TOUGHNESS IMPROVEMENT OF TETRAFUNCTIONAL EPOXY-RESIN BY USING HYDROLYZED POLY(ETHER IMIDE)

Toughened epoxy resins were prepared by dissolving poly(ether imide) ( PEI) in the EPON HPT 1071 based resin with EPON HPT 1061M as a curing agent. Open tension tests showed an increase in fracture toughness wit h PEI content, from 0.61 GPa m(1/2) in the pristine resin to 1.32 GPa m(1/2) at 15 wt% PEI. Similar results were obtained for the flexural p roperties of the epoxy resin. In order to improve the fracture toughne ss of epoxy resins, increasing the interfacial adhesion strength betwe en the dispersed PEI phase and tetrafunctional epoxy resin was necessa ry. Improved interfacial adhesion of the modified epoxy resin was obta ined through the hydrolysis of PEI. At a concentration of 5 wt% PET, h ydrolysed PEI/epoxy resin had 40% more fracture toughness than the unh ydrolysed PEI/epoxy resin. The effect of PEI hydrolysis on the flexura l properties of the cured epoxy resins was also studied. Scanning elec tron microscopy was used to investigate the relationship between the m orphological study of the fractured epoxy resins and mechanical proper ties of the modified epoxy resins.