Polyacrylonitrile solubility

Hydrophobic fibers are difficult to dye with ionic (hydrophilic) dyes. The dyes prefer to remain in the dyebath where they have a lower chemical potential. Therefore nonionic, hydrophobic dyes are used for these fibers. The exceptions to the rule are polyamide and modified polyacrylonitriles and modified polyester where the presence of a limited number of ionic groups in the polymer, or at the end of polymer chains, makes these fibers capable of being dyed by water-soluble dyes. 

Polydithiazoles Polyoxadiazoles Polyamidines Pyrolyzed polyacrylonitrile Polyvinyl isocyanate ladder polymer Polyamide-imide Polysulfone Decompose at 525°C (977°F) soluble in concentrated sulfuric acid. Decompose at 450-500°C (842-932°F) can be made into fiber or film. Stable to oxidation up to 500°C (932°F) can make flexible elastomer. Stable above 900°C (1625°F) fiber resists abrasion with low tenacity. Soluble polymer that decomposes at 385°C (725°F) prepolymer melts above 405° C (76l.°F). Service temperatures up to 288° C (550°F) amenable to fabrication. Thermoplastic use temperature —102°C (—152°F) to greater than 150° C (302°F) acid and base resistant. 

Polyacrylonitrile is soluble in TV, V-dimethylformamide (DMF) => the solution can be used to spin fibers. 

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. 

For the case of acrylonitrile, there was an induction time of 24 h. This was attributed to the formation of cyanide radicals which are able to react with polyamidic macroradicals. The interpolymer is composed of two fractions one soluble in dimethyl formamide, whose properties are similar to polyacrylonitrile the other, insoluble in this solvent, whose properties are similar to those of the polyamide. No homopolymer was observed. The presence of acrylonitrile on the graft polymer was demonstrated by IR. 

Acrylonitrile monomer when masticated in the presence of polymer leads to the formation of pseudocrosslinked block copolymers by mechanical scission of soluble block copolymers. The aggregation of the polyacrylonitrile chains of the block copolymer fraction results in the formation of swollen gels when the polymerization products are extracted with solvents from the initial polymer (78-80). 

Carbon Chain Backbone Polymers. These polymers may be represented by (4) and considered derivatives of polyethylene, where n is the degree of polymerization and R is (an alkyl group or) a functional group hydrogen (polyethylene), methyl (polypropylene), carboxyl (poly(acrylic acid)), chlorine (poly(vinyl chloride)), phenyl (polystyrene) hydroxyl (poly(vinyl alcohol)), ester (poly(vinyl acetate)), nitrile (polyacrylonitrile), vinyl (polybutadiene), etc. The functional groups and the molecular weight of the polymers, control their properties which vary in hydrophobicity, solubility characteristics, glass-transition temperature, and crystallinity. 

Basic Dyes. These are usually the salts of organic bases where the colored portion of the molecule is the cation. They arc therefore sometimes referred to as cationic dyes. They are applied from mild acid, to induce solubility, and applied to fibers containing anionic groups. Their main outlet is for dyeing fibers based on polyacrylonitrile. 

These tertiary amino end groups give on further reaction acrylonitrile blocks bounded to polysarcosine such block copolymers are much more soluble than pure polyacrylonitrile. 

Dickey and Coover (57) showed that alkyl phosphites are capable of initiating polymerization of monomers bearing electron acceptor groups. Polymerization is rapid at moderate temperatures and, in the examples given, the polyacrylonitrile is soluble in acetone. 

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

The surface of polymeric materials such as polypropylene (PP), PS, polyacrylonitrile (PAN), and nylon was oxidized by immersing them in aqueous solution of oxidizing agents such as potassium peroxy disulfate under nitrogen purging at high temperatures [14]. Graft polymerization of water-soluble monomers such as AAm, methacrylic acid, and 3-aminopropyl methacrylate has been frequently performed in aqueous solution with the use of ceric ion, for instance, at... 

Most of today s ultrafiltration membranes are made by variations of the Loeb-Sourirajan process. A limited number of materials are used, primarily polyacrylonitrile, poly(vinyl chloride)-polyacrylonitrile copolymers, polysulfone, poly(ether sulfone), poly(vinylidene fluoride), some aromatic polyamides, and cellulose acetate. In general, the more hydrophilic membranes are more fouling-resistant than the completely hydrophobic materials. For this reason water-soluble... 

Cationic (Basic) Dyes. These water-soluble cationic dyes are applied to paper, polyacrylonitrile (e g. Dralon), modified nylons, and modified polyesters. Their original use was for silk, wool, and tannin-mordanted cotton when brightness of shade was more important than fastness to light and washing. Basic dyes are water-soluble and yield colored cations in solution. For this reason they are frequently referred to as cationic dyes. The principal chemical classes are diazahemi-cyanine, triarylmethane, cyanine, hemicyanine, thiazine, oxazine, and acridine. Some basic dyes show biological activity and are used in medicine as antiseptics. 

Amides of 3- or 6-hydroxy-2-naphthoic acid bearing dialkylaminoalkyl residues on the nitrogen atom lead to orange dyes for polyacrylonitrile or paper when coupled with diazotized aniline [20,21] or to red dyes, soluble in glycol ethers and useful for ink-jet printing, when coupled with diazotized 3-amino-4-methoxybenzenesulfonic acid AOV-dicthylam idc [22], and to substantive red dyes when the diazo component is a 2-(4 -aminophenyljbenzotriazole [23],... 

