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The optimum dispersion time of nanoparticles is important for obtaining uniform dispersion of fillers or other additives in a matrix. In this study, the optimal dispersion time of carbon nanotube (CNT) in a matrix was investigated using cyclic voltammetry (CV), measurement for different dispersion methods and times. In addition, the mechanical properties of CNT composites manufactured using different dispersion methods were evaluated by tensile and flexural tests. The CV and mechanical test results were correlated to the dispersion condition of CNT in the composites. It was found that tip-type sonication resulted in better dispersion than bath-type sonication. Improved CNT dispersion resulted in composites with both enhanced CV measurements and improved mechanical properties. In the study reported here, improvements in dispersion were generally accompanied by higher electrical currents. This suggests that the CV measurement method is an effective tool for determining optimal dispersion times, for different CNT dispersion processes. [ABSTRACT FROM PUBLISHER]

Electrospun polyvinylidene fluoride (PVDF)-containing carbon nanotubes (CNT) were prepared for use in fabricating actuator materials. Actuating displacement was measured in an electrochemical environment. The electrospun nanofibers were arranged using a drum-type collector, and morphology was investigated using a field emission-scanning electron microscope. The uniformity of dispersion of CNT in the PVDF nanofibers was monitored by electron probe X-ray micro-analysis. Tensile strength and electrical resistivity results were used as an indication of the state of alignment. The electrospun CNT/PVDF nanofiber sheets exhibited better mechanical and electrical properties in the arranged direction. The efficiency and electrical capacities of electrospun CNT/PVDF nanofiber sheet were compared with those of cast PVDF sheets for use in actuator applications in electrochemical environments. The electrospun CNT/PVDF nanofiber sheets exhibited much better actuator performance than PVDF sheets, which are attributed to their superior electrical properties. Highlights (1) The interfacial durability of CNT/PVDF nanofibers was enhanced to increase contact area by reinforcing CNT. (2) The efficiency of CNT/PVDF actuators was improved due to interfacial properties. (3) Thin thickness drum-type collector was made to enhance nanofiber alignment. (4) The arranged CNT/PVDF nanofibers exhibited better mechanical and actuating displacements. [ABSTRACT FROM AUTHOR]

Nondestructive evaluation methods have been utilized to detect and to prevent structural damage in research and development. Most such detection methods used expensive external sensors to detect damage. This paper explores the use of a less expensive electrical resistance measurement method for damage and strain sensing resulting from electrical signal variations, induced by stresses or shape changes in conductive materials. This method of damage sensing was performed first on carbon fibers composites, and in this study, its use is extended to conductive nanoparticles composites. Self-sensing can also be used to evaluate the interfacial properties of fiber-reinforced polymer composites. This electrical resistance measurement method had several advantages compared to other nondestructive evaluation methods such as better stability, lower cost, and being rather simple. Future plans are to include studies of this nondestructive method into the manufacturing and robotic fields. [ABSTRACT FROM PUBLISHER]