| 摘要 |
1312633 Bulk polymerization of dienes FIRESTONE TIRE & RUBBER CO 21 Aug 1970 [22 Sept 1969] 40494/70 Heading C3P Conjugated dienes are polymerized or copolymerized in bulk, using an organolithium initiator, by a procedure in which the heat of reaction is removed by evaporation and condensation of a controlled amount of the monomer and excessive foaming is avoided by keeping the temperature below the "critical minimum foaming temperature" until the solids content of the mixture exceeds the "critical polymer concentration" and then raising it to 50-150‹ C. to complete the process. The temperature at which excessive foaming occurs is found to vary with the solids content of the mixture, as illustrated, and to pass through a minimum, referred to as the "critical minimum foaming temperature" (usually about 40‹ C. for butadiene polymerization), the corresponding solids content being referred to as the "critical polymer concentration" and lying in the range 20-40%. These quantities are constants for a given set of reaction parameters. After the "critical polymer concentration" has been exceeded monomer may be introduced and polymer withdrawn continuously at the higher temperature while maintaining the polymer concentration above the critical value. |
