(142ak) The Effect of Filler and Diamine Size on the Fracture Toughness of Alumina Reinforced Epoxy Composites | AIChE

(142ak) The Effect of Filler and Diamine Size on the Fracture Toughness of Alumina Reinforced Epoxy Composites

Authors 

McGrath, L. M. - Presenter, University of Connecticut
Lenhart, J. - Presenter, US Army Research Laboratory
King, S. H. - Presenter, Sandia National Laboratories


The stress intensity factor, KIc, was used to quantify the fracture toughness of novel epoxy alumina (Al2O3) reinforced composites based on bisphenol A diglycidyl ether (DGEBA) and diamines with a poly(propylene oxide) (PPO) backbone. Such epoxy composites are very useful in industry due to their excellent mechanical properties and chemical resistance. However, their brittleness often leads to crack propagation and specimen failure. Herein we present the effect of the variation of the particle size diameters (2, 5, 10, 18 and 26 μm), particle size distribution and inter-crosslink distance (PPO spacer lengths of Mn = 230, 400 and 2000) on the fracture toughness. The KIc increased with an increase in Al2O3 volume fraction for all particle sizes and distributions tested and typically doubled at 50% (v/v) Al2O3. With the exception of DGEBA-230/18μm-Al2O3, the larger PPO spacers resulted in higher fracture toughness of the unfilled epoxy but decreased the incremental toughening effect of the Al2O3. The particle sizes did not affect the KIc values. An unexpected, 6-fold increase in KIc at 50% Al2O3 (v/v) was achieved with the DGEBA-230/18μm-Al2O3 system. This promising work increases current understanding of particle and matrix variables.