Effect of CTBN liquid rubber and flexible diamine curing agent on epoxy/glass prepregs properties

Glass/epoxy prepregs are widely used in composite industry. Although they have significant advantages, the brittleness nature of its epoxy matrix produces some difficulties. In this paper the effect of liquid carboxyl-terminated butadiene-acrylonitrile rubber (CTBN) and a flexible diamine (Jeffamine D-400) curing agent on epoxy prepregs based on diglycidyl ether of bisphenol-A (DGEBA) resin and dicyandiamide (Dicy) reinforced with glass fiber were studied. For this purpose, after preparing the resin formulation and its impregnation with glass fiber or preparing the prepreg samples, the effect of CTBN and Jeffamine on epoxy/glass prepregs properties like resin flow, lap shear strength (LSS) and interlaminar shear strength (ILSS) were studied. Volatile content, resin content and pre-curing of prepared prepregs are characterized. Results show that in all samples the amount of resin content, volatile content and pre-curing were nearly the same and adding different amounts of CTBN or Jeffamine do not changed the resin flow. By adding 20 phr of liquid rubber, LSS does not changed but, adding the Jeffamine up to 20% increased the LSS by 8% and adding Jeffamine up to 40% does not changed this property. By adding the CTBN by 5 phr, the ILSS increased by 7.7% and in all Jeffamine samples the ILSS varied from 4.6 MPa for 100% Dicy to 2.0 MPa for sample containing 60% of Jeffamine and 2.6 MPa for 100% of Jeffamine content.