Clever use of PCL as kinetic controller in PBT/PCL blends

This work investigated the melting and nonisothermal melt crystallization of poly (butylene terephthalate) (PBT) and poly (epsilon-caprolactone) (PCL) blends with PCL content ranging from 3 to 10% of the weight. Thermal stability and morphology analyses were performed by thermogravimetry (TG) and scanning electron microscopy (SEM), whereas the nonisothermal crystallization of PBT/PCL blends carried out by differential scanning calorimetry (DSC), and the kinetic parameters were determined using Pseudo-Avrami, Ozawa and Mo models. PCL improved thermal stability by decreasing the degradation rate of PBT. From SEM images the brittle fracture of PBT was modified through PCL addition with absorption energy mechanisms developed in PBT/PCL blends. PCL delayed the melt crystallization of PBT, most due to its fluid viscous state during PBT crystallization. Ozawa model failed to provide an effective description of the blends, while Pseudo-Avrami and Mo models successfully described the nonisothermal melt crystallization, and linearity deviations were observed only at the beginning and at the end of crystallization, probably due to nucleation and spherulite impingement during secondary crystallization.