| Popis: |
Course and kinetics of the isothermal bulk polymerization of diallyl fumarate and the course of the polymerization of diallyl fumarate, diallyl maleate, and diallyl succinate by programmed heating were studied. 2,2′-Azoisobutyronitrile was used as initiator. The isothermal bulk polymerization was investigated at temperatures between 75 and 96°C and initiator concentrations ranging from 22,5 to 62,5 mmol/dm3 were applied. The bulk polymerization by programmed heating was investigated at temperatures between 40 and 190°C and at constant initiator concentration of 62,5 mmol/dm3. The negative value of the heat of isothermal bulk polymerization of diallyl fumarate at 75°C at the initiator concentration of 22,5 mmol/dm3 was found to be −63,6 kJ/mol and to increase with increasing temperature to −87,9 kJ/mol at 96°C. Also an increase was observed at higher initiator concentrations in the same temperature range. The initial rate constants for the isothermal bulk polymerization of diallyl fumarate were determined and from them the overall activation energy (100,4 kJ mol). It was found that the overall rate of polymerization at low degrees of conversion depends on the square root of the initiator concentration. The heats of the polymerization by programmed heating at constant initiator concentrations for diallyl fumarate, diallyl maleate, and diallyl succinate were found to be −126,4, −82,9, and −90,8 kJ/mol, respectively. In all cases the DSC-curves display two peaks. On the basis of the results obtained, it was possible to interpret the differences in reactivity of individual functional groups in these compounds observed in programmed heating. |
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