Effects of LiTFSI loading on thermal, mechanical and ion conducting properties of specialty interlayer films derived from scrap PVB

This work investigates the feasibility of using scrap poly(vinyl butyral) (PVB) film derived from laminated glass factories as an ion-conductive interlayer film for producing electrochromic glass. The process uses PVB films made from masterbatches containing 10 to 60 wt% lithium bis(trifluoromethane sulfonyl)imide (LiTFSI). The investigation focused on how LiTFSI loading affected both the PVB masterbatches and the final PVB films. Higher LiTFSI loading correlated with increased ionic conductivity. The best electrochromic devices are obtained when the PVB films are directly prepared from the masterbatch without additional PVB flakes dilution during extrusion. The highest ionic conductivity 2.72×10^-4 S/cm, is achieved from a masterbatch containing neat PVB and scrap PVB flakes with 60 wt% LiTFSI. Additionally, LiTFSI acted as a plasticizer for PVB, lowering the glass transition temperature and increasing the PVB film percent elongation.