The influence of water on the intercalation of epoxy monomers in Na-montmorillonite.
The intercalation of a typical UV-curable epoxy monomer (CE) in unmodified montmorillonite and the effect of hydration on the intercalation reaction are studied. Montmorillonite in the sodium form was submitted to a controlled hydration/dehydration cycle and the water content was checked by TGA/XRD analyses. The structure of the hydrated Na+-montmorillonite was determined from the values of the basal spacings and from the water content of the hydrated form: a coordination of four water molecules per Na ion was found, corresponding to a minimum of energy calculated by molecular dynamics simulation. When dispersing the clay in the CE monomer, the anhydrous Na+-montmorillonite did not show any intercalation; on the contrary the hydrated form showed an increase of the basal spacing. A possible mechanism to explain the intercalation of the CE monomers is proposed.
Bongiovanni
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Dipartimento di Scienza dei Materiali ed Ingegneria Chimica, Politecnico di Torino, C.so Duca degli Abruzzi 24, Torino 10129, Italy. roberta.bongiovanni@polito.it
Mazza
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Ronchetti
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Turcato
E A
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