Polyacrylonitrile preparation

Nitrilases In development polyacrylonitrile preparation for better coloration... 

The formation of rings in the pdymer chain by the pdymerization of nitrile groups has also been observed in the bulk pd3rmerization of acrylonitrile by Trifonov and Shopov. In this study of the electroinitiated pdymerization of acrylonitrile with tetraethylammonium perchlorate as supporting electrolyte, the polymer was formed on a germanium prism which was part of an internal reflection spectroscopy device. The appearance of the absorption band at 1570 cm" in the spectrum of Ae yellow colored polymer indicated the presence of conjugated multiple bonds idiich was also supported by uv absorption at a lot r wavelength 304 tun, compared to 271 nm for white polyacrylonitrile prepared by free-radical initiation. 

Highly colored, they have been used to dye cellulose acetate (552) and acrylic fibers (553). Cationic dyes prepared from 2-azothiazoles by simple alkylation on the ring nitrogen (552) have been used increasingly with the introduction of polyacrylonitrile fibers with basic sites that can be colored with such dyes (554). 

The (A/-alkylated) lactam of 8-aminonaphthalenecarboxylic acid (47) also is a valuable dye iatemiediate, eg, for cyclometbine-type dyes used for dyeiag polyacrylonitrile fibers and other synthetics. 1,8-Naphtholactams are prepared in high yield and purity by the reaction of naphtholactones with RNH2 (R = H, Cl—4 alkyl, cycloalkyl, or optionally substituted aryl) in aqueous medium, usually in the presence of bisulfite at 150°C over a period of 15 h (143). 

Polymer Solvent. Sulfolane is a solvent for a variety of polymers, including polyacrylonitrile (PAN), poly(vinyhdene cyanide), poly(vinyl chloride) (PVC), poly(vinyl fluoride), and polysulfones (124—129). Sulfolane solutions of PAN, poly(vinyhdene cyanide), and PVC have been patented for fiber-spinning processes, in which the relatively low solution viscosity, good thermal stabiUty, and comparatively low solvent toxicity of sulfolane are advantageous. Powdered perfluorocarbon copolymers bearing sulfo or carboxy groups have been prepared by precipitation from sulfolane solution with toluene at temperatures below 300°C. Particle sizes of 0.5—100 p.m result. 

Fig. 5. Scanning electron micrographs of hoUow fiber dialysis membranes. Membranes in left panels are prepared from regenerated cellulose (Cuprophan) and those on the right from a copolymer of polyacrylonitrile. The ceUulosic materials are hydrogels and the synthetic thermoplastic forms a microreticulated open cell foam with a tight skin on the inner wall. Pictures at top are membrane cross sections those below are of the wall region. Dimensions as indicated.

The second group includes SAHs obtained by radical grafting of acrylonitrile (AN) on natural polymers, mostly starch, under the action of cerium initiators [43 -46, 50, 51], The proper crosslinked hydrophilic polymer is formed at the stage of alkali hydrolysis of grafted polyacrylonitrile (PAN), the final characteristics depending on many factors, in particular the sort of starch [46], the methods of its preparation [51], the component ratio, etc. The nature of starch is exhibited through... 

Hollow-fiber permeators, 26 22 Hollow fibers, 13 389-390 cellulose ester, 26 19 cellulosic, 26 18-20 ion-exchange, 26 15 mechanical considerations and dimensions for, 26 5-7 natural polymer, 26 23 polyacrylonitrile, 26 23 polyamide, 26 21-22 post-treatment of, 26 13-14 preparation of, 26 3 production of, 19 757 with sorbent walls, 26 26 technology of, 26 27 wet spinning of, 25 816, 817-818 Hollow-fiber spinning processes, 26 7-12 Hollow fiber spinning technology,... 

It is used in industry for preparing Polyacrylonitrile by free radical polymerisation and polyisobutylene by cationic polymerisation. Block copolymers are prepared exclusively by this technique. 

Most of the polymers are better known by their trivial names or trade names. Polymers prepared from single polymers are denoted by prefixing poly- to the name of the monomer, e.g., polyethylene, polypropylene, Polyacrylonitrile, polystyrene, etc. If the monomer has substituents or has a multi-worded name, the name of the monomer is enclosed in parenthesis after the prefix poly-, e.g., poly (methyl methacrylate), poly (vinyl alcohol), etc. Condensation polymers like that derived from ethylene glycol and terephthalic acid are named as poly (ethylene terephthalate). 

