Poly resistive property

There has been considerable research on chlorine-resistant RO membranes (48—52). A poly(/n j -2,5 dimethyl)pipera2inthiofura2anainide used in the presence of low (3 mg/L) concentrations of chlorine resulted in a membrane life of three years (48). A copolyamide hoUow-fiber membrane for use in desalination has been developed that is resistant to 0.5 mg/L chlorine (49). Millipore Corporation has also developed a sulfonated polysulfone member that has desirable chlorine-resistance properties. 

The excellent chemical resistance and physical properties of PVA resins have resulted in broad industrial use. The polymer is an excellent adhesive and possesses solvent-, oil-, and grease-resistant properties matched by few other polymers. Poly(vinyl alcohol) films exhibit high tensile strength, abrasion resistance, and oxygen barrier properties which, under dry conditions, are superior to those of any other known polymer. The polymer s low surface tension provides for excellent emulsification and protective coUoid properties. 

The selective separation of water from aqueous solutions of isopropanol or the dehydration of isopropanol can be carried out with different membranes, which contain polar groups, either in the backbone or as pendent moieties. For the dehydration of such a mixture, poly(vinyl alcohol) (PVA) and PVA-based membranes have been used extensively. PVA is the primary material from which the commercial membranes are fabricated and has been studied intensively for pervaporation because of its excellent film forming, high hydrophilicity due to -OH groups as pendant moieties, and chemical-resistant properties. On the contrary, PVA has poor stability at higher water concentrations, and hence selectivity decreases remarkably. 

Sugita, K., S. Nagao and Y. Toriyama The corona resisting property of poly-tetraflnoroethylene. Brit. J. Appl. Phys. 7, 38 (1956). 

Huang, J.-C. Zhu, Z.-k Yin, J. Qian, X.-F. Sun, Y.-Y., Poly(etherimide)/montmori]lonite nanocomposites prepared by melt intercalation Morphology, solvent resistance properties and thermal properties, Polymer 2001, 42, 873-877. 

Poly-alpha-olefins and similar hydrocarbons Synthetic fluids with no specific fire-resistant properties Fire-resistant oil-in-water emulsions containing maximum 20% mass of combustible materials... 

The other development by ICI laboratories which made a vital wartime contribution was poly (methyl methacrylate), widely known as acrylic, Perspex or Plexiglas. First produced commercially in the UK in 1934, its rigidity, transparency and shatter-resistant properties were soon in high demand for glazing, aircraft canopies and protective screens because acrylics provided a lower density, weather-resistant alternative to glass (Figure 2.10). Production of poly (methyl methacrylate) increased 1200 per cent during the period 1940-43 due to the escalation in production of aircraft (Kline, 1944). 

PBO (poly-p-phenylene-2,6-benzobisoxazole) is a so-called ladder shtructure with repeating aromatic structures. It has a very high thermal stability (melting point 650°C) and excellent chemical and fire resistance properties. It has the highest specific tensile strength of all materials but is susceptible to humidity and UV radiation. 

Electrosynthesized composites of poly(l,5-diaminonaphthalene) with polyaniline [146] and with polypyrrole [147] have been described and are reported to offer improved corrosion protection of iron. The corrosion-resistant properties of polyaniline and polypyrrole composite coatings electrochem-ically deposited on low carbon steel [148] were found to be strongly influenced by the applied potential and molar feed ratio of the monomers. 

Poly (etheretherketone) or PEEK, the structure of which is shown in Fig. 16.2, was originally developed primarily for composite applications. It is produced by the step-growth polymerization process of dialkylation of bisphenolate salts. PEEK is a semicrystalline thermoplastic with excellent mechanical and chemical resistance properties that are retained at high temperatures. It has a glass transition temperature or Tg at about 143 °C and melts around 343 °C. It is highly resistant to thermal... 

By using a difunctional dihydrosiloxane and/or divinylsiloxane as hydrosily-lation substrates, polycarbosiloxanes can be obtained that differ from their poly-carbosilane analogues in the thermal and mechanical properties (359-362). The organosilicon polymers of this type, containing both Si—O and Si—C bonds in their backbones, are also called hybrid silicones. Because polycarbosiloxanes have properties intermediate between those of linear polydimethysiloxanes and saturated hydrocarbons, they have been synthesized recently to improve thermal and fuel resistance properties of classical silicones (Scheme 39). 

Blends comprising sulfone polymers and other middle- to high-temperature engineering resins with at least a partially aromatic backbone structure are feasible in many cases. Such blends include sulfone polymer blends with polycarbonates, some polyesters, polyarylates, poly-etherimides, and polyaryletherketones. Blends of PPSF with poly-aryletherketones such as PEEK or PEK are particularly interesting as these blends form very finely dispersed systems with synergistic strength, impact, and environmental stress cracking resistance properties [43, 44]. 

Interest in environmentally degradable polymers began more than thirty years ago, when it was first recognized that the commonly used commodity packaging plastics such as polyolefins, poly(vinyl chloride, polystyrene, and poly(ethylene terephthalate) were accumulating in the environments in which they were discarded, after use. Since these polymers were developed for their resistance properties, it should not have been surprising that they were recalcitrant in landfills and as litter when disposed of in a negligent manner. 

The outstanding protein-resistant properties of poly(ethylene glycol) (PEG)-containing surfaces have been recognized for a long time and extensive experimental and theoretical work has been carried out to elucidate the physics underlying these properties. When interpreted in terms of the steric repulsion theory, the protein resistance of PEG is associated with a high conformational freedom and hence entropy of its solvated... 

The synthesis and the high heat-resistant property of poly [bis (ethynylphenyl)silylene]phenylene have also been reported (80). Poly [(diethoxysilylene)phenylene] was first synthesized by a reaction of (3-bromophenyl)triethoxysilane with magnesium. Then the polymer was treated with (trimethylsilylethynyl)phenyllithium, followed by deprotection of the trimethylsilyl groups. 

The next step in our plan to improve the flame resistant properties of the polyfvinyl alcohol) - nylon-6,6 system was the substitution of pure poly (vinyl alcohol) by poly( vinyl alcohol) oxidized by potassium permanganate (PVA-ox). This approach was based on the fire behavior of the (PVA-ox) itself. It was shown experimentally using a cone calorimeter that there was a dramatic decrease of the rate of heat release and significant increase in ignition time for the oxidized PVA in comparison with the original PVA. 

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