In-situ synchrotron radiation SAXS study of structural deformation memory effect of the interfacial region in Al2O3/LDPE composite film

Abstract

This paper employs the SAXS technique to study the microstructure evolution of nano Al2O3/low-density polyethylene (LDPE) composite film during temperature increase and decrease (including interfacial layer thickness, mass fractal and surface fractal), and discusses the deformation memory effect (DME) mechanism. Compared with the case of pure LDPE, there are some new phenomena observed in the Al2O3/LDPE composite film, such as an interfacial layer and surface fractal. The experimental results showed that, when the temperature rose from 25 °C to 180 °C, the interfacial layer thickness of the composite film increased from 2.8 nm to 3.5 nm, and the surface fractal dimension increased from 1.2 to 2.0, with the lamellar crystal of the PE molecular chains melting. When the temperature dropped from 180 °C to 30 °C, the interfacial layer thickness decreased from 3.5 nm to 3.0 nm, and the surface fractal dimension changed from 2.0 to 1.2, with the PE molecular chains recrystallizing. We found that the DME of the interface layer is that thickness and area increase when temperature rises and decrease when temperature decreases. The addition of Al2O3 nanoparticles into the polymer results in the adsorption of space charges in the matrix onto the nanoparticles and in the interfacial regions, which efficiently inhibits the space charge accumulation of the composite material in the gradient electrical field.