Polyacrylonitrile, 413 Table

DTDM AC is adsorbed best on cotton and wool. Significantly lower amounts of softener are adsorbed on synthetic fibers, which are nonpolar and hydrophobic, such as polyester and polyacrylonitrile. Table 9.4 shows the relative amounts of softener sorption in percentage WOF (weight of fabric) from distearyldimethyl ammonium bromide (DSDMAB) solutions (wt/v%) [59], Although a lower amount is adsorbed on polyester, in subjective sensory evaluations the softness rating of polyester fabric was similar to that of cotton [59],... 

PyraZolines. l,3-Diphenyl-2-pyia2olines (7) (Table 2) aie obtainable from appiopiiately substituted phenyUiydiazines by the Knoii reaction with either P-chloro- or P-dimethylaminopropiophenones (30,31). They are employed for brightening synthetic fibers such as polyamides, cellulose acetates, and polyacrylonitriles. 

Fig. 15. Oxygen permeability versus 1/specific free volume at 25 °C (30). 1. Polybutadiene 2. polyethylene (density 0.922) 3. polycarbonate 4. polystyrene 5. styrene-acrylonitrile 6. poly(ethylene terephthalate) 7. acrylonitrile barrier polymer 8. poly(methyl methacrylate) 9. poly(vinyl chloride) 10. acrylonitrile barrier polymer 11. vinyUdene chloride copolymer 12. polymethacrylonitrile and 13. polyacrylonitrile. See Table 1 for unit conversions.

Select mobile phases for HPSEC based on their ability to dissolve the sample and their compatibility with the column. Zorbax PSM columns are compatible with a wide variety of organic and aqueous mobile phases (Table 3.4), but analysts should avoid aqueous mobile phases with a pH greater than 8.5. As mentioned earlier, select mobile phases that minimize adsorption between samples and silica-based packings. Sample elution from the column after the permeation volume indicates that adsorption has occurred. If adsorption is observed or suspected, select a mobile phase that will be more strongly adsorbed onto the silica surface than the sample. For example, N,N-dimethyl-formamide (DMF) is often used for polyurethanes and polyacrylonitrile because it eliminates adsorption and dissolves the polymers. When aqueous mobile phases are required, highly polar macromolecules such as Carbowax can be used to coat the silica surface and eliminate adsorption. Table 3.5 provides a list of recommended mobile-phase conditions for some common polymers. 

Polyacrylonitrile (C3H3N) bums to form vapor, carbon dioxide and nitrogen. The heat of formation of the polyacrylonitrile is +15.85 kcal/g mol (1 cal= 4.186 kJ). Use data from Tables 2.1 and 2.2 use specific heat values at 1000 K. 

The individual values of vA, vB and vc have been excluded from Table 15 and indeed for this system the value of vB can only be measured in three solvents due to the insolubility of polyacrylonitrile in the others. For the purpose of calculating (vA - vB)/v, the value would have to be interpolated rather less accurately via Eq. (110). In the same order as the solvents listed in Table 15, the values of(t>A — vc)... 

Table 10.2 outlines the uses of acrylonitrile. One important use of acrylonitrile is in the polymerization to polyacrylonitrile. This substance and its copolymers make good synthetic fibers for the textile industry. Acrylic is the fourth largest produced synthetic fiber behind polyester, nylon, and... 

Polyacrylonitrile was ground under a constant pressure of one atm with vinyl chloride and with butadiene to give graft and block copolymers as well as minor amounts of homopolymer in the first system (27). The products were characterized by chemical and infrared analysis, viscometric and turbidimetric measurements, and solubility. The results are reported in Table 4. 

Table I. Solubility of Cellulose in Polyacrylonitrile Copolymers of Cellulose in Cupriethylenediamine (0.5M) at 25°C...

Table II. Infrared Spectral Data of Polyacrylonitrile Copolymers of Cellulose...

Table III. Copolymer Density of Polyacrylonitrile Copolymers of Cellulose Breaking Strength Density, Polyacrylonitrile, of Fibrous Copolymer, grams/ml % X 10 gram ...

Table IV. Effect of Method of Initiation of Copolymerization Reaction on the Properties of Polyacrylonitrile—Cotton Copolymer Fabrics (Print Cloth)...

