Effects of surface modification on interfacial and rheological properties of CCTO/PEN composite films

To investigate the structure of surface modified Calcium copper titanate (CCTO) granules, transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) of surface modified CCTO granules were studied. Using this method, convincing evidence was provided for the successful coating. The measurement of scanning electron microscope (SEM) revealed that a relatively strong interaction exists between CCTO granules and PEN compare with the unmodified CCTO/PEN, leading to a good dispersion of CCTO in the polymer matrix. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) indicated that the initial decomposition temperatures and the maximum decomposition rate temperatures were all above 475 °C and the glass transition temperatures of the composite films were in the range of 224–229 °C, indicating that the composite films possess high thermal stability, which can be better meet the satisfy of practical application. To obtain more information of interfacial interaction of the filler and matrix, the rheological behaviors of surface modified calcium copper titanate (CCTO)/polyarylene ether nitriles (PEN) dispersions during the curing process were investigated with parallel-plate rheometry to evaluate their crosslink structure. From the figures of storage modulus, loss modulus and complex viscosity, it is confirmed that an abrupt transition occurred during the curing process of the dispersions, that is, the state of this percolated network underwent elastic solid to viscous liquid transition. In addition, to gain a better understanding of the composite films, the properties of mechanical and dielectric were also characterized.