Thermal behavior and crystallization kinetics of random poly(ethylene-Co-2,2-bis[4-(ethylenoxy)-1,4-phenylene]propane terephthalate) copolyesters

The thermal behavior of poly(ethylene-co-2,2-bis[4-(ethylenoxy)-1,4-phenylene]propane terephthalate) (PET/BHEEBT) copolymers was investigated by thermogravimetric analysis and differential scanning calorimetry. A good thermal stability was found for all the samples. The thermal analysis carried out using DSC technique showed that the Tm of the copolymers decreased with increasing BHEEBT unit content, differently from Tg, which on the contrary increased. Wide-angle X-ray diffraction measurements permitted identifying the kind of crystalline structure of PET in all the semicrystalline samples. The multiple endotherms similar to PET were also evidenced in the PET/BHEEBT samples, due to melting and recrystallization processes. By applying the Hoffman–Weeks' method, the Tm° of PET and its copolymers was derived. The isothermal crystallization kinetics was analyzed according to Avrami's treatment and values of the exponent n close to 3 were obtained, independently of Tc and composition. Moreover, the introduction of BHEEBT units was found to decrease PET crystallization rate. Lastly, the presence of a crystal-amorphous interphase was evidenced. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1441–1454, 2005