The effects of concentration of LiClO4 and melt compounding conditions on structure-properties of ion conductive films prepared from scrap PVB

This research work has concerned the development of ion conductive poly(vinyl butyral) (PVB) films for use as solid polymer electrolyte layer in smart window applications. In this study, attempts were made to prepare the ion conductive PVB films via a melt process, using a scrap PVB film from laminated glass factory as the raw material. The aim of this work was to investigate effects of mixing time (ranged between 3-12 minutes), temperature (125–145ºC), and concentration of LiClO₄ (20–40 wt%) on optical, thermal properties, and ionic conductivity of the products. From the results, it was found that distribution of LiClO₄ powder in PVB phase and homogeneity of the extrudates increased with mixing time and temperature. However, discoloration of the extruded PVB, loaded with 20 wt% LiClO₄, was observed when the time and temperature were increased above 12 min and 135°C, respectively. The extrudates also turn dark faster when the concentration of LiClO₄ was increased. This was ascribed to thermal degradation of the polymer. As the concentration of LiClO₄ was increased, percentage visible light transmittance and ionic conductivity of the PVB films dropped. In this study, the optimum conditions for producing ion conductive PVB film refer to those prepared by mixing of 20 wt% of LiClO₄ with scrap PVB in a micro-compounder at 135ºC for 12 minutes. This product yielded highest ion conductivity of 2.14×10^-7 S/cm without any discoloration.