IMPROVED PROPERTIES OF CARBON NANOTUBE/POLYMER NANOCOMPOSITES USING A SUPERCRITICAL CO_2 AIDED MELT BLENDING METHOD

摘要

Improvements in carbon nanotube (CNT) dispersion and subsequent mechanical properties ofrnCNT/poly(phenylsulfone) (PPSF) composites were obtained by applying the supercritical CO_2rn(scCO_2) aided melt blending technique that has been used in our laboratory for nanoclay/polymerrncomposite preparation. The preparation process relied on rapid expansion of the CNTs followedrnby melt blending using a single-screw extruder. Scanning electronic microscopy (SEM) resultsrnrevealed that the CNTs exposed to scCO_2 have a more dispersed structure. Further optimizationrnof the nanotube expansion process will be investigated in order to completely disentangle thernnanotube bundles before the melt compounding step. Microscopy results showed improved CNTrndispersion in the polymer matrix and more uniform networks formed with the use of scCO_2,rnwhich indicated that CO_2 expanded CNTs are easier to disperse into the polymer matrix duringrnthe blending procedure. The CNT/PPSF composites prepared with scCO_2 aided melt blendingrnand conventional melt blending showed similar tensile strength and elongation at break. ThernYoung’s modulus of the composite prepared by means of conventional direct melt blendingrnfailed to increase beyond the addition of 1 wt% CNT, but the scCO_2 aided melt blending methodrnprovided continuous improvements in Young’s modulus up to the addition of 7 wt% CNT. Duernto their high cost, it is desirable to see these improvements at lower nanotube concentrations.rnEfforts at controlling orientation of the nanotubes, and future work on nanocomposites of polarrnpolymers with polar functionalized nanotubes will seek to rectify this.