Copolymer of polyacrylonitrile

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 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... 

Superabsorbent polymers are now commonly made from the polymerization of acrylic acid blended with sodium hydroxide in the presence of an initiator to form a polyacrylic acid, sodium salt (sometimes referred to as cross-linked sodium polyacrylate). Some of the polymers include polyacrylamide copolymer, ethylene maleic anhydride copolymer, cross-linked carboxy-methyl-cellulose, polyvinyl alcohol copolymers, cross-linked polyethylene oxide, and starch grafted copolymer of polyacrylonitrile to name a few. The latter is one of the oldest SAP forms created. 

Many conventional polymers cannot be melt-spun because they degrade before melting. Examples are those used to produce the acrylic fibres, such as Orion and Courtelle , which are based on copolymers of polyacrylonitrile, -fCH2CH(CN), and the cellulosic fibres (see section 1.2). 

Still another type of a copolymer is one that possesses backbones composed of one individual polymer and the branches from another one. It is called a graft copolymer, because many such materials were formed by grafting the branch polymers to the polymer backbone. This, however, is not always the case and many graft copolymers were formed by polymerizing the branch copolymer from a different polymer backbone. (The subject of block and graft copolymers is discussed in Chap. 9) A graft copolymer of polyacrylonitrile on polyethylene can serve as an example ... 

Resin and Polymer Solvent. Dimethylacetamide is an exceUent solvent for synthetic and natural resins. It readily dissolves vinyl polymers, acrylates, ceUulose derivatives, styrene polymers, and linear polyesters. Because of its high polarity, DMAC has been found particularly useful as a solvent for polyacrylonitrile, its copolymers, and interpolymers. Copolymers containing at least 85% acrylonitrile dissolve ia DMAC to form solutions suitable for the production of films and yams (9). DMAC is reportedly an exceUent solvent for the copolymers of acrylonitrile and vinyl formate (10), vinylpyridine (11), or aUyl glycidyl ether (12). 

The principal use of the peroxodisulfate salts is as initiators (qv) for olefin polymerisation in aqueous systems, particularly for the manufacture of polyacrylonitrile and its copolymers (see Acrylonitrile polymers). These salts are used in the emulsion polymerisation of vinyl chloride, styrene—butadiene, vinyl acetate, neoprene, and acryhc esters (see Acrylic ester polymers Styrene Vinyl polymers). 

Bead Polymerization Bulk reaction proceeds in independent droplets of 10 to 1,000 [Lm diameter suspended in water or other medium and insulated from each other by some colloid. A typical suspending agent is polyvinyl alcohol dissolved in water. The polymerization can be done to high conversion. Temperature control is easy because of the moderating thermal effect of the water and its low viscosity. The suspensions sometimes are unstable and agitation may be critical. Only batch reaciors appear to be in industrial use polyvinyl acetate in methanol, copolymers of acrylates and methacrylates, polyacrylonitrile in aqueous ZnCh solution, and others. Bead polymerization of styrene takes 8 to 12 h. 

Because the polymer degrades before melting, polyacrylonitrile is commonly formed into fibers via a wet spinning process. The precursor is actually a copolymer of acrylonitrile and other monomer(s) which are added to control the oxidation rate and lower the glass transition temperature of the material. Common copolymers include vinyl acetate, methyl acrylate, methyl methacrylate, acrylic acid, itaconic acid, and methacrylic acid [1,2]. 

Though the increase of the concentration of Ce4+ ions also increases the yield of copolymer, it facilitates at the same time the decrease of the length of polyacrylonitrile blocks due to cerium ions participating in the disruption of the growing chain. 

Bischof (16) used the macroradicals resulting from vibromilling as initiators for synthesis of block and graft copolymers of poly(methyl methacrylate) with poly(vinyl chloride) with polyacrylonitrile. 

Coleman, M. M., Sivy, G. T. Fourier Transform Infrared Studies of the Degration of Polyacrylonitrile) Copolymers I. Introduction and Comparative Rates of the Degradation of Three Copolymers Below 200 °C and Under Reduced Pressure. Preprint submitted to CARBON... 

Stearamidomethylpyridinium chloride is used in waterproofing textiles. It is made by reacting pyridine hydrochloride with stearamide and formaldehyde. Vmylpyridines are used as components of acrylonitrile copolymers to improve the dyeability of polyacrylonitrile fibers. Tile commercially important products are 2-vinylpyndine 4-vinylpyndine and 2-methyl-5-vinylpyridine. Formulas are shown below. 

RUBBER (Synthetic). Any of a group of manufactured elastomers that approximate one or more of the properties of natural rubber. Some of these aie sodium polysulfide ( Thiokol ). polychloiopiene (neoprene), butadiene-styrene copolymers (SBR), acrylonitrilebutadiene copolymers (nitril rubber), ethvlenepropylene-diene (EPDM) rubbers, synthetic poly-isoprene ( Coral, Natsyn ), butyl rubber (copolymer of isobutylene and isoprene), polyacrylonitrile ( Hycar ). silicone (polysiloranei. epichlorohy-drin, polyurethane ( Vulkollan ). 

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)...

In order to obtain a ready-for-use sensor array, the probe was immobilized in a block copolymer matrix (polyacrylonitrile-co-polyacrylamide Hypan), which is completely penetrated by water if exposed to it [102], Prior to immobilization, the sensor membrane was cast onto an optically transparent ethyleneglycol-terephthalate polyester support (Mylar). The resulting sensor foil was glued on a black 96-microwell format matrix. The sensor arrays were analyzed by means of time-resolved RLI and PDI methods (see Sect. 2.1) with an optical set up as illustrated in Fig. 6 at an excitation wavelength of 405 nm. The ratiometric images resulted in similar calibration plots for both methods (Fig. 14). The limit of detection and the dynamic range of this sensor foil are comparable to those observed with [Eu(Tc)] in solution [103]. 

In the spectroscopic method, the grafting percentages were evaluated with the aid of a calibration curve. The calibration was obtained by plotting the grafting percentages calculated on the basis of the percent in weight of polyacrylonitrile over that of bamboo versus the band intensity ratio between the nitrile absorption of polyacrylonitrile and the hydroxyl absorption of bamboo. For each calibration point, a certain given amount of polyacrylonitrile and bamboo were used and the KBr pellets were prepared quantitatively for infrared measurements. The infrared spectra were recorded on a Perkin-Elmer 580 infrared spectrophotometer in absorbance mode. Similar procedures were carried out to obtain the calibration curve for holocellulose-polyacryloni-trile copolymers. 

---