Lamellar/interlamellar composites

Fig. 1. Sketch of the distinction between series (left) and parallel (right) arrangements of lamellar/interlamellar composites with the same crystallinity.

PCH materials offer new opportunities for the rational design of heterogeneous catalyst systems, because the pore size distributions are in the supermicropore to small mesopore range (14-25A) and chemical functionality (e.g., acidity) can be introduced by adjusting the composition of the layered silicate host. The approach to designing PCH materials is based on the use of intercalated quaternary ammonium cations and neutral amines as co-surfactants to direct the interlamellar hydrolysis and condensation polymerization of neutral inorganic precursor (for example, tetraethylorthosilicate, TEOS) within the galleries of an ionic lamellar solid. 

In Table 6.2 it can be noted that the two series of values, so obtained, have a similar dependence on blend composition (except for the PB-l/HOCP 70/30 blend in the series of values obtained from Ai ). The interlamellar regions inducing an increase in the surface entropy of folding. As a consequence, PB-1 lamellar crystals with a less regular fold surface are obtained when the PB-l/HOCP blends are isothermally crystallized from the melt in the examined range of values. 

The interface between the lamellar crystals and the non-crystalline, interlamellar region was studied using the technique of the Gibbs dividing surface. In so doing, one is able isolate the effects of the interface alone, irrespective of thickness of the lamellae and, to some degree, of the interlamellar domain. Therefore, the properties attached to the sharp interface can be used in a three-component model with arbitrary composition, which accounts for the interface contribution explicitly, in addition to the crystal and melt bulk contributions. 

In Figure 6, we can determine several useful variables to explore the effects of crystallization temperatures and branch compositions on the lamellar motphology and the crystallization kinetics. These variables include / , the time to reach the plateau value of Q, the plateau values of long period (L ), lamellar thickness (/< ) and interlamellar amorphous thickness (/ ). The physical meaning of probably... 

The PEO/EMAA and PEO/SHS blends exhibit volume-filling spherulites for all compositions examined in this part of the study (i.e., 20%). These observations, in concert with SAXS results, indicate at least partial exclusion of the diluent into regions between lamellar stacks at these compositions. The distribution of the second polymer between the interlamellar and interfibrillar regions can be estimated using measured bulk crystallinities and correlation function parameters as follows. The volume fraction of lamellar stacks is determined from the bulk and linear crystallinities (v, average electron density difference between crystalline and interlamellar amorphous regions can be determined using eqn. 2. 

It was realised by Takayanagi [50] that oriented highly crystalline polymers with a clear lamellar texture might be modelled in terms of a two-component composite in which the alternating layers corresponded to the crystalline and amorphous phases [51]. The model was later extended to include a parallel component in addition to that in series, and was applied first to describe the relaxation behaviour of amorphous polymers with two distinct phases, and later to crystalline polymers in which the parallel component represented either interlamellar crystalline bridges or amorphous tie molecules threading through the amorphous phase. 

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