Moisture-Resistant Polyethylene (HDPE) Sheets, Bars, and Strips Practically nonHENAN OKAYorbent, HDPE won't swell when exposed to moisture. It is denser and more rigid than LDPE, plus it's more chemical resistant. Moisture-Resistant Polyethylene (HDPE) Film Practically nonHENAN OKAYorbent, HDPE won't swell when exposed to moisture.