A comparative sutdy of melt spun polyamide-12 fibres reinforced with carbon nanotubes and nanofibres

摘要

Arange of multi-wal carbon nanotubes and carbon nanofibres were mixed with a polymaide-12 matrix usign a twin-screw microextruder,and the resulting blends spun to produce a series of reinforced polymer fibres.The aim wasto compre the dispersion and resultig mechanical propeties achieved for nanotubes produced by the electric arc and a variety of chemcial vapour deposition techniques.a high quality of dispersion was achieved for all the catalytically-grown materials and the greatest improvements in stiffness were observed using alinged,substrate-grown,carbon nanotubes.The use of entangled multi-wall carbon nanotubes led to the most pronounced increase in yield stress,most likely as result of increased constraint of the polymer matrix due to their relatively high surface area.The degrees of polymer and nanofiller alignment and the morphology of the polymer matrix wer assessed using X-ray diffraction and differential scanningcalorimetry.The carbon nanotubes were found to act as nucleation sites udne rslow cooling conditions,the effect scaling with effective surfacearea.nevertheless,no significant variations in polymer morphology as a function of nanoscale filler type and loading fraction were observed under the melt spinning ocnditions appleid.A simple rule-of-mixture evaluation of the nanocomposite stiffness revealed a higher effectiv emodulus for the multi-wall carbon nanotubes compared to the carbon nanofibres,as a result of improved graphitic crystallinity.In addition,this appraoch allowed a general comparison of the effectie nanotube modulus with those of nanoclays as well as common short glass and carbon fibre fillers in melt-blended polyamide composites.The expeimental results further highlight the fact that the intrinsic crystalline quality,as well as the straightness of the embedded nanotubes,are significnat factors influencing the reinforcement capability.