Toward the preparation of nanocomposites with oriented fillers: Electric field-manipulation of cellulose whiskers in silicone oil

In this paper, the behavior of cellulose whiskers (CWs) in silicone oil is examined under the influence of an AC electric field. The whiskers first rotate in the direction of the electric field, then the ends of the whiskers interact with each other to form chains. Alignment and chain formation were found to be functions of electric field magnitude, frequency, and duration. The driving force for chain formation is thought to be dielectrophoresis. The optimal alignment with chain formation was achieved at 3000 V_pp mm ^-1 and 500 mHz for a duration of 20 min. The dielectric constant of the solutions was studied as a function of microstructure. In general, the dielectric constant for the aligned samples increased as compared to the random case. The highest increase was achieved at the optimum conditions mentioned above. It is also found that the thickness and length of formed CW chains impact the effective properties, resulting in an almost three-fold increase in dielectric constant. Future work will focus on the alignment of individually dispersed CWs in a polymer matrix to prepare nanocomposites with oriented CWs. Based on our results here, aligning CWs in polymers is expected to significantly enhance electrical and mechanical properties.