2. Materials and methods2.1. MaterialsPVC plastics (Table 1) with different content of calcium car-bonate (CaCO3) or di-n-octyl phthalate (DnOP) serving as additiveand waste PVC plastics were chosen to investigate the effects ofadditives on the surface of PVC plastics. The samples of waste PVCplastics were achieved from decorative buckle and rain boot, andthey were referred as PVC-dec and PVC-sho in this paper, respec-tively. The plastic samples for flotation tests were shredded andscreened, and the sieve size used in this study was −1 mm and+1–2 mm.Distilled water, glycerol, formamide, ethylene glycol anddiiodomethane were used as probe liquids to measure the contactangles between the liquids and surface of PVC plastics; glycerol,formamide, ethylene glycol and diiodomethane were chemicallypure and used as received. Tap water was used throughout theflotation tests.