Temperature dependence of interfacial thickness and conductivity of SIO2/LDPE composite films. (April 2017)

• Record Type: Journal Article
• Authors: Yao, Lei; Yin, Jinghua; Zhao, Hong; Yang, Jiaming; Chen, Minghua; Han, Baozhong; Su, Bo; Mo, Guang
• Is Part Of: European polymer journal. Volume 89(2017)
• Page Start: 119
• Page End: 128
• Publication Date: 2017-04
• Subjects: Synchrotron radiation SAXS -- Interface layer -- Composite film -- SiO2 nanoparticle -- Conductivity; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; Polymerization; Polymers; Periodicals; Electronic journals; 547.705
• DOI: 10.1016/j.eurpolymj.2017.02.002
• Languages: English
• ISSNs: 0014-3057

Abstract

Graphical abstract: The interfacial layer thickness varies with temperature, that during 30 °C → 100 °C, the thickness increases from 2.8 nm to 3.5 nm, and remains constant beyond 100 °C. Due to the greater binding effect between the interfacial layer of the composite film, its conductivity is two orders of magnitude smaller than that of pure polyethylene film, resulting to significant improvement of insulating property. Highlights: Interfacial layer thickness increases during 30→100 °C and is a constant beyond 100 °C. The increase of interfacial thickness is caused by the melting of lamellae of LDPE. The interface layer limits the space charge accumulation of the film, effectively. Abstract: A melt-blending process was adopted to prepare a 5 wt% and 150 μm thick SiO2 /LDPE (Low-Density Poly-Ethylene) composite film, to study the influence of the microstructure evolution of the composite film on its conductivity when the temperature changes. The results show that there is an interface layer between SiO2 and PI polymer matrix in composite film. When temperature varies from 30 °C to 100 °C, the interfacial thickness increases from 2.8 nm to 3.5 nm, and remains constant beyond 100 °C. DSC (Dynamic Stability Control) shows that this increase is mainly caused by the melting of lamellae of polyethylene polymer chains. DMA (Dynamic Mechanical Analyzer) indicates the bound effect of the interface on the polymer chains of the composite film. When temperature changes from 30 °C to 70 °C at the heating rate of 10 °C/min, the conductivity values of LDPE and SiO2 /LDPE change from 1 × 10 −16 to 1 × 10 −14 s/m, 1.5 × 10 −16 to 1.7 × 10 −16 s/m, respectively. The conductivity of the composite film becomes 2 orders of magnitude smaller than that of pure polyethylene film. The increases of interface layer limit the space charge accumulation effectively, and lowers the sensitiveness of conductivity to temperature, resulting in significant improvement of insulating property.