Isocyanate continued components

The foams were prepared by first mixing the bark and the isocyanate, the other components (catalyst, surfactant, and blowing agent) were pre-mixed and added to this bark - isocyanate mix, and the mixing was continued to yield a homogeneous blend which began to rise and yield a foam product. The rate of foaming was a function of the catalyst used. 

Cellular poly(carbodiimides) derived from polymeric isocyanate (PMDI) can be continuously produced using a phospholene oxide catalyst. As the component temperature is increased from 25 °C to 80 °C at a constant catalyst level, foam densities decrease with increasing component temperatures, with an expected corresponding decrease in compressive strength. The foam friability also decreases with increasing component temperature. 

Only the epoxide and isocyanate treatments have been reported to add to wood cell wall components to such a degree that they cause the wood structure itself to break apart (2, 80), Other chemical substitution treatments of wood components add to wood up to about 35% weight gain with no cell wall rupture. The epoxide and isocyanate systems seem to swell the cell wall, react with it, and continue to swell and react to the point of cell wall rupture and beyond. 

There has been continued interest in the synthesis of oxazoles from a-diazo carbonyl compounds and nitriles catalyzed by Lewis acids. The BFa-catalyzed reaction of a-diazoacetophenones or methyl p-nitrophenyldiazoacetate with chloroacetonitrile affords 5-aryl-2-chloromethyloxazoles or 2-chloromethyl-5-methoxy-4-(p-nitrophenyl)oxazole, respectively (Equation (19)) <89BCJ618>. The former products react with primary, secondary, and tertiary amines by nucleophilic displacement of the chloride group. Methyl or ethyl isocyanate may be used as the nitrile component to prepare... 

Infrared spectroscopy continues to be one of the principal techniques for structural analysis of polymers and for identifying components of complex formulations. The distinctiveness of important vinyl, alkyl, and aryl chemical structures in the infrared such as ester, amide, nitrile, isocyanate, hydroxyls, amine, and sulfone makes it ideal for the first gross characterization of chemical types present and for following the reactions of these functional groups in curing or degradation studies. 

The manufacture of flexible block foams is carried out in a continuous process. The components (polyol), isocyanate and eventually catalysts) are mixed in the head of the mixing machine and poured in the transverse direction of the moving conveyer belt. The liquid mixture starts foaming to form a large foamed bun, which is then sliced into squares of the desired thickness. Such products could be used directly for mattresses, for example. 

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