**2.1.3 Plasticizer uptake by polymer**

The rate of plasticizer uptake is depended on the type and concentration of the plasticizer and the type of polymer dispersion, and also on the water solubility of the plasticizer. The plasticization time had a minimal effect on the rate of uptake of water-soluble plasticizers, while it had a strong effect on the uptake of water-insoluble plasticizers. Depending on plasticizer water-solubility and the added amount, when a plasticizer is added to an aqueous polymer dispersion, it is first dissolved and/or dispersed within the outer water phase. Subsequently, the plasticizer diffuses into the polymer particles. A sufficient amount of time for plasticizer uptake by the polymer particles is necessary to avoid forming an inhomogeneous plasticized system (Bodmeier Paeratakul, 1997).
