Moisture adsorption

PMMA-impregnated sol—gel-derived siUca gels have also been examined (54). Long-wave uv illumination was employed in addition to benzoyl peroxide for PMMA polymerization. This method prohibited the degradation of the siUca xerogel from moisture adsorption and desorption. Overall the material behaved more like bulk PMMA than bulk siUca, with the exception of hardness. 

A new desiccant formulation was prepared from a mixture of submicron-sized silica gel and molecular sieves to achieve the best combination of large water capacity, rapid moisture adsorption and easy regenerability. The formulation also tolerates the presence of VOCs and smokes. Commercial NaX and silica gel were crushed and mixed in the proportion of 1 2 and wash coated on a monolith for testing. The same test cell shown in Fig. 12.7-2 was used. The airflow to the saturator was adjusted to obtain the desired humidity in the feed air. Humidity sensors located at the flow cell inlet and outlet, were used to... 

Chauhan, S.S., Aggrawal, P., Karmarkar, A. and Pandey, K.K. (2001). Moisture adsorption behaviour of esterified rubber wood (Hevea brasiliensis). Holz als Roh- und Werkstoff, 59(4), 250-253. 

Minato, K. (1993). Moisture adsorption characteristics of medium-density fibreboard and its raw wood filler treated with formaldehyde. Mokuzai Gakkaishi, 39(10), 1162-1168. 

The effects of fungal fermentation on the moisture adsorption and retention properties of defatted peanut flour have been reported (28). At 8 and 21OC, little difference was noted between the moisture contents of freeze-dried ferments and untreated samples equilibrated at relative humidities ranging from 14 to 75%. However, marked changes were noted above 75% equilibrium relative humidity (ERH), where the control samples did not adsorb as much moisture as did the ferments. These differences were attributed to an increased ratio of exposed hydrophilic to hydrophobic groups resulting from fermentation. 

Figure 9. Moisture adsorption isotherms of enzyme-treated and nontreated peanut...

Many studies have been conducted on predicting the role of packaging in moisture adsorption by dosage forms. Adsorption of moisture by tablets contained in polypropylene films was successfully modeled from storage temperature and the difference in water vapor pressure between the inside and outside of the packaging... 

The absence of polar groups along the polymer chain results in a low dielectric constant with respect to other common engineering thermoplastics. This represents a clear advantage in electric and electronic applications, but also has useful consequences in processing operations where a low moisture adsorption leads to short drying cycles (or none). 

Padmadisastra, Y. Kennedy, R.A. Stewart, P.J. Influence of carrier moisture adsorption capacity on the degree of adhesion of interactive mixtures. Int. J. Pharm. 1994, 104, R1-R4. 

Ahlneck, C. Alderborn, G. Moisture adsorption and tabletting 11. The effect on tensile strength and air permeabihty of the relative humidity during storage of tablets of 3 crystalline materials. Int. J. Pharm. 1989, 56, 143-150. 

Danjo, K. Kato, H. Otsuka, A. Wakimoto, T. Influence of moisture adsorption on volume shrinkage an diametral tensile strength of sucrose tablets. Chem. Pharm. Bull. 1993, 41, 2147-2150. 

Wurster DE, Peck GE, Kildsig DO. A comparison of the moisture adsorption-desorption properties of corn starch, USP, and directly compressible starch. Drug Dev Ind Pharm 1982 8 343-354. 

This mode of fluoride loss is the reason that alumina shipment and transfers are conducted with minimum exposure to air to avoid moisture adsorption. In addition to losses of these substances, carbon tetrafluoride and hexafluor-oethane, which are stable and relatively nontoxic, are known to form during an anode effect [7] (Eqs. 12.11 and 12.12). The possible greenhouse effects have been examined [30, 31], and practical abatement measures proposed [32]. 

Rogojevic, S. Jain, A. Gill, W.N. Plawsky, J. Moisture adsorption in nanoporous silica xero-gels. Electrochem. Solid State Lett. 2002, 5 (7), F22-F23. 

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