The overlooked key factors for accurate determination of polymer triboelectric series

• • Protein composite films containing 30 wt% glycerol exhibit triboelectric polarities that diverge discernibly from those of pure protein films, invalidating polarity rankings that neglect plasticizer content; industrial TENG design must specify additive-free or controlled-additive formulations to ensure reproducible charge transfer. • • Hygroscopic polymers tested without rigorous drying yield measurement artifacts where recorded polarity reflects a water-containing composite rather than the pure polymer; high-humidity conditions exacerbate this, mandating standardized drying protocols (e.g., vacuum or inert atmosphere) prior to contact-separation testing. • • Surface roughness disparities between porous cellulose and chitosan aerogel films produce unequal effective contact areas with PTFE, introducing errors in quantifying amine versus hydroxyl contributions to positive triboelectric polarity; identical surface roughness across samples is required for valid series determination. • • Inconsistencies in film synthesis—solution-drying for PLGA and PLA versus paper-based films—coupled with variations in mass and thickness, modulate charge transfer magnitude; standardization of shape, contact area, and thickness is essential to isolate intrinsic triboelectric behavior from geometric artifacts.