Nano-SiO2 Grafted with Aromatic Compound Improving Breakdown Strength of Low-Density Polyethylene -Part I: Sample Preparation

This work focuses on improving breakdown strength of low-density polyethylene (LDPE) by doping nano-SiO₂ grafted with aromatic compounds terminated by alkyl chains. In the first part of the work, quantum chemical calculation is employed to estimate and select the aromatic compound. The selected aromatic compound is grafted onto the nano-SiO₂ surface via an amidation reaction. Alkyl chain is grafted as the terminal group of the aromatic compound to enhance the compatibility between the additive and the LDPE matrix. Fourier transform infrared spectroscopy, thermogravimetric analysis, and zeta potential measurements are systematically utilized to verify the surface treatment effectiveness of nano-SiO₂. The compatibility between the modified nanoparticle and the LDPE is estimated through molecular dynamics simulation. The results confirm the successful surface grafting of nano-SiO₂ with 4,4´-stilbenedicarboxylic acid (SDA) terminated by alkyl chains. The alkyl chain improves the compatibility of the SDA-grafted nano-SiO₂ with the LDPE matrix by strengthening the intermolecular interactions. This approach is expected to enhance the breakdown strength of LDPE.