Cross-linked and uncross-linked biodegradable nanocomposites. I. Nonisothermal crystallization kinetics and gas permeability

Various nanocomposites of poly(butylene succinates) (PBS) with different ratios of organically modified layered silicates (OMLS) were prepared. Moreover, such PBS nanocomposites cross-linked by dicumyl peroxide (DCP) were also prepared in this work. Effects of cross-linking and OMLS on nonisothermal crystallization kinetics and the gas permeability of PBS samples were investigated further. WAXD indicates that the layers of clay were intercalated by the modifiers, and that the interlayer distance of OMLS in the nanocomposites could be expanded to about 2.96 nm. The results of DSC analysis revealed that the crystallization temperature of nanocomposites shifted to the lower temperature with the increase of OMLS content. With the addition of OMLS, crystallinity was decreased, whereas the half-life of crystallization was increased. On the other hand, even the cross-linked effects also increased the half-life of crystallization of the materials, but did not necessarily decrease crystallinity in all cases. Moreover, the PBS/OMLS nanocomposites showed a 23.87-46.64% decrease in permeability of oxygen when compared with the pristine PBS sample. Yet, the crosslinked nanocomposites exhibited decrements of 6.3839.53%. This indicates that the gas permeability of PBS was more effectively depressed by the addition of OMLS than by the cross-linking reaction. The cross-linked structure of polymer seemed not to be very effective in decreasing the gas permeability of FIBS. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110: 1069-1079, 200