Poly(butylene terephthalate)/poly(ethylene glycol) blends with compatibilizers

Polymer blend systems offer a versatile approach for tailoring the properties of polymer materials for specific applications. In this study, we investigated the compatibility of polybutylene terephthalate (PBT) and poly(ethylene glycol) (PEG) blends processed using a twin-screw extruder, with the aim of enhancing their compatibility. Phthalic anhydride (PAn) and phthalic acid (PAc) were used as potential compatibilizers at different concentrations to improve interfacial interactions between PBT and PEG. Blend morphologies were characterized using scanning electron microscopy, which revealed improved interfacial compatibility and reduced phase separation with the incorporation of small amounts of PAn and PAc. Differential scanning calorimetry analysis indicated changes in the melting temperature (T_m) and glass transition temperature (T_g) of the blends owing to the compatibilizing effects of PAn and PAc. Dynamic mechanical analysis further corroborated the influence of the compatibilizers on the T_g and viscoelastic behavior. Thermogravimetric analysis demonstrated enhanced thermal stability with the addition of either PAn or PAc. Rheological measurements indicated an increase in complex viscosity with increasing compatibilizer content, indicating improved compatibility. The degradation point (T_d) of PBT/PEG blend increased from 158 to 200 and 319°C with the incorporation of 5 phr PAn and 2 phr PAc, respectively. Mechanical properties, including tensile strength, Young's modulus, and Izod impact strength, were evaluated. For instance, the tensile strength of PBT/PEG blend was enhanced from 43.5 to 48.7 and 49.7 MPa by incorporating 5 phr PAn and 2 phr PAc, respectively. However, the impact strength of PBT/PEG blend increased from 3.0 to 4.3 and 4.2 kJ/m² with the addition of 1 phr PAn and 1 phr PAc, respectively. The findings demonstrated that adding 5 phr PAn or 2 phr PAc to the PBT/PEG blends was advantageous, achieving a harmony of performance benefits and compromises. Rheological observations contributed significantly to the mechanical and thermal properties. Overall, the study highlights the significance of utilizing PAn and PAc as effective compatibilizers for enhancing the properties of PBT/PEG blends, making them potential candidates for various applications.