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Humid ageing

Diphosphates. Three 2-chloroethyl diphosphates have been sold commercially. These have low volatihty and good-to-fair thermal stabiUty, and are thus useful ia those open cell (flexible) foams which have requirements for improved resistance to dry and humid aging. [Pg.477]

The product contains 12.6% phosphoms and has an OH number in the 450 mg KOH/g range. Fyrol 6 is used to impart a permanent Class 11 E-84 flame spread rating to rigid foam for insulating walls and roofs. Particular advantages are low viscosity, stabiHty in polyol—catalyst mixtures, and outstanding humid aging resistance. Fyrol 6 is used in both spray foam, froth, pour-in-place, and slab stock. [Pg.479]

Methods can only usefully applied in analytical practice when they are sufficiently robust and therefore insensitive to small variations in method conditions and equipment (replacement of a part), operator skill, environment (temperature, humidity), aging processes (GC- or LC columns, reagents), and sample composition. This demand makes robustness (ruggedness) to an important validation criterion that has to be proved by experimental studies. The concepts of robustness and ruggedness mostly have been described verbally where it must be stated that their use is frequently interchangeably and synonymously (e.g., Hendricks et al. [1996] Kellner et al. [1998] EURACHEM [1998] ICH [1994, 1996] Wunsch [1994] Wildner and Wunsch [1997] Valcarcel [2000] Kateman and Buydens [1993]). [Pg.220]

Aluminum composites. See also Aluminum-filled composites maximum packing fraction of, 70 25-26 spatial charge carriers in, 70 22 weight gain during relative humidity aging, 70 24... [Pg.41]

Z.T. Chowhan, The effect of low- and high-humidity ageing on the hardness, disintegration time and dissolution rate of dibasic calcium phosphate-based tablets. J. Pharm. Pharmacol., 32 (1980) 10. [Pg.340]

S. Kadir, N. Yata, M. Kawata and S. Goto, Effect of humidity aging on disintegration, dissolution and cumulative urinary excretion of p-aminosalicylate formulations. Chem. Pharm. Bull, 34 (1986) 5102. [Pg.340]

A simple and very useful method of studying humid aging consists of exposing an initially dry sample in a medium at constant temperature and relative humidity (or water activity in immersion) and recording weight changes. Various types of gravimetric curves can be obtained the most frequent ones are shown in Fig. 14.1. [Pg.433]

Figure 14.1 Shape of the kinetic curves of mass change in the most frequent cases of humid aging. Figure 14.1 Shape of the kinetic curves of mass change in the most frequent cases of humid aging.
Since both reversible and irreversible processes are influenced in distinct ways by temperature and water activity, the first step of a humid aging study consists of searching for the conditions (T, RH, sample thickness) in which both phenomena can be clearly decoupled, as in Figs 14. lc and d. The interpretation of experimental results and the modeling of the kinetics of property changes would be difficult or even impossible if physical characteristics such as ar d (or better D) were not known. [Pg.434]

In most instances the resistance of cyanoacrylate bonds to humid aging (at 40 °C, saturated humidity) was found to be quite good when there was a reduction of strength on exposure to these conditions no further diminution occurred within three months. [Pg.106]

Chowhan ZT, Amaro AA, Chi LH. Comparative evaluation of aqueous film coated tablet formulations by high humidity aging. Drug Dev Ind Pharm 1982 8 713-37. [Pg.408]

ASTM D 2126-87 Standard Test Method for Response of Rigid Cellular Plastics to Thermal and Humid Aging, 2 pp (DOD Adopted) (FSC 9330) (MR) (Comm D-20)... [Pg.411]

This method provides ten conditions for the thermal and humid aging of rigid cellular plastics. [Pg.411]

This Navy specification covers a single class of foam, nominal density 2.0 Ib/ft rigid unicellular polyurethane foam, and the materials required for preparation by the foam-in-place technique. Requirements cover density, compressive strength, volume change after heat aging, humidity aging, compressive set, unicellularity (% open cells, max.), oil resistance, and fire resistance. [Pg.429]

Method 11 - Humidity aging at an elevated temperature Method 12 - Heat aging... [Pg.444]

Gardner, R.J. Martin, J.R. Humid aging of plastics effect of molecular weight on mechanical properties and fracture morphology of polycarbonate. J. Appl. Polym. Sci. 1979, 24 (5), 1269-1280. [Pg.2287]

Paper FOR KRAFT PAPER SAMPLES Dry Aging Ea Humid Aging Ea... [Pg.123]

In BPDA-PDA, the only hydrolysis observed was of anhydride. If the samples are cured to at least 400 °C to minimize the residual anhydride, the bulk polymer should be quite stable to hydrolysis. In this material, then, the major remaining concerns about hydrolytic stability center on the polymer-substrate interfaces whether possible polymer-metal interactions could result in the formation of hydrolytically unstable products and whether or not agents used to promote adhesion will retain their efficacy under humid aging. [Pg.70]

In practice, it is very important to obtain a high primary hydroxyl content with minimum EO quantity. A high EO content leads to turbid polyether polyols because longer poly[EO] chains are insoluble in liquid polypropylene oxide. The flexible PU foams made with highly ethoxylated polyols have poor humidity/ageing/degradation characteristics and a lower compression strength. [Pg.107]

As a general rule, castor oil and its derivatives confer on the resulting PU hydrophobicity and water repellency. These polyols have an excellent compatibility with the pentanes that are used as blowing agents and the resulting PU foams have excellent resistance to humid ageing degradation. [Pg.449]

Thominette F, Merdas I, Verdu J (2003) Humid ageing of polyetherimide chemical and physical interactions with water. In Mittal KL (ed) Polyimides and other high temperature polymers, vol 2. VSP, Utrecht... [Pg.206]

In chemical practice, primary amine groups are easily oxidized to oximes [21]. The most convenient oxidant cited is hydrogen peroxide at room temperature, but catalytic oxidation with molecular oxygen is also reported (Scheme 28.3). In thin films, the metal substrate could act as such a catalyst Because oximes absorb light at 1670-1649 cm [22, 23], they can be the cause of the aging band at 1660 cm . However, this reaction path does not fully explain why this band is observed only under humid aging conditions. [Pg.460]


See other pages where Humid ageing is mentioned: [Pg.149]    [Pg.352]    [Pg.121]    [Pg.195]    [Pg.852]    [Pg.479]    [Pg.432]    [Pg.112]    [Pg.205]    [Pg.57]    [Pg.77]    [Pg.385]    [Pg.396]    [Pg.396]    [Pg.398]    [Pg.398]    [Pg.399]    [Pg.442]    [Pg.90]    [Pg.502]    [Pg.173]    [Pg.178]   
See also in sourсe #XX -- [ Pg.449 ]




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