Investigating the effects of γ-ray irradiation on the mechanical and dielectric properties of poly(lactide)/poly(butylene adipate-co-terephthalate)/carbon nanotubes composites

Poly(lactide)/poly(butylene adipate-co-terephthalate)/carbon nanotubes (PLA/PBAT/CNTs) composites with a fixed composition were prepared by melt blending without strict control of the pretreatment of CNTs. Then, gamma-ray irradiation was utilized to control microstructure, enhance component-interaction, and improve the performance of the prepared PLA/PBAT/CNTs composites, and the effects of different doses of gamma-ray irradiation on mechanical and dielectric properties of the composites were investigated. Mechanical test results reveal that the irradiated PLA/PBAT/CNTs composites exhibit much better mechanical properties than the unirradiated composites. Especially when the irradiation dose is 6 kGy, the tensile strength of the composites increases from 31.9 to 42.1 MPa; meanwhile, the elongation at break increases from 160 to 230%. Dielectric test results indicate that when the irradiation dose reaches 24 kGy, the dielectric constant of the composites is significantly enhanced and the dielectric loss is obviously decreased. The rheology tests reveal the irradiated PLA/PBAT/CNTs composites display a significant increase in the storage modulus compared to unirradiated composites, which suggests that the gamma-ray irradiation can induce the formation of crosslinking network in the polymer matrix; meanwhile, the interaction force between CNTs and polymer matrix is enhanced in the composites. The significant morphological changes observed in the SEM micrographs can be consistence with the rheology test results. This work provides a facile way for constructing high-performance PLA blend composites, which can be applied in electronic fields.