Carbon Dioxide → HCID 19842620, compound

Participants

Reaction Steps

A 1.3-liter jacketed stirred reactor was used as the polymerization vessel. To the nitrogen blanketed reactor, 10 mL of cyclohexane was added by syringe to cover the dump valve depression. To ensure adequate mixing of the small volume materials for the first stage polymerization, the additions were done in the following manner. To a separate nitrogen-filled flask, 20 mL of cyclohexane, 12.7 mL of DFI solution (0.740 mmole DFI), and 12 mL of isoprene were added at room temperature and mixed with a magnetic stirring bar. This solution was immediately transferred from the flask to the reactor by syringe. Additional 25 mL of cyclohexane was used to rinse the flask and syringe to ensure complete transfer. A total of about 68 mL cyclohexane was used for the first stage of polymerization. The isoprene concentration was 0.03 moles/liter and the isoprene-to-DFI mole ratio was 162. The DFI concentration was 0.009 mole/liter. A nitrogen pressure of 8-14 psi (55.1 to 96.5 kPa) was maintained in the head space of the reactor during the entire polymerization. The temperature controller of the heating jacket was then changed from 25° C. to 55° C. The jacket temperature rose to about 70° C. in 7 minutes and dropped to 55° C. in 20 minutes. At this point, the first stage polymerization was considered completed. To begin the second polymerization stage, more cyclohexane (550 mL) was added from a 1-liter stainless steel vessel to the reactor through a quick connect and more isoprene (105 mL=71.5 g) was added by syringe. An exothermic temperature rise occurred immediately and peaked at 88° C. in 7 minutes. About 40 minutes after the beginning of the second polymerization stage, 15 mL of styrene was added by syringe. About 30 minutes after the addition of styrene, 1 mL of 2-propanol was added to terminate the polymerization. The polymer solids in the final syrup was about 16.2 percent w/w as calculated from material balance. The cooled polymer solution was discharged from the reactor, treated with CO2 and 1.5 grams of 2,6-ditertiarybutyl-4-methylphenol antioxidant was added. The polymer was recovered by vacuum devolatilization at an oven temperature of 190° C. for about 50 minutes. The polymer was analyzed and its properties tested. The results are compiled in Table I.

Provenance & Evidence