Table V. Elastic Recovery Properties of Fibrous Cyanoethylated Cotton Cellulose (D.S. 0.7) (62%)—Polyacrylonitrile (38%) Copolymer...

Di(l-methylbenzimidazol-2-yl)furan [ 4751-43-3] [81], which has the ability to form salts, was one of the first cationic benzimidazole brighteners. More recently, cationic benzimidazoles have been developed as brilliant, chlorine-fast, lightfast brighteners for polyacrylonitrile and cellulose acetate (Table 7.7). They are marketed in the form of cold- and heat-resistant concentrated aqueous solutions with long shelf lives. 

The tertiary and quaternary amine salts of l,3-diphenyl-2-pyrazoline derivatives (Table 7.9) are brilliant, moderately lightfast brighteners for (modified) polyacrylonitriles. Some can also be used to brighten cellulose acetate. Depending on the structure and nature of the anion, concentrated aqueous solutions with long shelf lives can be obtained such products are needed, for example, in gel brightening. 

Later workers, chiefly in Japan, used naphthalimides with alkoxy substituents at the 4- or 4,5-positions and obtained brighteners with good lightfastness for polyester substrates and good chlorite fastness for polyacrylonitriles. The first commercial product was 4-methoxy-iV-methylnaphthalimide (64) [3271-05-4] [113], Table 7.10 lists the most important compounds. 

A list of typical commercial pervaporation membranes [23] is given in Table 3.1. Commercial hydrophilic membranes are very often made of polyvinyl alcohol (PVA), with differences in the degree of crosslinking. Commercial hydrophobic membranes often have a top layer in polydimethyl siloxane (PDMS). However, a wide variety of membrane materials for pervaporation can be found in the literature, including polymethylglutamate, polyacrylonitrile, polytetrafluoroethylene, polyvinylpyrrolidone, styrene-butadiene rubber, polyacrylic acid, and many others [24]. A comprehensive overview of membrane materials for pervaporation is given by Semenova et al. [25],... 

Other membrane materials include mainly polyimide, polyacrylonitrile and polybenzimidazole. An overview of commercially available membranes is given in Table 3.2. These membranes are manufactured in procedures usually derived from practical experience by using high-throughput screening, it was shown that optimization is possible [26]. Many other membrane materials are described in the scientific literature and in patents an overview is given by Cuperus and Ebert [27]. 

As mentioned in Section V.H.2, highly important room temperature polymeric systems are based on polyacrylonitrile (PAN) plasticized with PC and EC. These systems are obviously highly reactive with lithium. It is clear that Li, in contact with these membranes, develops surface chemistry which is dominated by the reduction of EC and PC to R0C02Li (Table 3 and Schemes 1 and 3, Section V.C, and related discussion). 

Polymers containing plasticizing solvents. Addition of solvents such as EC or PC to the polymeric systems of the types shown in Table 10 improves their conductivity considerably. Of special importance are conducting polymeric membranes based on polyacrylonitrile (PAN) containing EC, PC, and Li salts such as LiC104, LiS03CF3 [382],... 

Polyacrylonitrile is also quite insoluble in benzene, so that dilution of the monomer with benzene does not change the heterogeneous polymerization in any essential way. The effect of dilution on the specific surface is shown in Table III. There is a discernible trend toward lower surface areas at low acrylonitrile concentration. This is also evident in electron micrographs (Figure 2), where the particles from a benzene-acrylonitrile mixture are more compact and dense in appearance than those in Figure 1. Nevertheless, the surface is still extensive, and this has profound effects on the rate of polymerization. 

Table I gives the composition of the grafting products investigate. The monomers are listed in the order of their increasing tendency to graft— i.e., in the order of an increase in the degree of grafting of the monomer and of the grafted backbone portion. A similar sequence was determined by Hayes for the grafting of vinyl chloride, vinyl acetate, and styrene by emulsion polymerization on poly (vinyl chloride), polyacrylonitrile, or poly (vinyl acetate) (7). Obviously, the sequence in Table I corresponds to the order of the relative activities of the monomer radicals according to Mayo and Walling.

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