| abstract |
Improved process for the preparation of water-soluble substantially linear, high molecular weight polymers comprising irradiating an aqueous solution of an ethylenically unsaturated monomer and a chemical, free-radical initiator under conditions to cause radiation-induced polymerization of the monomer, terminating radiation of the system when less than all the monomer has been converted to polymer and when the temperature of the system is such that the chemical, free-radical initiator dissociates with the proper rate to sustain polymerization, and continuing the polymerization to completion by the free radicals generated by the thermal decomposition of the chemical initiator. The radiation-induced polymerization is terminated before more than 95% of the monomer is converted to polymer and preferably before 90% of the monomer is converted to polymer. The remaining monomer is converted to polymer by the free radicals generated by the thermal decomposition of the chemical initiator. Reaction conditions include: monomer concentrations from 10% to 60% by weight, radiation intensities of 1,000 to 1,000,000 rads per hour, and radiation dose from 1,000 to 150,000 rads. |