On the modelling of continuous emulsion polymerization using a population balance with instantaneous radical termination
✍ Scribed by D.A. Cauley; A.J. Giglio; R.W. Thompson
- Publisher
- Elsevier Science
- Year
- 1978
- Tongue
- English
- Weight
- 610 KB
- Volume
- 33
- Category
- Article
- ISSN
- 0009-2509
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✦ Synopsis
An analyttcat solution of a population baIance IS used to mathematlcalfy descnbe continuous emulsion polymenzatlon Steady state performance 1s examined The assumption of mstantaneous free raduxl termmatlon wIthin particles IS made The desorptlon mechamsm IS mcluded Particle sue dtstnbution mformatron IS obtamed, and the effect of the desorvtlon mechamsm IS noted A desorptlon rate constant IS calculated when the model IS fit to dah found m the hteratke INTkmDucTlCM Although the commercial Importance of emulsion polymenzatlon IS widely recogmzed, the complex kmetlcs mvolved are not fully agreed upon In 1945 Harkms[ I] ldentdied the roles of the water, emulsdier, mltlator and monomer components of the reactmg system The water phase was considered the solvent for the free radical mltiator The actual polymenzatron was thought to occur m discrete particles, stabdlzed by the emulsifier, m the water phase The quahtatlve aspects of his proposed scheme are generally accepted with mmor changes due to recent advances m the field Smith and Ewart[2] developed a mathematical description of Ha&m's concept of emulsion polymenzatlon mechamsms Thev steady-state recursion formula accounted for the transfer of free radicals between the water phase and the polymer par@les Theu model consldered absorptton, desorptlon and mutual termmatlon of the free radicals within the particles It was assumed that all particles were of the same size and that the particles grew at a constant and umform rate Smith and Ewart solved their recurslon formula for several hmltmg cases, the most sigmficant of which was when the rate of mutual termmatlon of free radicals within a polymer parttcle was assumed to be mfirutely fast relative to the absorption of free radicals A consequence of thrs assumption was that the average number of free radicals per polymer particle, if,, was 0 5 Th case Implies that a polymer particle can house only one free radical at a time A second entermg radical would mstantaneously termmate with the first More recent thmkmg has consldered the posslblllty of havmg more than one free radical, I e growmg chams, housed m a polymer particle at a given *me Stockmayer[3] was able to analytically solve a radlcalparticle balance Using a generating funcuon, he converted the Smith-Ewart recursion formula to an ordmary d@erentlai equation HIS solution for & took the form of a ratio of modified Bessel functions *Present address Umroyal Chem ,