Polarity ketone resin

SAN resins show considerable resistance to solvents and are insoluble in carbon tetrachloride, ethyl alcohol, gasoline, and hydrocarbon solvents. They are swelled by solvents such as ben2ene, ether, and toluene. Polar solvents such as acetone, chloroform, dioxane, methyl ethyl ketone, and pyridine will dissolve SAN (14). The interactions of various solvents and SAN copolymers containing up to 52% acrylonitrile have been studied along with their thermodynamic parameters, ie, the second virial coefficient, free-energy parameter, expansion factor, and intrinsic viscosity (15). 

Chlorinated hydrocarbon solvents and polar solvents such as ketones and ethers may dissolve the CPE resins. 

Acrylonitrile-Butadiene Elastomers. These polymers, the so-called nitrile rubbers , are used dissolved in ketone or other highly polar solvents. When they are compounded with thermosetting phenolic resins it is possible to obtain good resistance to elevated temperatures. 

Lipopholic products are usually separated by extraction of the filtered broth, or the whole culture including the biomass, with water immiscible organic solvents, followed by separation of the solvent extracts and concentration in a vacuum evaporator. Chloroform, dichloromethane and ethyl acetate have been widely used as extraction solvents, however, 4-methyl-2-pentanone (methyl isobutyl ketone) appears to be the solvent of choice in the case of steroid substrates. Hydrophilic products, which cannot be extracted by organic solvents, can be isolated by ion exchange or by selective adsorption to polymeric resins (e.g., Amberlite XAD-resins). Resins of a wide range of polarity are available and lipophilic compounds can also be separated by this method. Final purification is accomplished in the usual way by crystallization, distillation or column chromatography. Preparative HPLC is a powerful tool for purification of small product quantities. 

Initial achievements in this field were carried out by Kobayashi as early as 1978. Copolymerization of 71 with acrylonitrile produced linear polymers 72 (Scheme 10.14), which are soluble in polar aprotic solvents, that were assayed for different Michael additions. In general, good conversions were obtained, but enantioselec-tivities were always below 60% ee [204-206]. In a related approach by Oda, different spacers were introduced between the polyacrylonitrile backbone and the chiral fragment, which resulted in an increase of selectivity up to 65% ee [207]. Addition of thiol groups in PS-DVB resins to the double bond allowed the preparation of the corresponding insoluble polymers 73, which were assayed by Hodge for the addition of thiols to unsaturated ketones and nitrostyrene. Again, selectivities were... 

Unsubstituted and Heat Reactive. The first class, the unsubstituted, heat-reactive resins, are made by using phenol, cresols, and xylenols. They are multifunctional and thus can be cross-linked to form films. They are soluble in alcohols, ketones, esters, and glycol ethers and insoluble in aromatic and aliphatic hydrocarbons. They will tolerate some water in their solvents and, in some cases, are completely water soluble. They are compatible with polar resins such as amino resins, epoxies, polyamides, and poly(vinyl butyral), though compatibility on curing is dependent on reaction between the two resins. Less polar resins such as alkyds and drying oils are incompatible. 

Substituted and Heat Reactive. The third class, substituted and heat-reactive resins, are made by using para-substituted phenols where the substituent is a four-carbon or higher group such as tert-butyl, tert-octyl, and phenyl. Small amounts of ortho-substituted phenols and unsubstituted phenols are sometimes coreacted but, in general, the functionality is 2, and only linear molecules are formed. They are brittle solids that do not form films. The substituent makes the resins less polar and hence they are soluble in ketones, esters, and aromatic hydrocarbons, with limited solubility in alcohols and aliphatic hydrocarbons. The phenolic resins based on longer chain aliphatic phenols are more compatible with drying oils, alkyds, and rubbers. 

Ethanol is a colorless, clear liquid with a characteristic, pleasant odor. It is miscible in all proportions with water and readily miscible with many organic solvents (e.g., ethers, hydrocarbons, acids, esters, ketones, carbon disulfide, glycols, and other alcohols). Ethanol dissolves castor oil, cellulose nitrate with a low nitrate content, polar resins, and polymers. Ethanol in combination with aromatic compounds dissolves cellulose acetate. Mixtures of ethanol, aromatic hydrocarbons, and water are good solvents for some polyamides. Ethanol is extensively used in the chemical and pharmaceutical industries. It is employed as a raw material for many chemical syntheses (e.g., esterification, as an ethylating agent, and reaction medium). Ethanol is an excellent solvent, diluent, and extracting agent for fats, oils, paints, and... 

In terms of polymer matrices for composite materials, there will be a compromise between solvent and water resistance. Thus non-polar resins are likely to be less resistant to hydrocarbon solvents, which have low polarity, but more resistant to moisture absorption. Polar resins behave in the opposite way. Strongly polar solvents, such as dimethyl sulphoxide or similar, can interact with polar structures in the resin and are difficult to resist. Crystalline thermoplastic polymers are often better for such applications. For example, polyethene will only dissolve in hydrocarbon solvents (of similar solubility parameter) at temperatures above the crystalline melting point. Polar semi-crystalline polymers such as the polyamides or nylons can be dissolved in highly polar solvents, such as cresol, because of a stronger interaction than that between molecules within the crystallites. High performance thermoplastic polymers such as polyether ether ketone (PEEK) have been promoted for their resistance to organic solvents (see Table 3.5) [12], The chemical resistance of unsaturated polyester and vinyl ester and urethane resins is indicated in Table 3.6 [15]. 

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