Preparation And Properties Of Carbon Nanotubes/Polyvinyl Alcohol Composite Films

Carbon nanotube?CNTs?films have a wide range of applications due to their excellent mechanical properties,electrical properties and thermal conductivity,such as hydrogen storage materials,catalyst supports,fillers for composite materials and biological and pharmaceutical fields.At present,the theory strength of single carbon nanotubes was 50-200 GPa,the exploration of CNTs film still had a lot of space.It was a research hotspot to combine CNTs composites with reinforced polymers to improve the strength of CNTs film.In recent years,many aspects have been studied on the mechanical properties of CNTs/polymer composites.Increasing the uniform dispersion of CNTs and increasing the interaction of CNTs with polymeric chains were a major problem to improve the mechanical properties of composites.In this paper,polyvinyl alcohol?PVA?and network CNTs film were composited to prepare a uniform and stretchable CNTs/PVA composite film,the composite film was tested for mechanical properties,electrical properties and humidity response.The main experimental contents and conclusions were as follows:CNTs films were prepared by chemical vapor deposition method,and different concentrations?0.5 wt%,1 wt%,2 wt%and 4 wt%?of CNTs/PVA composite films were prepared by dip-rolling method.PVA had good biodegradability,high strength and high toughness,and dimethyl sulfoxide?DMSO?was a polar solvent with a large surface tension that can wet hydrophobic carbon nanotubes while allowing the PVA/DMSO solution to penetrate and remain in the gap between the bundles of CNTs tubes.This experiment mainly used PVA/DMSO solution as a composite solution.to solve the problem that the long-chain molecules of PVA were difficult to penetrate into the gap of the carbon nanotube bundle.The mechanical properties and electrical properties of composite film with different PVA content were tested.The tensile strengths of the composite film with PVA concentrations of 0.5 wt%,1 wt%,2 wt%,and 4 wt%were 418 MPa,415 MPa,561 MPa,and 127 MPa,respectively.The experimental results show that the composite film with PVA concentration of 2 wt%had the highest tensile strength,and the tensile strength of the composite films can reach 1 GPa after heat treatment at200°C.The strain increased and the conductivity decreased with the increasing of PVA content of the composite film.The conductivity of the composite film with PVA concentration of 0.5 wt%was highest(305.53 Scm^-1).Since the PVA in the composite film contained a large amount of hydrophilic hydroxyl groups,the humidity response test was carried out on the composite film with PVA concentration of 2 wt%,and the relative resistance change of the composite film could reach 8%.