The structure and properties of blends of poly(ethylene terephthalate) (PET) with poly(trimethylene terephthalate) (PTT) at PTT concentration <= 30 wt %, obtained with three different methods, from solution, melt extrusion, and direct spinning, are investigated Relationships between the method of preparation and properties of blends are established All blends show glass transition temperature at values determined by composition, and crystallization properties also dependent on the preparation method Blends obtained from solution show separated melting of components For blends obtained from the melt only PET crystallizes The melting temperature decreases with the residence time of the melt at high temperatures, due to occurrence of ester exchange reactions It is shown that reactive blending of PET/PTT mixtures occurring during preparation is a versatile route for obtainment of engineering materials with good mechanical properties, high crystallinity, glass transition temperature lower than that of PET, and melting temperature that may be controlled by the processing conditions (C) 2010 Elsevier Ltd All rights reserved