoms by C or P atom s in the second coordination sphere, forming cross-links of the type A l/Fe - O - C/P in hydrated products. Impedance spectra were typical of electronically- insulating materials functioning as solid electrolyte s, with conductivity values depending on polymer/gel composition as we ll as on temperature. Copyright (C) 1997 Elsevier Science Ltd.