Effect of electron beam irradiation on thermal stability and crystallization behavior of flexible copolyester/multiwalled carbon nanotubes nanocomposites

Poly(butylene adipate-co-terephthalate) (PBAT), a biodegradable copolyester, was used as the polymer matrix to prepare nanocomposites with multiwalled carbon nanotubes (MWCNT) by melt-mixing followed by hot-pressing. The PBAT/MWCNT nanocomposites were exposed to electron beam (EB) irradiation, and thermal stability, melting and crystallization behavior of irradiated and unirradiated nanocomposites were comparatively investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively. TGA results reveal increased thermal stability (up to 17?) and maximum degradation temperature (T-max) (up to 15?) of PBAT/MWCNT nanocomposites, attributed to the high thermal stability of MWCNT and good MWCNT-PBAT interfacial interactions. However, the activation energy for thermal degradation (E-a) decreased with the presence of MWCNT in comparison to neat PBAT regardless of the MWCNT concentration. Both the thermal stability and T-max of irradiated nanocomposites decreased by 3? despite the crosslinking which can be attributed to successive minor irradiation-induced polymer degradation, while E-a remained unchanged. Declined melting temperature (T-m), enthalpy of crystallization, enthalpy of melting and crystallinity of nanocomposites with the presence of MWCNT suggest the formation of less perfect crystals. Meanwhile, their increased glass transition temperature (T-g) and crystallization temperature (T-c) are due to the increased rigidity of PBAT chains and a reduced crystallization process in the presence of MWCNT, respectively. Similarly, reduced crystallinity and values of T-m and T-c of EB-irradiated nanocomposites by 4.1%, 9.6%, and 7.5%, respectively, signifying the presence of PBAT-crosslinks resulting in crystal defects.