Microporous fillers

In polymeric mixed matrix membrane that are used in gas separation applications microporous fillers are used. Soluble polymers of intrinsic microporosity are incorporated as microporous fillers. 

Lower-density E-plastomers have found alternate use in cast film processes to make elastic film laminates with good breathability which contain laminates of liquid impermeable extensible polymeric films with extensible-thermoplastic-polymer-fiber nonwovens and nonwoven webs of polyethylene-elastomer fibers as the intermediate layers. The development relates to a breathable film including an E-plastomer and filler that contributes to pore formation after fabrication and distension of the film. The method and extent of distension is designed to produce a breathable film by stretching the film to form micropores by separation of the film of the E-plastomer from the particulate solids. This film is useful for manufacture of absorbent personal-care articles, such as disposable diapers and sanitary napkins and medical garments. In detail, these constructions comprise a liquid impermeable extensible film comprising polyolefins. The outer layer contains extensible-thermoplastic-polymer-fiber nonwovens, and an elastic intermediate layer contains nonwoven webs of fiber E-plastomers. The intermediate layer is bonded to the film layer and the outer... 

Thin zeolite sheets offer improved mass transfer for possible rapid cycle adsorption processes. One of the first studies of zeolite as fillers in paper-making was issued to NCR in 1955, although at that time the term zeolite was more often used to describe any ion exchanger whether or not it was actually a crystalline microporous zeolite [95]. A later patent described the incorporation of micropo-rous zeolite powders in paper sheets [96]. More recently a number of patents described zeolite-containing papers in adsorption processes [97-99]. 

Recently Serenyl used a flexible alkaline separator (FAS) in Silver—Zinc cells, which consists of a microporous polyolefin film, with inorganic filler. This can be folded around the silver and/or zinc electrodes to form conventional U wraps or heat sealed bags. They showed that the FAS was not attacked by the electrolyte and helps in inhibiting the shape change of zinc electrode. 

The single selection of particle diameter for the characterization of a reinforcing filler is, however, not appropriate, because, on the one hand, only fillers exhibiting a very poor reinforcing effect consist of independent spherical particles, and, on the other hand, gum-filler interactions taking place at the elastomer-filler interface are thus conditioned by the accessibility of the surface. The latter may, indeed, be restricted either by the presence of micropores or by the size of the macromolecule. The knowledge of the specific surface area of the filler is thus a prerequisite. Insofar as the determination of the filler specific surface area, performed by low-temperature gas adsorption or iodine adsorption, takes into account its microporosity, the adsorption of larger tensioactive molecules will often be favored 12,13). 

The carbonization of a syntactic foam opens up the previously closed cell structure. The size and proportion of micropores formed depend mainly on the size and shape homogeneity of the filler. Thus, there is quite a narrow size distribution of open pores in the carbonized material made from a novolac oligomer and Krecasphere carbon microspheres (Fig. 9)39). 

Zeolites are a subclass of microporous materials in which the crystalline inorganic framework is composed of four-coordinated species interconnected by two-coordinated species. Traditionally these materials are aluminosilicates however, many different compositions have been synthesized. The templates used in the synthesis of microporous materials are typically small ionic or neutral molecular species. The function of the template in the synthesis of microporous materials is little understood, and there are at least four different modes by which an additive can operate in a zeolite synthesis a) It may act as a space filler occupying the voids in the structure, thereby energetically stabilizing less dense inorganic framework b) the additive may control the equilibria in the synthesis mixture, such as solution pH or complexation equilibria c) it may preorganize the solution species to favor the nucleation of a specific structure d) it may act as a true template determining the size and the shape of the voids in the structure. 

Many effects can be produced by the pores in filler particles. One is that pores in silica reinforce rubber. During mixing, rubber chains migrate into the pores which increase the adhesion between the phases. The selective absorption of low molecular weight components affects the performance of paints and other materials. Microporous membranes and fibers are produced to clean water and selectively absorb certain solutes. 

Acid jellying separator. Recently, a microporous separator known as the Acid Jellying Separator (AJS) has been developed [42]. This is a highly filled polymer separator with fumed silica as the major filler component. Important properties of the AJS are given in Table 7.18 for a sample with a thickness of 1 mm... 

In carbon, the conductivity varies from 10 (ohm-cm) for amorphous carbon to approximately 300 (ohm-cm) in the longitudinal direction for PAN-based high modulus carbon fibers. Apart from relatively low conductivity, carbon has the same magnetic permeahUity as aluminum, i.e., approximately 1. In order to obtain a given damping, carbon-based fillers have to he added in higher concentrations in comparison with metallic fillers such as steel. However, special carhon hlack grades with microporous structure and increased conductivity can now be found that allow the construction of a conductive network at relatively low concentrations. 

A VIP is obtained by packaging a microporous low conductivity filler material inside a highly impermeable gas barrier bag. The filler is then evacuated to a proper vacuum level and the bag sealed. A gas adsorbent, normally referred to as a getter, inserted in the bag before sealing, is also necessary in most panel designs to ensure the proper vacuum level during the lifetime of the panel. 

Figure 16.5 WVTR versus pore diameter for microporous stretched LLDPE/60% CaC03 films containing different filler grades [21].

The addition of relatively large proportions of insoluble modifiers or fillers can greatly alter the structure and properties of the microporous sheet. Addition of talc and cellulose powder are typical examples. While desirable effects on appearance, feel, absorbency, etc., may be achieved— perhaps also with significant cost reduction—mechanical properties usually deteriorate. 

Preparation of a PP film containing a suitable filler by biaxial stretching to develop microporous structure [2]. 

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