INVESTIGADORES
RIVERO guadalupe
artículos
Título:
Resol/Montmorillonite Nanocomposites obtained by in-situ polimerization
Autor/es:
RIVERO, GUADALUPE; VAZQUEZ ANALÍA; MANFREDI LILIANA
Revista:
JOURNAL OF APPLIED POLYMER SCIENCE
Editorial:
Wiley
Referencias:
Lugar: New York; Año: 2009 vol. 114 p. 32 - 39
ISSN:
0021-8995
Resumen:
Nanocomposites based on resol resin and layered silicates were obtained by in-situ
polymerization. An increment in the viscosity and in the content of free formaldehyde in
the prepolymer with the addition of clay was observed. It could be attributed to the entrance
of small phenol molecules into the galleries modifying the concentration of reagent enabled
to react outside the clay galleries.
The composites were cured by temperature and it was observed that the type of clay affect
their dispersion in the polymer. The unmodified Cloisite® Na+ montmorillonite (CNa) was
the best dispersed in the polymeric matrix while the modified montmorillonites (MMTs)
showed an interlayer contraction after curing. It seems to be due to the loss of modifiers
from the clay or to the different rate of curing inside and outside the galleries. In addition,
the composite containing CNa presented higher crosslinking density than the others with
modified MMTs. More adhesive strength was observed in that composite as well. It was
related with the void content and the polarity of the samples. These results were compared
with the ones obtained when the nanocomposites were synthesized by mixing the clay with
the prepolymer. The nanocomposites with the addition of CNa showed similar properties
independent of the way of synthesis used. However, it seems that the modified clays are
better dispersed by mixing with the prepolymer than by in-situ polymerization. Na+ montmorillonite (CNa) was
the best dispersed in the polymeric matrix while the modified montmorillonites (MMTs)
showed an interlayer contraction after curing. It seems to be due to the loss of modifiers
from the clay or to the different rate of curing inside and outside the galleries. In addition,
the composite containing CNa presented higher crosslinking density than the others with
modified MMTs. More adhesive strength was observed in that composite as well. It was
related with the void content and the polarity of the samples. These results were compared
with the ones obtained when the nanocomposites were synthesized by mixing the clay with
the prepolymer. The nanocomposites with the addition of CNa showed similar properties
independent of the way of synthesis used. However, it seems that the modified clays are
better dispersed by mixing with the prepolymer than by in-situ polymerization.