(a) The measured dependences of the pull-out load on the embedded length for both BNNT-PMMA and BNNT-epoxy interfaces. The dashed lines represent the respective linear fitting curves to the data sets whose embedded tube lengths are below or above the critical embedded length. (b) Comparison of the diameter-weighted IFSS and IFE for four types of nanotube-polymer interfaces. The values on CNT-PMMA and CNT-epoxy interfaces are calculated based on the data reported in Refs. 17 and 18, respectively. All quantities are normalized with respect to the values of BNNT-epoxy interfaces.