In the esterification step of PET formation, we Investigated the effect of TPA particle sizes on the solubility and reactivity of TPA in EG to illuminate the mechanism of dissolution. The solubility was estimated by clear time and turbidity. The reactivity of TPA was determined by acid and saponification values. As the particle size of TPA decreased, both enhanced reactivity and solubility were introduced. The results suggest that small portion of TPA in EC is dissolved %rst the proton farmed in EG plays the role of an acid catalyst, then, the ester formed accelerates the dissolution and esterification of TPA.