MANIPULATION OF COMPETITIVE GROWTH FOR PARTICLE-SIZE CONTROL IN EMULSION POLYMERIZATION

The utility of the growth mechanism to influence relative particle gro wth is investigated in a semi-batch reactor. A dynamic competitive gro wth model is developed and used to simulate the growth of two monodisp erse polystyrene particle populations !bidisperse system) at 50 degree s C. Validation of the model with on-line density and on-line particle diameter measurements demonstrates that radical absorption into parti cles is more likely to occur by a collision mechanism than either by a propagation or diffusion mechanism. Experimental and simulation resul ts show that relative narrowing of the bidisperse system increases as the weight fraction polymer inside the particles (W-p) decreases. It i s concluded that the ability to alter W-p in a semi-batch reactor make s this mode of operation attractive for particle size distribution con trol.