TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The epoxy resin is any one of polyglycidyl ether of a polyhydric alcohol or polyhydric phenol, and/or a novolak of formaldehyde and a phenol or a cresol. The hardener is an amine hardener comprising polyetheramine, cycloaliphatic amines having an amino or aminoalkyl group attached to the ring, an amino polyamide, and/or tetraethylenepentamine, or a mixture of polyetheramine, isophoronediamine and amino polyamide. The structural adhesive further comprises: 0.005-5 wt/wt.% a polyethyleneimine having a molecular weight of 100-1000000 Da; and up to 40 wt/wt.% milled fiber. The epoxy resin formulation comprises 50-99 wt/wt.% of the epoxy resin, 0.1-6 wt/wt.% of the treated silica and 0.1-10 wt/wt.% of the untreated silica, and further comprises up to 25 wt/wt.% a reactive diluent and up to 50 wt/wt.% of milled fiber. The hardener formulation comprises 60-99 wt/wt.% hardener and 0.1-15 wt/wt.% treated silica, further comprises 0.1-20 wt/wt.% of untreated silica, comprises 0.1-10 wt/wt.% of polyethyleneimine, and further comprises up to 40 wt/wt.% milled glass fiber. The epoxy resin formulation and the hardener formulation have a viscosity of 10-200 Pa.s. EXAMPLE - Epoxy resin formulation component was prepared using 70.74 pts. wt. of liquid diglycidyl ether of bisphenol A and 3.72 pts. wt. of glycidyl ether of 10C alcohols under vigorous stirring at 25 degrees C. Then, 19.36 pts. wt. of milled glass fiber, 4.69 pts. wt. of untreated fumed silica, and 1.49 pts. wt. of treated fumed silica were added into the resin component, and continuously mixed at 25 degrees C. Hardener formulation was prepared by dissolving 0.78 pts. wt. of polyethyleneimine in 8.29 pts. wt. of isophoronediamine under vigorous stirring at 60 degrees C until it was totally dissolved. Then, 60.85 pts. wt. of polyetheramine and 8.37 pts. wt. of polyamide were added, and mixed at 60 degrees C for 10 minutes. Then, 12.02 pts. wt. of milled glass fiber and 9.69 pts. wt. of treated fumed silica were added, and continuously mixed at room temperature. The epoxy resin formulation and hardener formulation were mixed at 25 degrees C in a weight mixing ratio of 100:42 to obtain the structural adhesive.