Solvent dyes [1] cannot be classified according to a specific chemical type of dyes. Solvent dyes can be found among the azo, disperse, anthraquinone, metal-complex, cationic, and phthalocyanine dyes. The only common characteristic is a chemical structure devoid of sulfonic and carboxylic groups, except for cationic dyes as salts with an organic base as anion. Solvent dyes are basically insoluble in water, but soluble in the different types of solvents. Organic dye salts represent an important type of solvent dyes. Solvent dyes also function as dyes for certain polymers, such as polyacrylonitrile, polystyrene, polymethacrylates, and polyester, in which they are soluble. Polyester dyes are principally disperse dyes (see Section 3.2). 

Dyes for the coloration of polyacrylonitrile fibers must be soluble in the solvents used for the PAN fiber production process, such as DMF, dimethylacet-amide, and ethylene carbonate. Examples are C.I. Solvent Yellow 147 C.I. Solvent Yellow 163, 58840 [13676-91-0] C.I. SolventRed 202 and C.I Solvent Blue 66, 42799 [58104-34-0] (8) and C.I. Solvent Blue 131. 

When the polymers were analyzed for their content of homopolymer, it was found that the acrylonitrile polymer is soluble in chlorobenzene and the vinyl chloride polymer in toluene. Since chlorobenzene is unable to dissolve polyacrylonitrile and toluene cannot dissolve poly (vinyl chloride), it must be assumed that no homopolymer has been formed. This has been verified by fractionations. It is possible to extract with methanol from the vinyl acetate polymer 33% of a substantially pure polyvinyl acetate with a vinyl acetate content of 95%. Hence, acrylo-... 

Polymerization in miniemulsion is a very suitable technique to avoid this problem since each droplet acts as a nanoreactor. As a result, pure polyacrylonitrile (PAN) nanoparticles were obtained in the size range 100 nmwater phase. This is no restriction for a miniemulsion polymerization process, and the use of a hydro-phobic initiator 2,2 azobis(2-methylbutyronitrile) allows the preservation of the droplets as the reaction sites by droplet nucleation (see Fig. 12). Initiation of the... 

Pure acrylonitrile may polymerize at room temperature to polyacrylonitrile (PAN), a compound that, unlike polyamides and polyesters, does not melt at elevated temperatures but only softens and finally discolors and decomposes. Nor is it soluble in inexpensive low-boiling organic solvents. Because fibers made from it resist the dyeing operations commonly used in the textile industry, the usual practice is to modify it by copolymerization with other monomers, for example, vinyl acetate, styrene, acrylic esters, acrylamide, or vinyl pyridine in amounts up to 15 percent of the total weight (beyond which the final product may not be termed an acrylic fiber). The choice of modifier depends on the characteristics that a given manufacturer considers important in a fiber, the availability and cost of the raw materials in the manufacturer s particular area of production, and the patent situation. 

The residue consists mainly of polyacrylonitrile and copper or copper salts. It is slowly soluble in acetone, more readily soluble in polyacrylonitrile solvents such as dimethylformamide or dimethyl sulfoxide, especially when warmed. 

Dawson et al.159) found that many organic materials such as dioxane, cyclohexane, pyridine, toluene, nitrobenzene, chloroform, ethanol, etc., are soluble to more than 30% by weight in NMA at 40 °C. Even -pentane is soluble to the extent of 5% by weight. Cellulose acetate is soluble to at least 0.5% by weight150) while polyacrylonitrile is essentially insoluble in NMA161). 

Many of the remarks made in the previous section concerning fibres can be applied to the analysis of plastics. Some polymers are soluble in organic solvents and samples may be prepared for direct aspiration into a flame in this way, e.g. MIBK is a suitable solvent for polyesters, polystyrene, polysiloxanes, cellulose acetate and butyrate dimethyl formamide for polyacrylonitrile, dimethyl acetamide for polycarbonates and polyvinyl chloride cyclohexanone for polyvinyl chloride and polyvinyl acetate formic acid for polyamides and methanol for polyethers. These organic solutions may alternatively be injected into a graphite furnace. Otherwise, polymers may be wet or dry ashed and the resultant ash dissolved in acid. An approach which is attracting increasing interest is the direct insertion of solid samples into a graphite furnace. 

Many macromolecular eompounds dissolve in mixtures better than in pure solvents [20]. Thus, poly (vinyl ehloride) is insoluble in acetone as well as in carbon disulfide, but soluble in a mixture of the two. The opposite situation is also known. Malono-nitrile and A, A -dimethylformamide both dissolve polyacrylonitrile but a mixture of the two does not [20]. Soaps dissolve neither in ethylene glycol nor in hydrocarbons at room temperature but are quite soluble in a mixture of the two. Here, ethylene glycol solvates the ionie end, and the hydrocarbon the apolar end of the fatty acid chain [128]. 

Basic (cationic) dyes. Basic dyes are water-soluble and produce colored cations in solution. They are mostly amino and substituted amino compounds soluble in acid and made insoluble by the solution being made basic. They become attached to the fibers by formation of salt linkages (ionic bonds) with anionic groups in the fiber. They are used to dye paper, polyacrylonitrile, modified nylons, and modified polyesters. In solvents other than water, they form writing and printing inks. The principal chemical classes are triaryl methane or xanthenes. Basic brown 1 is an example of a cationic dye that is readily protonated under the pH 2 to 5 conditions of dyeing [5]. 

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