High-polymer formation

3 CONTINUOUS PROCESS FOR THE MANUFACTURE OF BI AXIALLY ORIENTED PEN FILM 

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B. High Polymer Formation with Citrate as Complexing Agent. 132... 

Since the free acids do not take part in polymerization, they prevent high polymer formation and reduce heat resistance. 

Reactions Limiting High Polymer Formation 10.3.1 Macrocyclization... 

However, until recently, the principal application of polyurethanes has been as in situ-polymerized rigid and flexible foams used for insulation and cushioning, respectively.— — Unlike the phenolic, urea and furan mortars, in which the high polymer formation is the result of the chain extension and crosslinking of a prepolymer, the final polyurethane product is the result of a reaction between hydroxyl and isocyanate groups as shown by the following equation ... 

The rate constant for propagation of (polystyrene) Na+ in tetrahydrofinan for 25°C was found to be 400 1-mol s. The rate constants for proton transfer to the anion from water and ethanol were 4000 l-moT s and 4 1-mol sr, respectively. Which of these impurities (water or ethanol) is more likely to inhibit high polymer formation in sodium-catalyzed anionic polymerization of styrene in tetrahydrofuran ... 

Thus the molecular weight of polystyrene formed in the presence of ethanol is 400 times that formed in the presence of water. High polymer formation is more probable with ethanol impurity. 

The solvent should be inert and should ideally be able to dissolve the intermediates before the polymerization is started. A primary requisite for high polymer formation in all solution polycondensation reactions is that the solvent must be able to dissolve or swell the polymer sufficiently to permit the completion of the polymerization [75-77]. The solution polycondensation process requires a stronger polymer-solvent interaction than does the... 

For the case of dimethyldichlorosilane the following hydrolysis conditions favor high polymer formation ... 

The angle and bond deformations are most pronounced for the three- and four-membered cyclic monomers and as a result [M]eq is very small. The five- and six-membered cyclic monomers are the least strained, and some of them are unable to polymerize. The introduction of a carbonyl group into the five-membered cycle makes the resultant compounds incapable of high polymer formation under normal conditions. This is caused by sp hybridization of the carbon atom in the... 

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