Tham khảo tài liệu 'nanofibers part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 320 Nanofibers strain analysis showed that the tensile strength of SWNT reinforced polyurethane PU nanofibre membrane was enhanced by 46 compared to pure PU nanofibre mat 119 . However this value was further increased by 104 for PU membranes containing ester-functionalized SWNTs. This improvement in the mechanical strength was attributed to improved dispersion of the SWNTs as well as enhanced interfacial interaction of nanotubes with the PU matrix because of modified nanotube surface 119 . Recently Yoon et al. 150 reported enhancement in mechanical strength of CNT reinforced nanofibres caused by better nanotube-polymer adhesion and good dispersion of SWNT because of the plasma treatment of nanotubes. Uniform dispersion of amino functionalised MWNTs and nanotube alignment in nylon 6 led to increased mechanical properties of electrospun MWNT nylon-6 nanofibre mat 137 151 . The upper limit of CNT concentration in electrospun nanofibres is also confined by the extent of CNT dispersion. Hou et al. 113 reported thick sheets of electrospun PAN nanofibres containing well-aligned MWNTs with concentrations from 0 to 35 wt . It was shown that the presence of MWNTs improved the modulus and tensile strength of the composite nanofibre sheet. The tensile modulus increased with increasing the concentration of MWNTs in nanofibres. However the tensile strength of nanofibres increased with an increase in the concentration of MWNTs up to 5wt and then started to reduce for higher MWNTs content. This was attributed to poor dispersion of the MWNTs and poor interfacial cohesion between the MWNTs and the polymer matrix at higher concentrations. Meanwhile strain to break reduced with increasing the MWNT concentration. Similar findings have also been reported by other research groups 152 153 . The importance of fibre alignment on the mechanical properties has been well established. In a study by Jeong et al. 154 aligned electrospun MWNT PVA membranes have been reported. The tensile strength
