The concentrated emulsion polymerization using nonionic polymerizable polyurethane (PUAG)/ styrene (St) as mixture monomers was studied. The effects of NCO/OH molar ratio, composite emulsifier concentration, different emulsifiers, initiator concentration, volume fraction of the monomer phase (Φ) and temperature on the polymerization stability and kinetics of the concentrated emulsion were investigated. The morphology of polymer particles, the average size and distribution of the latex particles were analyzed by transmission electron microscopy (TEM) and photon correlation spectroscopy (PCS), respectively. The conditions for polymerization with a higher stability, higher polymerization rate, small particle size and homogeneous particle size distribution were as follows: n(NCO)/n(OH)＝2∶1, T＝328 K, Φ＝80.39%, [I]＝0.8% g/g (PUAG-St), [E]＝0.22 g/mL H₂O, m(MS-1)/m(CA)＝2∶1, PVA＝0.01 g/mL H₂O. The apparent polymerization kinetics and activation energy were found to be R_p＝k [I]^0.50[E]^0.73[M]^0.54 and E_a＝29.7 kJ/mol, respectively. Thermogravimetry analysis (TGA) result indicates that the stability of polystyrene may be promoted by adding appropriate amount of PUAG.

Key words: concentrated emulsion polymerization, polymerization kinetics, polymerization stability, particle size, distribution