Effects of thermoplastic preforming binder on the properties of S2-glass fabric reinforced epoxy composites

The effect of a thermoplastic polyester binder on the thermophysical and me chanical properties of an S2-glass/epoxy-amine system was investigated. The purpose of the polymeric binder is to bond the individual fabric layers to gether during preforming prior to composite fabrication. This paper will ad dress the significance of the binder chemistry. i.e., the compatibility of the binder with the matrix polymer. on the composite properties. The peel s trength of preforms consolidated with various concentrations of binder was evaluated using the T-peel test. The highest peel resistance was obtained f rom preforms that have full coverage of the binder on the glass fabric. Fur ther increase of the concentration of the binder does not change the peel s trength. Scanning electron microscopy (SEM) on peel test fracture surfaces revealed mostly adhesive-type failure between binder and fiber. Double cant ilever beam (DCB) and short beam shear (SBS) test results of the composite showed that the presence of about 2.6 wt% of the polyester binder reduces t he Mode I interlaminar fracture toughness and apparent interlaminar shear s trength of the S2-glass/SC-15 epoxy-amine system by about 60% and 25%, resp ectively. Moreover, the T-g of the matrix polymer within the interlaminar r egion decreases about 6 degreesC due to the presence of the binder. The dis solution of the polyester binder within the reacting matrix resin is limite d for the standard cure cycle. (C) 2001 Elsevier Science Ltd. All rights re served.