Synthesis of an alkynyl- and allyla- terminated modifiers and its thermal and mechanical properties in copolymer with epoxy resin

In this work, this study aimed to overcome the inherent disadvantage of low thermal stability and brittleness of epoxy resins. A novel modifiers containing alkynyl- and allyla- groups, (E)-1-(4-(allyloxy)-3-methoxyphenyl)-N-(3-ethynylphenyl)methanimine (MNEM) was prepared and confirmed by Fourier transform infrared spectroscopy (FTIR) and 1H-nuclear magnetic resonance (1H NMR), and selected to improve the thermal stability and toughness of bisphenol A-type epoxy resin (E51). The blend resins were produced by blending with different contents of MNEM into E51 resin, named E-MNEM resins. Meanwhile, the thermal stability, mechanical properties, and micromorphology of E-MNEM blends were analyzed in details. It was found that the thermal stability of E-MNEM resins was improved by increasing the proportion of MNEM. Compared with E-0MNEM resin, when the MNEM concentration reached 40 wt%, the char yield (Yc) increased from 14.95 to 29.62%, reflecting a 98.1% improvement. In addition, an appropriate concentration of MNEM could be conductive to improving the mechanical properties. An improvement of 25.5 and 7.1% in elongation and tensile strength along with the maximum value of 17.6 kJ/m2 for the impact strength was achieved by the cured E-MNEM resins containing 20 wt% of MNEM. Finally, the fracture surface morphology of the E-MNEM resins was analyzed by the scanning electron microscope (SEM).