Enhanced mechanical and thermal properties of epoxy with hyperbranched polyester grafted perylene diimide

Abstract

A new kind of reactive toughening agent, named H20-g-PDI, has been successfully synthesized via hyperbranched polyester (H20) grafted to perylene diimide (PDI). The chemical structure of H20-g-PDI was characterized by Fourier transformed infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), wide angle X-ray diffractometry (WAXD), respectively. The H20-g-PDI was used as a toughening agent to enhance the mechanical and thermal properties of the epoxy resin. The morphology, mechanical and thermal properties of the composite was systematically investigated. The experimental results revealed that the impact strength, tensile strength, flexural strength and flexural modulus of the epoxy resin modified by H20-g-PDI reached the highest values of 47.6 KJ m⁻², 93.19 MPa, 128.8 MPa, and 2205 MPa, respectively. These were 81.33%, 68.1%, 62.0%, and 19.8% higher than the neat epoxy when the content of H20-g-PDI loading reached 1.5 wt%. In addition, the glass transition temperature (T_g) and thermal stability of the epoxy composite was also enhanced. T_g and the decomposition temperature (T_d) of the epoxy composite was about 20 °C and 27 °C higher than the neat epoxy, respectively. It is suggested that the formation of H20-g-PDI is effective to enhance the mechanical and thermal properties due to the homogeneous dispersion and strong interaction between the H20-g-PDI and the epoxy matrix.