Preparation and Characterization of Exfoliated PHBV Nanocomposites to Enhance Water Vapor Barriers of Calendared Paper

The water vapor transmission rates (WVTRs) of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (PHBV) and PHBV/nanocomposite-coated papers were measured at various levels of relative humidity and temperature. The coating of PHBV on base paper was performed with two different methods, and the more effective one for lowering WVTR values was utilized for coating the PHBV/nanocomposites on the paper. Nanocomposites of PHBV were prepared with a commercial montmorillonite Cloisite30B (CS30B), and a novel modified clay was obtained via a solution-blending process. To prepare the series of modified clays, which were coined here as HPGC, MPGC, and LPGC, we intercalated β-butyrolactone in the Cloisite30B clay by a ring-opening polymerization. The morphology of the clay and nanocomposites was revealed by X-ray diffraction. Additionally, the dispersion and phase behavior of the clay in the PHBV matrix was observed using a transmission electron microscope. It was found that the coating method and clay exfoliation were the...