Research On NEAS Based On Single-walled Carbon Nanotubes

NEAS has a much higher energy absorption density than conventional materials and it is reusable,therefore,it is promising in the damping and protection field.Single-walled carbon nanotube(SWNT)with large specific surface area can be used as the nanoporous media in NEAS.After being cut,the single-walled carbon nanotubes have suspended bonds and need to combine functional groups to maintain the stable structure.Meanwhile,the functional groups change the flow characteristics in the port.Molecular dynamics simulation is undertaken to study the effect of hydrophilic functional groups added to the port or inner wall of the single-walled carbon nanotubes on the infiltration pressure and behavior of water under quasi-static situation.The infiltration pressure of water infiltration from different modified ports is calculated as the SWNT port is added with different numbers of carboxyls and hydrogen atoms.The SWNT-H has the lowest infiltration pressure,as the number of carboxyl increases,the infiltration pressure rises.Furthermore,the influence of those short carbonyl and hydroxyl groups is investigated,both of them hinder water infiltration to raise the infiltration pressure.Oxygen-containing groups are added to the inner walled of SWNT to study the effect of functional groups on water infiltration.The increase of number of carboxyl,carbonyl or hydroxyl groups leads to the rise of the water infiltration pressure and the carboxyl groups are most obstructive because of its longest chain length.The farther the carbonyls are from the port,the greater the infiltration pressure of water molecules into the tube is.Oxygen-containing groups are added to the port or inner wall of SWNT to study the effect of functional groups on water exfiltration.Five or more carboxyls at the port favor the exfiltration of water while carbonyls or hydroxyls do not.Groups on the inner wall hinder water exfiltration,NEAS is reusable only when two carbonyls exist.The NEAS based on SWNT-HxCOOH has an single energy absorption density up to 10 J/g.NEAS that can be recycled has an energy absorption density of up to 20 J/g during its life cycle.