Polyethylene/silica nanorod composites with reduced dielectric constant and enhanced mechanical strength

Reinforcement of materials with low dielectric constant by nanofillers has attained more and more attention. Conventional 1D nanofillers, such as carbon nanotubes, significantly enhance mechanical properties of polymers; however, they do not reduce dielectric constant. In this study, silica nanorods (SNR) were used to prepare polyethylene composites by mechanical blending followed by hot pressing. It was found that the incorporation of SNRs enables enhancement of strength and elastic modulus. Dielectric constant did not increase as predicted when SNRs were incorporated into polyethylene (PE); on contrary, it considerably decreased from similar to 2.4 to around similar to 2.2 at SNR loading of 5 wt %. However, when glass fibers were used as fillers, we did not observe such decrease. SEM image and density measurement indicated that the composites were compact with very low porosity. We believe that the incorporation of SNRs alters crystalline and chain arrangement of PE, thus reduces the polarization and dielectric constant. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47143.