Polymeric substances

Mixtures of such polymeric substances with solvents show a line of critical points that in theory end at a tricritical point. (See section A2.5.9 for fiirther discussion of tricritical phenomena.)... 

Most high polymeric substances are composed of carbon chains, but a few contain other elements, and one very important class will now be considered. 

Attempts to characterize polymeric substances had been made, of course, and high molecular weights were indicated, even if they were not too accurate. Early workers tended to be more suspicious of the interpretation of the colliga-tive properties of polymeric solutions than to accept the possibility of high molecular weight compounds. Faraday had already arrived at Cs Hg as the empirical formula of rubber in 1826, and isoprene was identified as the product... 

H. Mark and G. S. Whiby, eds.. Collected Papers of Wallace Hume Carothers on High Polymeric Substances, High Polymers, Vol. I, Interscience Pubhshers, New York, 1940. 

M. F. De Boodt, Soil Colloids and Their dissociation indiggregates NATO ASI Sei. B 215, 1990, pp. 517—556, applications of polymeric substances as physical soil conditioners. 

C2S2, is a red Hquid (mp —0.5° C, bp 60—70°C at 1.6 kPa (12 mm Hg)) produced by the action of an electric arc on carbon disulfide (1 4). The stmcture has been shown to be S=C=C=C=S on the basis of its reactions to form malonic acid derivatives and on the basis of physical measurements. It is unstable and decomposes ia a few weeks at room temperature it decomposes explosively when heated rapidly at 100—120°C with formation of a black polymeric substance (C2S2) (5,6). Dilute solutions ia CS2 are fairly stable, but photochemical polymerisation to (C2S2) occurs. 

Cyclic and Polymeric Substances Containing Antimony-Antimony Bonds. A number of oiganoantimony compounds containing rings of four, five, or six antimony atoms have been prepared. The first such compound to be adequately characterized, tetrakis-l,2,3,4-/f i-butyltetrastibetane [47191 -73-5], Cj H Sb, was obtained by the interaction of a dialkylstibide and iodine (70) ... 

Polymeric substances, (RSb) or (ArSb), have been obtained by the decomposition of primary stibines (67,74), the reaction of primary stibines with hydrogen chloride (68), the treatment of primary stibines with diben2yhnercury (137), or the reduction of dibalostibines (138—140). Most of these polymers have not been well characteri2ed. 

A large number of polymeric substances, (RAs) or (ArAs), are also known (113). They are usually prepared by the reduction of arsonic acids with hypophosphorous acid (100,114) or sodium dithionite (115). Most of these polymers have not been well characterized. An insoluble, purple material, poly(methylarsinidene) [26403-94-1], (CH As), prepared by the interaction of methylarsine and a dihalomethylarsine, however, has been shown by an x-ray investigation to have a ladderlike polymeric stmcture in which the inter-mng distances correspond to one-electron bonds (116) ... 

CgH BiBr2, and diphenylbromobismuthine [39248-62-9] C22H2QBiBr, respectively, with lithium aluminum hydride or sodium borohydride at low temperatures yielded only black polymeric substances of empirical formula C H Bi (33). It has been claimed (34) that dimethylbismuthine and diphenylbismuthine can be used as cocatalysts for the polymerisation of ethylene (qv), propylene (qv), and 1,3-butadiene. The source of these bismuthines, however, was not mentioned. 

E. G. M. Torqvist inj. P. Kennedy and E. G. M. Torqvist, eds., High I oljmers,A. Series of Monographs on the Chemist, Phjsies and Technology of High Polymeric Substances Wiley-Interscience, New York, 1968, p. 57. 

As during diagnostics the major is a selectivity of the suggested devices, the electrode selectivity factors were defined by fixed preventing ion method. As preventing used one polymeric substance to another and synthetic washing means Lotus and OMO that contains cation SAS. The received values of selectivity factors varies in l,l-10 -2,2-10 interval. 

Starch A polymeric substance of glucose molecules and a component of many terrestrial and aquatic plants used by some organisms as a means of energy storage starch is broken down by enzymes (amylases) to yield glucose, which can be used as a feedstock for chemical or energy production. 

Electrolysis of salts of fatty acids gives free radicals which are capable of reacting with added substrates. For instance, when water-free potassium acetate is electrolyzed in the presence of polymerizing substances (e.g., styrene) methyl groups are incorporated as end groups into the polymer. Goldschmidt et ai. analyzed the products formed in the electrolysis of potassium propionate in propionic acid and showed that they could be accounted for by the following reaction sequence ... 

Section 3.2 is an introduction to general nucleation behaviour as first used for low molecular weight materials, that is, non-polymeric substances. This topic is frequently not covered in polymer papers but the extensive work done in this area provides the framework for the theory, and indicates the limitations and problems to be expected in predicting the physical behaviour. 

The molar rate of change of polymeric species of degree of polymerization n in a well-mixed, continuous flow tank reactor is related to the kinetic rate of propagation of unassociated polystyryl anions plus their withdrawal rate in the reactor s effluent. Feed streams are void of polymeric substances, but contain monomer initiator and solvent. 

Some antigens, such as type 3 pneumococcal polysaccharide, EPS and other polymeric substances such as dextrans (poly-D-glucose) and levan (poly-D-fructose) can induce antibody synthesis without the assistance of TH cells. These are known as T-independent (Ti) antigens. Only one class of immunoglobulin (IgM) is synthesized and there is a weak memory response. 

None of these, nor many other polymers for which evidence is to be found in the chemical literature, have been investigated as polymeric substances. 

In an important paper published in 1920 Staudinger deplored the prevailing tendency to formulate polymeric substances as association compounds held together by partial valences.He specifically proposed the chain formulas... 

The statistical approach has since assumed a dominant role in the treatment of the constitution, reactions, and physical properties of polymeric substances. The complexities of high polymers are far too great for a direct mechanistic deduction of properties from the detailed structures of the constituent molecules even the constitution of... 

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