(a) Schematic of a DWNT on a flat substrate partially covered by a thin membrane. (b) Schematics of the cross-sections of a DWNT (left) and a membrane-covered DWNT (right) on a flat substrate. (c) Free-body diagram of one-half of the covering membrane with the consideration of the adhesion interactions of the membrane with the nanotube and the substrate. The dotted curve represents one-half of the tube cross-section. (d) Simplified free-body diagram of the covering membrane segment AB with the lumped loads at its ends.
(a) Representative HRTEM image of one DWCNT (left) and AFM image of one MGOS-covered DWCNT (right). (b) Representative HRTEM image of one DWBNNT (left) and AFM image of one MGOS-covered DWBNNT (right). (c) and (d) The measured tube height in the vicinity of the covering membrane edge for the MGOS-covered tubes shown in (a) and (b), respectively. The horizontal axis represents the position along the nanotube axis. (e) and (f) Comparison of the respective cross-section profiles of the uncovered portion (dark green curve) and the MGOS-covered portion (dark red curve) of the tubes shown in (a) and (b), respectively. The profiles are plotted based on the measured height data marked in the green and red boxes shown in the AFM images in (a) and (b). The blue-color fitting curves are plotted based on Eq. (5) for the respective profiles in dark red.
(a) The respective dependences of the measured cross-section height reduction for MGOS-covered DWCNTs and DWBNNTs on the nanotube outer diameter. (b) Experimentally measured MGOS spanning length L.
The dependences of the calculated per-unit-length compressive load applied on DWCNTs and DWBNNTs on the nanotube outer diameter. The solid circles and squares represent results obtained based on Eq. (1), while the empty circles and squares represent results obtained based on Eq. (7).
Comparison between the calculated effective radial modulus data for DWCNTs (solid circles) and DWBNNTs (solid squares) based on Eq. (8) with those data reported in the literature. The DWBNNT data represented by empty squares are reproduced from Ref. 21; while from Ref. 46 for the DWCNT data represented by empty circles.
The respective dependences of the MGOS covering induced actual nanotube radial strain on the nanotube outer diameters for both single- and double-walled CNTs and BNNTs. The data for SWCNTs and SWBNNTs are reproduced from Ref. 24. The solid lines are the linear-fitting curves of the respective data sets.
List of the key experimentally measured and calculated parameters in the nanotube flattening measurements for six selected MGOS-covered CNT and BNNT samples.
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