Effect of nanoparticles on mode‐I fracture toughness of polyurethane foams

Abstract

AbstractMode‐I fracture toughness of rigid polyurethane (PUR) foam modified with nanosize particles of different shapes and sizes have been examined using a single edge notched bend (SENB) specimen under three‐point bending configuration. The PUR foams with density of 260 kg/m3 and four different types of nanoparticles, namely, nano TiO2 (5, 10, and 35 nm), nanoclay, carbon nanofibers (CNFs), and multiwall carbon nanotubes (MWNTs) are considered. Nanophased PUR foams are prepared through the infusion of nanoparticles into liquid PUR foam precursor in the range of 0.5–2 wt% with 0.5‐wt% increment using a sonochemical method. The linear elastic fracture mechanics (LEFM) model has been used to determine the mode‐I fracture toughness. The fracture toughness data have been validated with the plain strain fracture criteria and found to be appropriate. It is observed that the infusion of CNF at 0.5‐wt% loading shows the highest enhancement in fracture toughness (about 28%) over neat counter part. Among different sized nano TiO2, 5 nm nanoparticles show the highest improvement (about 16%) at a doping of 1.0 wt%. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers