Abstract
The present work investigates the mechanical properties of conventional and hybrid composites based on epoxy resin. Diglycidyl ether of bisphenol A was used as the matrix and triethylenetetramine was used as the curing agent. Polyurethane (PUR) used was based on polyether and toluene diisocyanate. Impact strength (IS), critical stress intensity factor (Kc), tensile strength (TS) and flexural strength were evaluated as function of modifiers content. It is shown that IS is increased by approximately 120% and 200% with the addition of respectively 10 phr of glass beads (GB) or 10 phr PUR, in comparison with IS of the unmodified epoxy resin. Moreover, Kc was increased by approximately 20% with 10 phr GB and 35% with 10 phr PUR. The addition of 15 phr PUR gave compositions with 30% enhanced TS and 40% increased tensile strain at break. However, the strain at break decreased with increasing amount of GB. Hybrid composition containing 10 phr PUR and 15 phr GB exhibited the maximum tensile energy to break corresponding to 80% and 85% improvement respectively in relation to the energy at break of the virgin epoxy resin and composition with only 10 phr PUR. Infrared spectra analysis of the compositions containing PUR revealed the formation of an interpenetrating polymer network structure between the modifier and the polymer matrix