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Curing of a polysulfide sealant with sodium birnessite
Author(s) -
Donaldson J. D.,
Grimes S. M.,
Houlson A. D.,
Behn S.
Publication year - 2000
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/1097-4628(20000808)77:6<1177::aid-app2>3.0.co;2-s
Subject(s) - birnessite , polysulfide , curing (chemistry) , ultimate tensile strength , manganese , vulcanization , materials science , chemistry , sodium , chemical engineering , polymer chemistry , composite material , manganese oxide , natural rubber , metallurgy , electrode , electrolyte , engineering
Sodium birnessite (Na 2 Mn II 2 Mn IV 5 O 13 · H 2 O), a layered manganese(IV) oxide–based phase, gives a liquid polysulfide cure that is too rapid for normal application when added at 10 pph polysulfide. The curing behavior of sodium birnessite added as 5 pph, 4 pph, and as a 5 : 5 pph mixture with an inert natural manganese dioxide was compared with that of a readily available manganese‐based commercial curing agent. The rate of cure at 5 and 4 pph was slower than the commercial agent at 10 pph and led to products with lower tensile strength. The cure with the 5 : 5 pph mixture gave a more rapid reproducible cure than that of the commercial agent, making a product with a higher tensile strength and lower elongation, which indicates better curing and higher crosslinking. The improved performance of sodium birnessite as a curing agent is consistent with the presence of Mn 2+ in the lattice, creating vacancies in the Mn 4+ O 2− lattice and increasing the mobility of Mn 4+ and its transport to the surface of the solid to oxidize the polysulfide. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1177–1181, 2000