Forming system

Superabsorbents. Water-sweUable polymers are used extensively in consumer articles and for industrial appUcations. Most of these polymers are cross-linked acryUc copolymers of metal salts of acryUc acid and acrylamide or other monomers such as 2-acrylamido-2-methylpropanesulfonic acid. These hydrogel forming systems can have high gel strength as measured by the shear modulus (134). Sometimes inorganic water-insoluble powder is blended with the polymer to increase gel strength (135). Patents describe processes for making cross-linked polyurethane foams which contain superabsorbent polymers (136,137). 

Glass-forming systems other than siUca have been examined. The fraction of three- and four-coordinated boron in borate glasses can be determined by nmr (29). Both nmr and x-ray diffraction (30) results led to the suggestion that the boroxyl ring is the stmctural unit of vitreous The... 

H. Rawson, Inorganic Glass-Forming Systems, Academic Press, Inc., London, 1967. 

Physiological Classifications of Contaminants. The physiological classification of air contaminants is difficult, because the type of action of many gases and vapors depends on concentrations (55). For example, a vapor at one concentration may exert its principal effect as an anesthetic but, at a lower concentration, the same vapor may iujure the nervous system, the hematopoietic (blood-forming) system, or some visceral organ (see Toxicology). 

Carbonate Glasses. Carbonate glasses must be melted under moderate pressures to prevent the escape of carbon dioxide gas. The simplest carbonate glass forming system is K CO —MgCO. ... 

Most investigators have focused their attention on a differential segment of the zone between the feed injection and the crystal melter. Analysis of crystal formation and growth in the recoveiy section has received scant attention. Table 22-4 summarizes the scope of the literature treatment for center-fed columns for both solid-solution and eutectic forming systems. 

D.R. Uhlmann and NJ. Kiiedel. Glass Science and Technology, Vol. I (Glass forming systems). Academic Piess (1983) TP848 G56. 

Di- and tetraynes with hydrogen sulfide in an alkaline medium at 20-80°C form systems containing linked thiophene cycles. Thus, l,4-dithienylbuta-l,3-diyne (47) forms 2,5-di(2-thienyl)thiophene (48) in 78% yield, whereas octa-2,4,6-tiiyn-l-ol (49) under the same conditions gives 5-hydroxymethyl-2-prop-1-ynylthiophene (50) in 50% yield (77HOU947). 

Iron, tris(hexafluoroacetylacetone)-structure, 1,65 Iron, tris(oxalato)-chemical actinometer, 1,409 photoreduction, 1,471 relief-image-forming systems, 6,125 Iron, tris(l,10-phenanthroline)-absorptiometry, 1,549 racemization, 1,466 solid state, 1,467 structure, 1, 64 lron(III) chloride amino acid formation prebiotic systems, 6,871 Iron complexes acetonitrile. 4,1210 acetylacetone, 2,371 amidines... 

Photopolymerizable coatings relief-image-forming systems, 6,125 Photoreactivity environmental effects, 1, 394 Photoredox properties bipyridyl metal complexes, 2, 90 Photoresist systems, 6,125 Photosensitive materials, 6, 113 Photosynthesis anoxygenic, 6, 589 magnesium and manganese, 6, 588 water decomposition models, 6, 498... 

Visceral organs in general Haematopoietic (i.e. blood-forming system) Nervous system... 

Rawson, H. (1967). Inorganic Glass-Forming Systems, Chapter 2. London New York Academic Press. 

Recently, Yoshida and co-worker26 29 have developed a series of new color-forming systems using metal complexes of leuco quinones. Many bidentate ligands that produce a large bathochromic shift of absorption... 

Fig. 6 DSC thermograms showing representative thermal transitions in frozen solutions. The top thermogram is for a mannitol solution and is characteristic of a metastable glass-forming system.

Table I. Values of b for polyester-forming systems derived(21 ) from Figure 5 and plots of X b versus (cac + Cbc)-1 according to equations(7). vA(-/v-fractional length of acid chloride residue in the chain of v bonds, (i) cext = cao + cbo- (ii) cext = cac + cbc For explanation of reactants see Figure 5.

Behaviour similar to that shown by the polyester-forming systems is shown by the several polyurethane-forming systems which have been studied(3,4,6,15,23-28), and Figure 6 and Table II give the results(29) for polyurethane-forming systems from which network materials have been formed at complete reaction. 

In general, compared with the polyester-forming systems, curved... 

The reactants used to form the networks studied are generally of lower molar mass than those used by other workers to form perfect networks (e.g. (35)). However, the present results do indicate that very little pre-gel intramolecular reaction can have a marked effect on modulus. For example, for pr,c = 0.05, or ac = 0.58, with a trifunctional polyurethane-forming system of Me = 635g mol l, the modulus is reduced by a factor of five below that calculated on the basis of the small-strain(affine) behaviour of the perfect network. As a result, it is recommended that the effective absence of pre-gel intramolecular reaction in endlinking reactions to form perfect networks be confirmed by experiment rather than be assumed. 

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