Electron beam (EB) radiation was investigated as a means to initiate coupling between the fiberglass and plastic phases in fiberglass/polyethylene plastic composites using two bifunctional compounds, 12-azido-1-diazo-2-dodecanone (A) and 1-diazo-17-octadecene-2-one (B). Chemical studies reveal that EB radiation has the potential to bind both of these compounds to fiberglass. Fiberglass coated with either A or B shows reduced values of percentage recovery upon exposure to EB, indicating a reaction between these compounds and the glass surface. However, even 400 kGy of radiation was not as effective as a heat treatment for 45 min at 150degreesC. To test the effectiveness of EB radiation to couple these compounds to polyethylene, fiberglass samples were heat-treated with compounds A and B, followed by extrusion mixing with polyethylene, and exposure of molded tensile and impact samples to EB radiation. Compound B showed the best overall ability to couple with the polyethylene matrix, but a 400-kGy dose was necessary to bring about substantial coupling. At 400 kGy, samples containing B showed a 23% improvement in tensile properties and a 30% change in Izod impact.