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Drying capillary stress

Drying without the occurrence of large capillary stresses was obtained with supercritical drying in an autoclave. In this case a mean pore size was obtained which was twice that obtained under normal drying conditions and with a broad pore size distribution in accordance with the expectation for a noncompressed, random packing of particles. [Pg.30]

Finally, we note the value of rinsing the water-deposited film with methanol. As methanol is more volatile and has a lower surface tension, film cracking due to the capillary stresses exerted by the meniscus of the drying solvent on the walls of nanosized pores is reduced. Similar results have been reported by Goh.22 Films thicker than a few hundred nm exhibit cracks due to stresses that result during drying of the film, even after methanol treatment. Eliminating these cracks will require other modifications of the drying process. [Pg.67]

The enhancement of the surface area of ccria-based materials related to the surfactant effect that reduces the surface tension inside the pores by decreasing capillary stress during drying and calcination processes. Better thermal stability is related to the structural arrangement and the morphology of the inorganic-organic... [Pg.73]

This capillary stress (see Eq. (8.3)) is related to, and usually smaller than, the developing drying stress (see below). The larger the capillary stress the larger the drying stress which reaches its maximum at or just after the critical point (see Eq. (8.7). [Pg.293]

With mild drying conditions the presence of capillary stresses might contribute to interparticle "bonds", at harsh drying conditions (20% RH, 90°C) this is not the case. [Pg.296]

Capillary stresses inevitably occur whenever gas-liquid menisci appear at the pore boundaries, during evaporation of the pores hquid. Even if the sUoxane bonds have approximately 50% covalent character, which makes the silica gels much more capable of resisting to evaporative effects than other oxide gels, particular attention must be paid to this really tricky step. As illustrated in a number of review articles [53,54], three main routes are commonly used for drying ... [Pg.25]

Supercritical drying, on the other hand, permits to eliminate capillary stresses. Hence, this process produces monolithic silica aerogels of rather large dimensions (Figure 2.5), if required by a targeted application [59] (Figure 2.6). [Pg.25]


See other pages where Drying capillary stress is mentioned: [Pg.2767]    [Pg.2767]    [Pg.500]    [Pg.251]    [Pg.253]    [Pg.255]    [Pg.52]    [Pg.500]    [Pg.730]    [Pg.1515]    [Pg.349]    [Pg.84]    [Pg.272]    [Pg.251]    [Pg.253]    [Pg.255]    [Pg.274]    [Pg.279]    [Pg.295]    [Pg.296]    [Pg.18]    [Pg.1049]    [Pg.423]    [Pg.143]    [Pg.143]    [Pg.251]    [Pg.253]    [Pg.255]    [Pg.2767]    [Pg.2767]    [Pg.18]    [Pg.279]    [Pg.288]    [Pg.289]    [Pg.655]    [Pg.274]    [Pg.1239]    [Pg.152]    [Pg.260]    [Pg.250]    [Pg.25]    [Pg.28]   
See also in sourсe #XX -- [ Pg.270 , Pg.288 ]




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