A Study of Diffusion of O2 in Polyethylene/Poly (Urea Formaldehyde) Composites Using Molecular Dynamics Simulations

The self-healing microcapsule of dicyclopentadiene (DCPD) as the core material and poly (urea formaldehyde) (PUF) as the wall material can be doped into dielectric materials for the self-healing. However, the doping of excessive PUF microcapsules into polyethylene (PE) materials can accelerate the aging of composites. The diffusion of O
₂
into PE/PUF composites was studied to improve the anti-aging property of materials. Three PE/PUF doped models with varying PUF concentrations and one PE/PUF/SiO
₂
doped model were designed. MSD and diffusion coefficient of O
₂
were calculated and analyzed by molecular dynamics simulation. The results showed that the diffusion of O
₂
accelerated when the PUF concentration exceeded 10%. But it can inhibit the diffusion of O
₂
by adding nano-SiO
₂
into PE/PUF composites. It was found that there were hydrogen bonds and Van der Waals forces between polymers (PE and PUF) and nano-SiO
₂
by analyzing the internal mechanism. Hydrogen bonds and Van der Waals forces made polymers chains absorb on the surface of nano-SiO
₂
and reduced the distances between polymers chains, thereby inhibit diffusion of O
₂
and improved the anti-aging property of composites.