Abstract
In this study, alkali soluble resin (ASR) was evaluated as a surfactant in emulsion polymerization of SM, MMA, EMA, BMA, and BA, respectively. Batch reaction was used to evaluate the reaction behaviors. Kinetic analysis, surface tension and alkali separation methods were employed to study the reaction behaviors.The structure of ASR was determined by using 13C NMR and pyrolyzes GC and the ASR structure was (SM)0.34 (AMS)0.28 (AA)0.38. The critical aggregation concentration of neutralized ASR was broad from 1g/L to 9.3g/L by measuring the surface tension of ASR aqueous solution. The results were found that ASR can effectively stabilize the monomer such as MMA, EMA, BMA and SM. The ASR not only plays a stabilizer in the emulsion polymerization but also grafts onto the polymer to retard the reaction rate. The retarding effect of ASR was also observed in this reaction, which formed a barrier layer around the particle and depressed the radical number in the particle. The interval II, growth of polymer particles in the absence of micelles, does not exist in this system because the particle nucleation period lasts until the disappearance of the droplets. The power dependencies of particle number on the ASR concentration and the initiator concentration are 0.309 and 0.515, respectively. It reconfirms that the coagulative nucleation mechanism and the longer nucleation period do exist by using ASR as the surfactant.Kinetic analysis indicated that the saturated monomer concentration within particle and the particle size have dominant effects on the average radical number per particle. The decreases of particle size or the increases of monomer concentration within the particle enhance the radical diffuse into the continuous phase and reduce the average number of radicals per particle. The above results also indicate that the grafting reaction onto ASR is proportional to the concentration of ASR and initiator. But the water solubility of monomer is the major factor that affects the grafting reaction. Low water solubility monomers favor micellar nucleation and enhance the grafting reaction onto ASR.