Diisocyanate definition

With the development of polymer science and the synthesis of new polymers, the previous definition of condensation polymer is inadequate. For example, in polyurethanes (Table 1.2), which are classified as condensation polymers, the repeating unit has the same net composition as the two monomers (i.e., a diol and a diisocyanate), which react without eliminating any small molecule. To overcome such problems, chemists have introduced a definition which describes condensation polymers as consisting of structural units joined by internal functional groups... 

Definition Rubber-like polymer resulting from combination of castor oil with sulfur or diisocyanates... 

Definition Polymer of diphenylmethane 4,4 -diisocyanate Toxicoiogy LD50 (oral, rat) > 10 g/kg, (skin, rabbit) > 9400 mg/kg low toxicity by ing. and skin contact questionable carcinogen tumorigen TSCA listed... 

PH3 (2 to 4 atm) reacts with organic isocyanates, XC6H4NCO (X = H, p-Cl, P-NO2 [172] a77-CH3 [173]), in benzene in the presence of triethylamine or tributylamine to give tricarbamoyl-phosphanes, (XC6H4NHC(0))3P. Ethyl, octyl (in the presence of tripropylamine at lOO C and 340 atm), or 1-naphthyl isocyanate react analogously [173]. The reaction of 2,4-tolylene diisocyanate with PH3 is slow, and no definite product could be isolated. Phenyl isothiocyanate failed to react with PH3 under reaction conditions analogous to those for the isocyanates [172]. 

Note The definition ignores loss of double bonds. The Carothers definition fails to describe all the polymers that can fit into the category of condensation polymers, yet form without an evolution of a byproduct. An example is a polyurethane that can form from a reaction of a glycol with a diisocyanate ... 

Castor oil phosphate polymer with 3-isocyanatomethyl-3,5,5-trimethyl cyclohexyl isocyanate Castor oil, polymer with 5-isocyanato-1 -(isocyanatomethyl)-l, 3,3-trimethylcyclohexane, phosphates. See Castor oil phosphate/lPDI copolymer Castor oil, polymerized Synonyms Polymerized castor oil Definition Rubber-like polymer resulting from combination of castor oil with sulfur or diisocyanates... 

Definition Copolymer of PEG-8 and sat. methylene diphenyidiisocyanate (dicyclohexylmethane diisocyanate) monomer Formuia [C15H22N2O2 (C2H40)nH20]x Toxicoiogy TSCA listed Uses Film-former, emollient, spreading agent, deposition and delivery system for topical cosmetics... 

Synonyms Benzene-, 1,3-diisocyanatomethyl- Diisocyanatomethylbenzene 1,3-Diisocyanatomethylbenzene Diisocyanatotoluene Isocyanic acid, methyl phenylene ester Isocyanic acid, methyl-m-phenylene ester Methyl-m-phenylene diisocyanate Methylphenylene isocyanate TDI TDI 80-20 Toluene diisocyanate mixed isomers Tolylene diisocyanate Tolylene isocyanate Definition Mixt. of the 2,4-isomer (89.3%) and the 2,6-isomer (10.7%)... 

Condensation polymers by the above definition are usually produced by step-growth polymerizations but not all step-growth syntheses are condensation reactions. Thus there is no elimination product in polyurethane synthesis from a diol and a diisocyanate (cf. reaction (1-12)) ... 

In aromatic diisocyanates, such as toluene dissocyanate (TDI), one isocyanate gronp can modify the activity of the other, and the activity of both groups can depend on the other snbstituents of the aromatic ring. For a mixture of 2,4 and 2,6 isomers of TDI (industrially, it is difficult to separate the two), 12 reactions with primary and secondary lOH groups of the polyols have been identified. The rate constants for these reactions have been measured experimentally and are summarized in Table 3.4. Significant differences can be observed in the reactivity of the two —NCO groups the equal reactivity hypothesis is definitely not followed. There have been several fundamental studies to model the unequal reactivity of functional groups in urethane formation. It has been shown that such reactivity has considerable influence on the polymer formed. 

The definite amounts of polyelher-based polyol, catalyst, surlactant and foaming agent premixed thoroughly in a disposable cup, and then the prescript amount of 4,4 -diphenylmethane diisocyanate(MDI) was added and mixed at a stiring speed of SOOOrpm for 10-15seconds. The mixture was poured immediately into a cardboard box and was allowed to rise at room conditions. The foam mataial was removed from the box after one hour and was allowed to cure at room tenperature for two days. Here, five kinds of foam materials wo e employed. 

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