The morphological changes and improvement of membrane properties caused by heat treatment were investigated for polytetrafluoroethylene (PTFE) porous membranes prepared from a fine powder by extrusion, rolling and stretching. The properties of the membrane were significantly changed by heat treatment at temperatures higher than 320°C. Shrinkage diminished and the mechanical strength increased due to the partial melting of PTFE. The increase in mechanical strength was caused by suppression of new fibril formation as a result of the loss of folded ribbon‐like crystalline structures that facilitated fibril structures to be pulled out of the original PTFE particle. The decrease in shrinkage was caused by the transformation of fibrils, formed as a collection of ribbon‐like structures, into a massive fibrous structure, which inhibited the reformation of particles. The most important change of the porous structure caused by the heat treatment was the union of nodes in the direction of stretching resulting in a PTFE porous membrane with larger spatial periodicity. A heat treatment above melting temperature of PTFE was the most effective. However, it was necessary to control the temperature and time in order to restrict the coarseness of the porous structure of the membrane.

Polymeric porous membranes were prepared from polytetrafluoroethylene (PTFE) fine powder by a series of mechanical operations, such as extrusion, rolling, and stretching. The structure of the prepared porous membrane was well characterized by a spatial periodicity of nodes (domain of agglomerated PTFE particles) and fibril domains. The fibrils were highly oriented in the direction of the stretching operation, providing pores in the polymeric membrane as slit‐like voids between adjoining fibrils. The unit size of the periodic structure varied depending on the number averaged molecular weight of PTFE and the stretching conditions, the temperature of stretching, and the stretching rate and stretching ratio. A fibril consisted of several thread‐like structures that were easily formed between PTFE particles due to the rolling operation in parallel with their direction. The dependence of the steady tensile stress in the stretching operation on the PTFE molecular weight was much weaker than that presumed for noncrystalline polymeric systems. The activation energy of 11.3 kJ/mol for the growth of fibrils was only several times as large as the thermal energy at the ambient temperature. These results imply that the thread‐like structures can easily be pulled out of PTFE particles. This view is in accordance with the previously proposed microstructure in PTFE particles.

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The formation of zeolite A (LTA) in the presence of tetramethylammonium cations is studied using in situ small angle and wide angle X-ray scattering (SAXS/WAXS) techniques. The SAXS measurements show the formation of homogeneous precursors 10 nm in size prior to the crystallization of LTA which were consumed during the crystallization. The crystal size is estimated by fitting the SAXS patterns with an equation for a cubic particle, and it is revealed that the final crystal size of the LTA depends on the synthesis temperature. However, although such temperature dependence is noted for the final crystal size, the initial precursor particles size appears to be closely similar (ca. 10 nm) irrespective of the synthesis temperature.

Static microstructures are qualitatively elucidated through some typical macroscopic properties for the sodium bis(2-ethylhexyl) sulfosuccinate (A0T)lwaterln-hexanelsodium chloride and the sodium bis(Zethylhexy1) phosphate (SDEHP)lwaterln-hexanehodium chloride systems in the concentrated region of the surfactants. The AOT microemulsions are composed of spherical aggregates immersed in the organic solvent even if the volume fraction of the aggregates is high. In SDEHP microemulsions, which are composed of cylindrical aggregates in the dilute region, the cylindrical aggregates assemble into a branched structure as the volume fraction of the aggregates (PBS increases. When (PBS 2 0.2, the assemblies are packed densely and overlap mutually, and consequently, a transient network structure expanded all over the SDEHP microemulsion is formed. The geometrical form of the individual aggregates in the dilute region strongly influences the microstructure of the microemulsion in the concentrated region.