Poly hygroscopicity

Finally, the prepolymers forming the binder network as well as the plasticizers should not possess any solvating power for the ammonium perchlorate. For example, poly (ethylene oxides) besides being hygroscopic, dissolve too much oxidizer leading to extremely viscous, non-mixable, propellant batches. 

Polymerization and copolymerization of compounds, such as 8-12 with acrylamide, m.aleic anhydride, and 1-vinylpyrrolidone have been performed. The polymeric purine derivatives are generally hygroscopic poly(9-vinyladenine) is soluble in water and gives a hypochromic effect of 13% with ribonucleic acid in aqueous solution. For a review of polycondensation of functionalized purines see ref 234. 

In the solid state, poly(methylvinyl ether/maleic anhydride) copolymers are a white to off-white free flowing, odorless, hygroscopic powders. In solution, poIy(methyIvinyI ether/ maleic anhydride) is a slightly hazy, odorless, viscous liquid. 

Poly(methylvinyl ether/maleic anhydride) and related free acids are hygroscopic powders and therefore excessive exposure to moisture should be avoided. Aqueous solutions exhibit decreases in viscosity upon exposure to UV light. Polyfmethyl-vinyl ether/maleic anhydride) should be stored in a cool, dry place out of direct sunlight. 

Methanol[67-56-l] (methyl alcohol) is a clear, colorless liquid with a characteristic odor. It is hygroscopic and miscible in all proportions with water as well as with many organic solvents. It is less soluble in fats and oils, and is only partially miscible with aliphatic hydrocarbons. Numerous inorganic substances (e.g., many salts) are soluble in methanol. Methanol has a good solvency for polar resins, cellulose nitrate, and ethyl cellulose. However, oil-modified alkyd resins and polymers, with the exception of poly(vinyl acetate), poly(vinyl ethers), polyvinylpyrolidone and polymethacrylamide, are insoluble. 

Ethyl triglycol [112-50-5] [2-(2-ethoxyethoxy)ethoxy]ethanol, triethylene glycol monoethyl ether] is an almost colorless, neutral, mild-smelling liquid with a low hygroscopicity. It is soluble in water and most organic solvents, but is only partially miscible with aromatic and aliphatic hydrocarbons. Ethyl triglycol dissolves cellulose nitrate, shellac, colophony, ketone resins, maleate resins, chlorinated rubber, alkyd resins, and many other paint resins. It does not dissolve cellulose acetate, poly(vinyl chloride), vinyl chloride copolymers, fats, oils, and rubber. 

Water acts as a plasticizer for many of the early plastics. A sheet of casein, 4 mm thick, absorbs 5-7 per cent of its own weight in 24 hours and 30 per cent in 28 days under normal room conditions (Brydson, 1999). Polyamides, such as nylon, are the most hygroscopic polymers in common use today, containing up to 3 per cent moisture by weight under ambient conditions. In the same environment, cellulose acetate contains 0.8 per cent and poly (methyl methacrylate) and polystyrene 0.1 per cent. Plasticized PVC swells and appears opaque if stored at high relative humidity (RH) (Figure 6.6). Water vapour is an efficient plasticizer for the PVC polymer but is incompatible with commercial ester plasticizers, which are hydrophobic. As a result, the more plasticized the PVC, the less water it absorbs. Because water is only weakly bonded to the PVC polymer, it rapidly evaporates again. 

Uses Soft segment in formation of elastomers such as thermoplastic urethanes, polyether esters, polyether amides, coatings, adhesives and sealants, casting resins, and urethane foams Features Produces elastomeric end-prods, with hydrolytic stability, resist. to microbial attack, low temp, flexibility and elasticity Properties APHA 40 max. wax-like solid sol. in most org. solvs. barely sol. in water m.w. 650 sp.gr. 0.977 (40 C) acid no. 0.05 hyd. no. 166.2-179.5 flash pt. 215 C 0.025% water Storage Hygroscopic protect from moisture and air dry nitrogen blanket should be applied to open containers before resealing Polythix M [Poly-Resyn]... 

Sodium alkane sulfonates are hygroscopic and therefore they have to be shipped in sealed waterproof packages. They are also available in the trade as ca. 35% solutions or 60-70% pastes. These consists of ca. 90% monosulfonate, ca. 10% di- and poly sulfonates, and very small amounts of NaCl and neutral oil. 

Further, aramid paper is less hygroscopic than cellulose paper [40]. However, a poly(ether imide) paper absorbs less water than a conventional aramid paper [41]. Therefore, especially under humid conditions, a poly(ether imide) paper is superior to an aramid paper. 

The highly viscous solution of poly(quinazoline dione) in N-methyl pyrroli-done or dimethyl acetamide can be directly wet or dry spun. The hygroscopic, thermally stable, and poorly burnable fiber is considered for use as protective clothing or as filter mats for hot gas filtration. 

PET membranes (Poretics, polyester, pore size 0.2 pm, membrane thickness 10 pm) were purchased from Osmonics, Inc. Diethylether (99%), 2,2 -azobisisobutyronitrile (AIBN), copper (1) bromide (CuBr) (98%), acetone (min. 99.5%), methanol (99%), ethanol (99%), methyl ethyl ketone (MEK) (99%) and polyethylenimine (hygroscopic) were purchased fiom VWR International and used as received. 4,4-Dinonyl-2,2-dipyridine (DNBP) (97%) and ethyl-2-bromoisobutyrate (98%) were purchased from Sigma-Aldrich. Tetrahydrofiiran (THF) was supplied by the Eh Co. Poly(acrylic acid) (PAA) (25% aqueous solution) and 2,3,4,5,6-pentafluorostyrene (PFS) were obtained from Polyscience Inc. and Oakwood Products Inc., respectively. Glycidyl methacrylate (min 95%) was purchased from TCI, America. 

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