Organic modification of the clay surface introduces reactive moieties that
disrupt the bundle structure and can potentially make it possible to obtain
individual sheets. Organic modification involves attachment of functional moieties to the open ends and sidewalls of the clay, primarily to improve the solubility
and dispersibility of the clay sheets. Accordingly, one of the best methods of
achieving a homogeneous dispersion of clays in a polymer matrix is the use of
organoclays. This involves organically modifying the clays with polymers that
are structurally similar to the matrix polymer to ensure that the dispersed clays are
compatible with the polymer matrix and to limit any microscopic phase separation in the nanocomposites. Many papers reported large improvements in the
thermal stabilities of TLCP nanocomposites by using organoclay. This enhancement of the thermal stabilities explains reasonably well the dispersed structure of
clay in the nanocomposites caused by the formation of a large aspect ratio of the
clay particles (Chang 2014).
The aim in this chapter was to investigate the effectiveness and influence of two
different processes (melt and solution intercalation) on the morphology and thermal
properties of TLCP/organoclay nanocomposites in order to obtain a material that
combines the excellent thermal behavior provided by addition of inorganic particles
with the versatility and easy processing characteristics of TLCP composites. The general
goal of this work was to use a minimum amount of clay in the hybrids and still obtain
thermal properties significantly superior to those of the matrix polymer. The properties
of these nanocomposites were studied as a function of the organoclay content of the
TLCP matrix.
Experimental
Materials
The source clay, Kunipia-F (Na
+
-MMT), was obtained from Kunimine Co. (Tokyo,
Japan). By screening this Na
+ -MMT clay with a 325-mesh sieve to remove
impurities, we obtained a clay with a cationic exchange capacity of 119 meq/
100 g. Cloisite 25A (organically modified MMT; C25A) was obtained from
Southern Clay Product Co. (Gonzales, LA, USA). All reagents were purchased
from Aldrich Chemical Co. (Yongin, Korea). Commercially available solvents
were purified by distillation.
Syntheses of Organoclays (C12- and C18-MMT)
A dispersion of Na
+
-MMT was added to solutions of the ammonium salts of
dodecylamine (C12) and octadecylamine (C18). These organophilic MMTs were
obtained through a multi-step route (Park and Chang 2000) and have been termed
C12-MMT and C18-MMT, respectively.
21 Characterizations of Nanocomposites of Liquid Crystalline Polymers
581
disrupt the bundle structure and can potentially make it possible to obtain
individual sheets. Organic modification involves attachment of functional moieties to the open ends and sidewalls of the clay, primarily to improve the solubility
and dispersibility of the clay sheets. Accordingly, one of the best methods of
achieving a homogeneous dispersion of clays in a polymer matrix is the use of
organoclays. This involves organically modifying the clays with polymers that
are structurally similar to the matrix polymer to ensure that the dispersed clays are
compatible with the polymer matrix and to limit any microscopic phase separation in the nanocomposites. Many papers reported large improvements in the
thermal stabilities of TLCP nanocomposites by using organoclay. This enhancement of the thermal stabilities explains reasonably well the dispersed structure of
clay in the nanocomposites caused by the formation of a large aspect ratio of the
clay particles (Chang 2014).
The aim in this chapter was to investigate the effectiveness and influence of two
different processes (melt and solution intercalation) on the morphology and thermal
properties of TLCP/organoclay nanocomposites in order to obtain a material that
combines the excellent thermal behavior provided by addition of inorganic particles
with the versatility and easy processing characteristics of TLCP composites. The general
goal of this work was to use a minimum amount of clay in the hybrids and still obtain
thermal properties significantly superior to those of the matrix polymer. The properties
of these nanocomposites were studied as a function of the organoclay content of the
TLCP matrix.
Experimental
Materials
The source clay, Kunipia-F (Na
+
-MMT), was obtained from Kunimine Co. (Tokyo,
Japan). By screening this Na
+ -MMT clay with a 325-mesh sieve to remove
impurities, we obtained a clay with a cationic exchange capacity of 119 meq/
100 g. Cloisite 25A (organically modified MMT; C25A) was obtained from
Southern Clay Product Co. (Gonzales, LA, USA). All reagents were purchased
from Aldrich Chemical Co. (Yongin, Korea). Commercially available solvents
were purified by distillation.
Syntheses of Organoclays (C12- and C18-MMT)
A dispersion of Na
+
-MMT was added to solutions of the ammonium salts of
dodecylamine (C12) and octadecylamine (C18). These organophilic MMTs were
obtained through a multi-step route (Park and Chang 2000) and have been termed
C12-MMT and C18-MMT, respectively.
21 Characterizations of Nanocomposites of Liquid Crystalline Polymers
581