2008 Volume 41 Issue 9 Pages 845-854
The effect of shear rate on heteroaggregation behavior of latex polymers and suspension polymers in aqueous media was investigated. Heteroaggregation was carried out in a stirred vessel under various stirring rates and temperatures. Large suspension polymer particles were selectively coated by small latex polymer particles at specific stirring rates corresponding to each temperature. The heteroaggregation dynamics were analyzed from the cluster strength of the coating latex polymer layer and external shear force. The cluster strength of the latex polymer was determined by using Usui’s rheology model, where the inter-particle bonding energy was derived from both the rheological data and the rate of energy dissipation per unit mass in the stirred vessel. In contrast, a relation between the diameter of the cluster of the latex polymer particles and apparent shear rate was derived from Kobayashi’s theory, which is based on the theoretical treatment on the break-up of a droplet. By combining both theories, the heteroaggregation process was characterized by the cluster strength of the latex polymer layer against the external shear force. The homogeneous coating was only formed in a specific condition where the favorable balance between the external shear force and the cluster strength of the latex polymer layer was achieved.