It is also possible to prepare polymers with functional groups by partial saponification of polyvinyl esters to give OH groups or polyacrylic esters or Polyacrylonitrile to give COOH groups. Polymer with such functional groups at the chain ends are prepared... 

The textiles printing industry has an appreciable interest in P.Y.17 and applies it in the form of pigment preparations. Where its fastness properties satisfy the specifications and where the use requirements are not too demanding, the pigment is also utilized for spin dyeing purposes. Manufacturer recommendations include media such as polyacrylonitrile and cellulose acetate fibers, on which 1/3 SD pigment prints exhibit a lightfastness which is equal to step 5 on the Blue Scale. 

The high quality of the fastness properties is the basis for frequent pigment use in textile printing. Dry cleaning with perchloroethylene or washing has almost no effect on the color. P.Y.83, sometimes in the form of a preparation, is used for viscose spin dyeing, secondary acetate, and polyacrylonitrile. 

P.R.176 provides very lightfast polyacrylonitrile spin dyeing products. The samples equal step 6-7 on the Blue Scale. Dry and wet crocking may affect the objects to a certain extent. P.R.176 is also used in polypropylene spin dyeing, especially for coarse textiles, such as carpet fibers, split fibers, filaments, bristles, or tape, but also for finer denier yams. A special pigment preparation for this purpose is commercially available. 1/3 SD samples tolerate exposure to up to 300°C for one minute or up to 290°C for 5 minutes. In terms of lightfastness, 0.1% colorations equal step 5-6 on the Blue Scale, while 2% samples match step 7. 

The dyes with long-lived luminescence are particularly attractive since background fluorescence can easily be discarded in time domain measurements. Crosssensitivity to oxygen may be problematic but it can be minimized by utilizing gas-blocking polymers. For example, Kuemer et al. [15] used the precipitation technique to prepare polyacrylonitrile-based beads doped with a ruthenium(II) complex which showed virtually no cross-sensitivity to oxygen. Copolymers of polyacrylonitrile and polyacrylic acid were used to provide the beads with... 

In principle, molecular sieve carbons (MSC) can be achieved by the pyrolysis of thermosetting polymers such as polyvinylidene chloride, polyfurfuryl alcohol, cellulose, cellulose triacetate, polyacrylonitrile and phenol formaldehyde (Koresh 1980). An example is given by Trimm and Cooper (1970,1973) for the preparation of MSC (mixed with metallic compounds) for catalyst systems. A mixture of furfuryl alcohol, platinum oxide and formaldehyde was heated to 40°C and additional formaldehyde was added to ensure the... 

A completely different approach was taken by Koresh and Soffer (1980, 1986, 1987). Their preparation procedure involves a polymeric system like polyacrylonitrile (PAN) in a certain configuration (e.g. hollow fiber). The system is then pyrolyzed in an inert atmosphere and a dense membrane is obtained. An oxidation treatment is then necessary to create an open pore structure. Depending on the oxidation treatment typical molecules can be adsorbed and transported through the system. 

Martin and coworkers tried to prepare carbon tubes from the carbonization of polyacrylonitrile (PAN) in the channels of anodic oxide film (10). A commercially available film with a pore diameter of 260 nm was immersed in an aqueous acrylonitrile solution. After adding initiators, the polymerization was carried out at acidic conditions under N2 flow at 40°C. The PAN formed during the reaction was deposited both on the pore walls and on both sides of the film. Then the Film was taken from the polymerization bath, followed by polishing both faces of the film to remove the PAN deposited on the faces. The resultant PAN/alumina composite film was heat-treated at 250°C in air, and then it was heat-treated at 600°C under Ar flow for 30 min to carbonize the PAN. Finally, this sample was repeatedly rinsed in I M NaOH solution for the dissolution of the alumina film. The SEM observation of this sample indicated the formation of carbon tubes with about 50 xm long, which corresponds to the thickness of the template film. The inner structure of these tubes was not clear because TEM observation was not done. The authors claim that it is possible to control the wall thickness of the tubes with varying the polymerization period. 

Carbon/graphite fibers are prepared from either a polyacrylonitrile or rayon precursor fiber or from a pitch precursor 22,23). In either case, the fibers are treated at high... 

Oxidation of the saturated heterocycle to sulfoxide and sulfone derivatives affords solvents for the preparation of polyacrylonitrile (62BEP613056), or corrosion inhibitors (e.g. 147)... 

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