arXiv subjects

Chenyu Wei

Publications and source records attributed to Chenyu Wei.

3 recordsLinked to original sources

arXiv2006

Radius and chirality dependent conformation of polymer molecule at nanotube interface

Temperature dependent conformations of linear polymer molecules adsorbed at carbon nanotube (CNT) interfaces are investigated through molecule dynamics simulations. Model polyethylene (PE) molecules are shown to have selective conformations on CNT surface, controlled by atomic structures of CNT lattice and geometric coiling energy. PE molecules form entropy driven assembly domains, and their preferred wrapping angles around large radius CNT (40, 40) reflect the molecule configurations with energy minimums on a graphite plane. While PE molecules prefer wrapping on small radius armchair CNT (5, 5) predominantly at low temperatures, their configurations are shifted to larger wrapping angle ones on a similar radius zigzag CNT (10, 0). A nematic transformation around 280 K is identified through Landau-deGennes theory, with molecule aligning along tube axis in extended conformations

cond-mat.mtrl-sci↗

arXiv2002

Thermal Expansion and Diffusion Coefficients of Carbon Nanotube-Polymer Composites

Classical molecular dynamics (MD) simulations employing Brenner potential for intra-nanotube interactions and Van der Waals forces for polymer-nanotube interfaces are used to invetigate the thermal expansion and diffusion characteristics of carbon nanotube-polyethylene composites. Additions of carbon nanotubes to polymer matrix are found to increase the glass transition temperature Tg, and thermal expansion and diffusion coefficients in the composite above Tg. These findings could have implications in CNT composite processing, coating and painting applications.

cond-mat.mtrl-sci↗

arXiv2002

Tensile Strength of Carbon Nanotubes under Realistic Temperature and Strain Rate

Strain rate and temperature dependence of the tensile strength of single-walled carbon nanotubes has been investigated with molecular dynamics simulations. The tensile failure or yield strain is found to be strongly dependent on the temperature and strain rate. A transition state theory based predictive model is developed for the tensile failure of nanotubes. Based on the parameters fitted from high-strain rate and temperature dependent molecular dynamics simulations, the model predicts that a defect free $μm$ long single-wall nanotub at 300K, stretched with a strain rate of $1%/hour$, fails at about $9 \pm 1%$ tensile strain. This is in good agreement with recent experimental findings.

cond-mat↗