PREDICTION OF MECHANICAL PROPERTIES OF CARBON NANOTUBE/POLYVINYLIDENE FLUORIDE COMPOSITES BY HANSEN SOLUBILITY PARAMETERS METHOD

In this work, Hansen solubility parameters [1] (HSP) are introduced to predict the physical properties of filler-matrix composite system. This highly efficient and economical method could be potentially applied in both control and guiding of composites processing. Excellent mechanical properties of carbon nanotubes (CNTs) enable them an excellent choice of reinforcement material for polymeric composites [2, 3]. However, due to the high aspect ratio, CNTs tend to form agglomerates, which cause the dispersion of carbon nanotubes in polymer matrix a big challenge. In order to obtain good nanotube dispersion, many methods have been tried, among which modification of the CNTs and ultrasonic dispersion are widely used [4-6]. Normally the dispersion state of the nanotubes in the polymer is evaluated after the whole composite fabrication process is completed. However, using Hansen solubility parameters (HSP) could help predicting the dispersion state of the CNTs in polymer before fabricating the composites. In this study, the mechanical properties of carbon nanotube / Polyvinylidene Flouride (PVDF) are investigated. Equal amount of purified single walled carbon nanotubes (SWNTs), nitric acid treated SWNTs, octadecylamine (ODA) modified SWNTs and multi-walled carbon nanotubes (MWNTs) blends with piezoelectric polymer PVDF have been prepared by using dimethylformamide (DMF) solution blending and injection molding method. The HSP of the various carbon nanotubes have been determined in order to predict the physical affinities between the PVDF and the various CNTs. The dispersion state of nanotubes in PVDF matrix was observed by light optical microscopy (LOM) and compared with the HSP. The prediction of the physical compatibility of CNT / PVDF composite materials by the HSP method will be discussed in this paper. The mechanical properties of neat PVDF and PVDF composites were measured by tensile tests. The Young’s modules, ultimate tensile strength, and toughness of the PVDF composites are enhanced or affected in different extents by adding carbon nanotubes.