1-Propanol, shortstop effect

Data Showing 1-Propanol Shortstop Effect Polymers 5, 14 and 15... 

Since 1-propanol is monofunctional and reacts with "matched dissociation isocyanate" (at internal urethane chain positions) as well as "unmatched isocyanate" (at polymer chain terminal positions) its effects include cleavage of some polyurethane chains in the process of generating more urethane groups. As a result, polymer DP, melt viscosity, and torque drop until the shortstop is consumed, or escapes the mixture by volatilizaton. Figure 9 shovjs that the more 1-propanol used to shortstop the polymerizations, the more pronounced the polymer reversion was. 

The data of Table X indicate the pronounced effectiveness of 1-propanol as a urethane polymerization shortstop. It does its job in about 1 to 2 minutes under the conditions investigated and DSV and T values decrease with increasing shortstop concentration. 

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See also in sourсe #XX -- [ ]

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