Polyureas properties

Cycloahphatic diamines react with dicarboxyUc acids or their chlorides, dianhydrides, diisocyanates and di- (or poly-)epoxides as comonomers to form high molecular weight polyamides, polyimides, polyureas, and epoxies. Polymer property dependence on diamine stmcture is greater in the linear amorphous thermoplastic polyamides and elastomeric polyureas than in the highly crosslinked thermo set epoxies (2—4). 

Example 6. High Solids, Two-Component, Clear, Aliphatic, Polyurea Coating. This example of an aliphatic, 100% urea coating utilizes polyaspartic esters as reactive diluents (see Section 4.2.3). These compounds allow fine tuning of reactivity and physical properties and eliminate the need for viscosity-reducing solvents. 

The polyether-PDMS soft segments in segmented polyurea-urethanes have been synthesized to combine the good mechanical properties of PUs and the excellent blood-contacting properties of PDMS. The most widely recognized material in this category is Avcothane [Arkles BC, Med Device Diagn Ind 3 30(1981)], which is characterized as a block copolymer of aromatic polyether urethane and PDMS. 

Aliphatic iodine derivatives, 14 376 Aliphatic ketones, 14 563, 571, 581-585 reactions of, 16 331-332 Aliphatic monothiopolyesters, 23 739 Aliphatic nitration, 12 187 Aliphatic peroxyacids, 13 464 Aliphatic peroxycarboxylic acids, 18 463 Aliphatic phosphines, 19 60 Aliphatic polyamides (PA), 10 207-210 19 713, 739. See also Aromatic polyamides PA entries producers of, 10 210 properties of, 10 208, 209t Aliphatic polycarbonates, 24 703 preparation of, 19 798 Aliphatic polyketones (PK), 10 197 costs of, 10 222 properties of, 10 198t Aliphatic poly(monosulfide)s, 23 702-704 Aliphatic polyphosphonate dyes, 9 480 Aliphatic poly(polysulfide)s, 23 711 Aliphatic polysulfides, 23 734 Aliphatic polysulfoxides, 23 733 miscibility of, 23 735 Aliphatic polyurea preparation, carbonyl sulfide in, 23 625... 

Property Polyurea Epoxy Poly(cyclo pentadiene) Block copolyamide A-B-A... 

Polythiophenes, with ferrocene groups, 12, 305 Polyurea microcapsules, Pd-containing, 12, 713-714 Poly(vinylcymantrene), synthesis, 12, 311 Poly(vinylferrocene), preparation and properties, 12, 301 Polyynes... 

These membranes have exceptional properties, including seawater salt rejections of up to 99.6 % and fluxes of 23 gal/ft2 day at 800 psi. Unfortunately, they are even more sensitive to oxidants such as chlorine or dissolved oxygen than the polyamide/polyurea interfacial composites. The membranes lose their excellent properties after a few hundred hours of operation unless the feed water is completely free of dissolved chlorine and oxygen. A great deal of work was devoted to stabilizing this membrane, with little success. 

Polyurea Polyurethane Porosity Post cure glycols, glycerol, and polyesters. A polymer containing the urea group -NH-CO-NH-. A polymer containing the urethane group -NH-CO-O-. The presence of numerous small cavities. Heat treatment to which a cured or partially cured thermosetting plastic or rubber composition is subjected to enhance the level of one or more properties. 

In this paper, the surface grafting of rayon fabrics with nitrogen and phosphorus containing polymers in cold plasma is studied. The analytical data (IR spectroscopy, TGA, electron microscopy, elemental analysis, etc.) indicate the formation of grafted copolymers. The grafted rayon fabrics present improved flame-retardant properties, the best behavior was proved by those grafted with polyurea of phosphinic acid. 

Thermoset polyurethanes are cross-linked polymers, which are produced by casting or reaction injection molding (RIM). For cast elastomers, TDI in combination with 3,3,-dichloro-4,4,-diphen5lmethanediamine (MOCA) are often used. In the RIM technology, aromatic diamine chain extenders, such as diethyltoluenediamine (DETDA), are used to produce poly(urethane ureas) (47), and replacement of the polyether polyols with amine-terminated polyols produces polyureas (48). The aromatic diamines are soluble in the polyol and provide fast reaction rates. In 1985, internal mold release agents based on zinc stearate compatibilized with primary amines were introduced to the RIM process to minimize mold preparation and scrap from parts tom at demold. Some physical properties of RIM systems are listed in Table 7. 

