Urea polymers

Physical and Chemical Properties. The reaction of urea and formaldehyde forms a white soHd. The solubihty varies with the methylene urea polymer chain length longer-chain, higher molecular-weight UF polymers are less water-soluble than short-chain polymers. Physical properties of the methylene urea polymers which have been isolated are compared to urea in Table 1. 

Table 1. Physical Properties of Methylene Urea Polymers...

Prior to the development of analytical techniques to quantify specific methylene urea oligomers, methylene urea polymer distributions were characterized by physical (solubihty) methods. Products were separated into three fractions (3). 

The nitrogen content of granular urea—formaldehyde reaction products typicahy ranges from 35 to 42% depending on the methylene urea polymer distribution. 

Once in the soil solution, urea—formaldehyde reaction products are converted to plant available nitrogen through either microbial decomposition or hydrolysis. Microbial decomposition is the primary mechanism. The carbon in the methylene urea polymers is the site of microbial activity. Environmental factors that affect soil microbial activity also affect the nitrogen availabiUty of UF products. These factors include soil temperature, moisture, pH, and aeration or oxygen availabiUty. 

B. Polymeric Urea [Benzene, diethenyl-, polymer with ethenylbenzene, [[[[(1 methylethyl)amino]carbonyt]amino]methyl] deriv.] A 10.0-g. portion of benzylamine polymer beads prepared as in Part A and 125 ml. of tetrahydrofuran (Note 6) are combined in a 300-ml., three-necked, round-bottomed flask equipped with a magnetic stirrer, a dropping funnel, and a condenser fitted with a gas-inlet tube A nitrogen atmosphere is established in the system, and the slurry is stirred while 1.35 g. (0.0159 mole) of isopropyl isocyanate [Propane, 2-isocyanato-] is added. This causes an exothermic reaction, which subsides after about 20 minutes. The mixture is then stirred at room temperature for 22 hours and at reflux for an additional 4 hours. The beads are collected by filtration, washed with 150-ml. portions of tetrahydrofuran (Note 6) and methanol, and dried under reduced pressure over calcium chloride to yield 9.09 g, of the isopropyl urea polymer. 

The Poly urea Polymer of 3,3-Dinitro-1,5-Pentane Di isocyanate and 3,3-Dinitro-1J5-Pentanediamine. 

The Post Nitrated Poly urea Polymer of 3-Nitro-3-Aza-1,5-Pentane Diisocyanate and Water. 

By contrast, membranes U-1, A-2 and X-2 are all chlorine sensitive, each responding in a unique manner. U-1 is a thin film composite membrane, the active layer consisting of cross-linked poly(ether/urea) polymer. A-2 is a homogeneous aromatic polyamide containing certain polyelectrolyte groups. X-2 is a thin film composite membrane of proprietary composition. 

MIPs. These are made by adding a hydrophilic monomer to the polymerization mixture, e.g., HEMA, PETRA, or methacrylamide. Some urea polymers have also been found useful. In some cases, however, the hydrophilized MIPs were less satisfactory, perhaps due to interactions during the polymerization between the hydrophilic and the functional monomer. 

The physicochemical features of the processes of formation, stabilisation and solidification of foams are best studied for a polymer foam from urea-formaldehyde resins. That is why the urea polymer foams are used here below to exemplify the principles of optimisation of the technology for production of polymer foam materials. 

The initial oligomer as an aqueous solution is obtained from the reaction of urea and formaldehyde at 100°C and pH = 5.8-6 [130]. The process of polycondensation occurs in the presence of acidic catalyst and yields a tri-dimensional polymer, releasing water and formaldehyde [131]. Surfactants are added as foaming agent to the initial composition for the formation of urea polymer foams [125,130]. Various additives are employed to improve the sanitary properties of these plastics. For example, ammonium carbonate reduces the content of free formaldehyde, while addition of carbonates of alkaline metals inhibits corrosion [125]. 

The bar graph in Figure 7 compares the triad stereosequence probabilities for the PVF samples examined here with values calculated for an equilibrium stereochemical distribution which would result from epimerization at 50 °C (18). All PVF samples, except for the urea polymer, rather fortuitously have nearly an equilibrium stereosequence distribution. Furthermore, both the precursor PVCF and final PVF derived therefrom have nearly identical p(m) values and stereosequence distributions, so that the effect of racemization during reductive dechlorination (19) is not apparent. 

Formaldehyde/urea condensate Formaldehyde/urea copolymer Form-aldehyde/urea polymer Formaldehyde/urea precondensate Formaldehyde/urea epolymer Formaldehyde/urea resin. See Urea-formaldehyde resin... 

Paraformaldehyde/urea polymer Paraformaldehyde/urea resin. See... 

Synonyms Eormaldehyde copolymer with urea Eormaldehyde/urea condensate Eormaldehyde/urea copolymer Eormaldehyde/urea polymer Eormaldehyde/urea precondensate Eormaldehyde/urea prepolymer Eormaldehyde/urea resin Formalin/urea copolymer Methylolurea resin Paraformaldehyde/urea polymer Paraformaldehyde/urea resin Polynoxylin Polyoxymethylene urea (INCI) UF Ure ormaldehyde adduct Urea/formaldehyde condensate Urea/formaldehyde copolymer Urea/formaldehyde oligomer Urea/formaldehyde polymer Urea/ formaldehyde precondensate Urea/formaldehyde prepolymer Urea, polymer with formaldehyde Classification Amino resin thermosetting resin Definition Thermosetting resin formed from condensation reaction of formaldehyde with urea formu/a (CH,N20 CH2O),... 

CAS 68002-19-7 93686-54-5 EINECS/ELINCS 297-708-7 Synonyms Butylated polyoxymethylene urea (INCI) Butylated urea-form-aldehyde resin Poly (urea-co-formaldehyde), butylated Urea, polymer with formaldehyde, butylated Urea, reaction prods, with butyl alcohol and formaldehyde Classification Eormaldehyde copolymer... 

Urea, polymer with formaldehyde. See Urea-formaldehyde resin... 

Urea, polymer with formaldehyde, butylated Urea, reaction prods, with butyl alcohol and formaldehyde. See Urea-formaldehyde resin, butylated... 

Uses Starch insolubilizer in coatings for paper/paperboard in contact with dry food Regulatory FDA 21CFR 176.180 Glyoxal/urea polymer CAS 53037-34-6... 

Tetrakis (hydroxymethyl) phosphonium sulfate-urea condensation prod. Tetrakis (hydroxymethyl) phosphonium sulfate (2 1), urea polymer. See Tetrakishydroxymethyl phosphonium sulfate-urea condensate 1,3,4,6-Tetrakis hydroxymethyl tetrahydro imidazo (4,5-D) imidazole-2,5-dione. See Tetramethylolacetylene diurea N,N,N, N -Tetrakis (2-hydroxypropyl) ethylenediamine. See Tetrahydroxypropyl ethylenediamine... 

Synonyms Urea, polymer with formaldehyde and 1,3,5-triazine-2,4,6-triamine... 

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