Introducing a nano-scale surface morphology parameter affecting fracture properties of CNT nanocomposites

Carbon Nanotube (CNT) particles and membranes improve interlaminar fracture toughness of nanocomposites. The novelty of this study is to introduce the effect of a new nanoscale parameter - CNT network (bundle) size to interphase thickness ratio - on modes I and II interlaminar fracture toughness of CNT Polymer Nanocomposites (PNCs). This investigation includes the stochastic distribution function of CNT bundle size, interphase thickness, and modes I and II fracture toughness of PNCs based on an extensive experimental study at the nanoand macroscales. The Atomic Force Microscopy PeakForce Quantitative Nanomechanics Mapping technique was used to collect 500 datasets for a low-weight percentage of CNT PNC and 180 datasets for a high-weight percentage of CNT PNC. Each dataset included CNT bundle size and interphase thickness at the nanoscale. Double cantilever beam and end-notched flexure experiments were conducted to collect 600 modes I and II fracture toughness data. Two-, three-, and four-parameter Weibull models were used to simulate the nanoand macro-scale material properties of CNT PNCs. Results indicate that (i) a lower CNT bundle size to interphase thickness ratio improves fracture toughness, and (ii) a four-parameter Weibull model is the most efficient model for simulated data.