| 초록 |
Three types of polyurethane resins (PURs) had been prepared from poly(1,2-propylene glycols) (PPG-750), 2,2-bis(hydroxymethyl)propionic acid (DMPA), and three types of diisocyanated material as followed isophorone diisocyanate (IPDI), 4,4-methylenebis (phenyl isocyanate) (MDI), and 4,4-methylenebis (cyclohexyl isocynate) (H12MDI). The effect of each PURs as emulsifier on kinetics of PS emulsion polymerization was investigated by the rate of polymerization, the particle size distribution, the number of particles, and the average number of radicals per particle. These polyurethane resins have similar acid number ( ca. 60 mg KOH/g PU) and molecular weight (Mn 2806~3220 g/mol). The polystyrene (PS) latexes prepared using PURs showed small particle size and colloidal stability. In the kinetics study, it was found that the rate of PS emulsion polymerization using PU-MDI showed slower than those of PS emuslion polymeirzation using the other PURs. This could be explained by larger size of aggregate due to rigid hard segment of PU-MDI in the aqueous phase and chain transfer effect of phenyl group located on MDI.
|