The behavior of two other formulations, microcapsules and small plastic laminate flakes, containing tetradecenol formate, were compared in applictions to plots of mature corn at Beltsville, in August 1980. (8) The Z-9-tetradecen-1-ol formate (TDF) is a mating disruptant, rather than a true pheromone, of the Heliothis species of moths. It was selected in these experiments because reliable analytical methods were available (9) and its behavior was expected to be similar to that of the actual pheromones, whose chemical structures and properties are also similar. The two formulations were polyurea-polyamide microcapsules 5-microns in diameter supplied by ICI at Bracknell, Berkshire, England, and a small (3 mm side) plastic laminate formulation supplied by the Herculite Corporation of York, PA. The microcapsules were applied at 300 g of TDF per hectare and the flakes at 285 g/h. Both formulations were applied by air to mature corn 240-270 cm in height in clear, hot weather with a daily maximum temperature of 39°C. 

Low modulus elastomers are materials that have found wide use in the automobile industry for fascia, bumper covers, and trim parts. Other applications include integral window seals and a wide variety of applications where it is replacing molded rubber. Most of these materials are not pure polyurethane, but polyurethane/polyurea hybrids with improved processing and properties when compared with the earlier allurethane systems. 

Hong K, Park S (2000) Polyurea microcapsules with different structures preparation and properties. J Appl Polym Sci 78(4) 894-898... 

Properties of fibers can be altered by carrying out interfacial polymerizations on their surfaces. Thus the shrink resistance of wool can be improved by immersing the fiber first in a solution containing one component of a condensation polymer and then immersing it in another solution containing theother component. Polyamides, polyurethanes, polyureas, and other polymers and copolymers may be grafted on wool in this manner. 

For the polyureas prepared by the polyaddition reaction of uracil and adenine with hexamethylene diisocyanate, and the polyurethanes containing pendant nucleic acid bases, base-base interactions were studied spectrt opically. The polymers were tested further for their anticlotting property . ... 

This prepolymer (Scheme 1.10) is then reacted with a chain-extender diol or diamine to give the final polyurethane or polyurethane-polyurea block copolymer, respectively. The diversity in properties that the final urethane block copolymers exhibit is governed by the nature of the three building blocks the diol-terminated polyester, the di-isocyanate-terminated polyurethane and the chain extender (Hepburn, 1982). As shown in Figure 1.17, these form flexible blocks (from the polyester) that undergo phase segregation as structures of size 1000-2000 nm. 

Polymea mictocapsules containing 0,0-3,5,6-trichloro-2-pyridyl phosphorothioate (Dursban) were prepared by reacting a polyisocyanate and a poly amine and the factors affecting the formation of the microcapsule wall examined. The formation of polyurea was confirmed by FTIR spectroscopy, the thermal properties of the microcapsules were investigated by DSC and the morphology of the microcapsules detenninedby scanning electron microscopy. Optimum conditions for the formation of a thin surface l er and a porous matrix were established. 9 lefs. 

There is an alternative method of making functional derivatives for polymerization. Durene can be condensed with formaldehyde in the presence of hydrochloric acid and zinc chloride to give the bis-chloromethyl durene(75). This can be converted into a number of derivatives from which polymers can be made, e.g. durene-1,4-dicarboxylic acid for polyamides(76), the diacetic acid for polyesters(77,78) or for polyamides(79), the diisocyanatomethyl derivative for polyureas and polyurethanes(80,81), the dimethanol derivative for polyurethanes(82) and for epoxies(83), while the bis chloromethyl derivative has also been proposed for making polyethers (with bisphenol A)(84). In each case, the attraction from the durene derivative has been the introduction of higher melting points and inproved softening properties. None of these polymers have been commercialized, possibly in part because of the difficulty of obtaining durene at suitable-prices. 

No such delay, however, is observed in formation of diarylurea. While no direct measurement is yet available, it is taken that "gel profile" measures association of the polyureas into domains. In "HR" foams this domain formation is delayed, permitting larger, more completely aligned polyurea domains and accounting for the principal property characteristics which distinguish high resiliency foam 3). 

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