In order to obtain crosslinked poly(butylene succinate) (PBS) foams with a closed-cell structure, a commercial-grade PBS was first modified in the melt using two different branching agents to increase the melt viscosity. The rheological properties of the branched and crosslinked PBS were examined by varying the amount of the branching agents. The complex viscosity of the crosslinked PBS increased with increasing amount of the branching agent. However, it decreased with increasing frequency. When 2 phr of the branching agent was added to PBS, the storage modulus (G') was higher than the loss modulus (G") throughout the entire frequency range, showing that the addition of a branching agent increases the melt viscosity and elasticity of PBS effectively. Closed-cell PBS foams were prepared by mixing the chemical blowing agent with the crosslinked PBS. The effect of the foaming conditions such as temperature and time, and the amount of the crosssslinking agent on the structure of the expanded PBS foams were also investigated.

Synthetic aliphatic biodegradable poly(butylene succinate) (PBS) nanocomposites with multiwalled carbon nanotube (MWNT) were investigated to study the effects of the preparation method and MWNTs on physical characteristics of biodegradable polymer nanocomposite foams. PBS nanocomposites were prepared by the solution blending and melt mixing methods. Nanocomposites of PBS/MWNT were also prepared by the SOAM method, where the solution-blended nanocomposites were further mixed in the melt state. The dispersion of MWNTs in the PBS matrix was characterized by FT-Raman spectroscopy, field-emission scanning electron microscopy (FE-SEM), and field-emission transmission electron microscopy (FE-TEM). The mechanical and thermal properties of the PBS nanocomposites were measured using a universal test machine (UTM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Nanocomposite foams with high-density closed cells were prepared by using a chemical blowing agent (CBA) that acted as a cell-nucleating agent. The effects of the foaming conditions and MWNTs on the blowing ratio, cell size distribution, and morphology of the expanded PBS foams were investigated. The effect of the CBA content on the blowing ratio, cell size distribution, and morphology was also investigated.

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