Poly(butylene adipate-co-succinate) (PBAS), a saturated aliphatic polyester cured by dicumyl peroxide (DCP), was prepared and the viscoelastic property was investigated. The viscosity of crosslinked PBAS increased, and it exhibited rubbery behavior as the content of curing agent was increased. The results suggested that the viscosity and elasticity of PBAS could be regulated by adding a small amount of DCP; hence, the processibility could be improved. Prior to foaming, a proper formulation of blowing agent (blowing agent/urea activator ϭ 100:8 phr) was examined to prepare expanded PBAS foam. Low-density PBAS expanded foams were prepared using a chemical blowing agent and DCP. The effect of the foaming temperature, additive content, and curing agent content on the blowing ratio and morphology of expanded PBAS foams was investigated. A closed-cell structure PBAS foam of high blowing ratio (density about 0.05 g/cm 3 ) could be obtained by adding 3 phr DCP. To manufacture expanded PBAS foam under 0.1 g/cm 3 using a chemical blowing agent, the storage modulus of the matrix polymer should exceed the loss modulus by enough to stabilize growing bubbles.

We attempted to introduce crosslinking into poly(butylene adipate-co-succinate) (PBAS) to improve the properties, such as the mechanical strength and elasticity, by a simple addition of dicumyl peroxide (DCP). Prior to curing, the thermal stability of PBAS was investigated. Above 170°C PBAS was severely degraded, and the degradation could not be successfully stabilized by an antioxidant. The PBAS was effectively crosslinked by DCP, and the gel fraction increased as the DCP content increased. A major structure of the crosslinked PBAS was an ester and aliphatic group. The tensile strength and elongation of PBAS were improved with an increasing content of DCP, but there was little affect on the tear strength. The biodegradability of crosslinked PBAS was not seriously deteriorated. A higher degree of crosslinking gave a lower heat of crystallization and heat of fusion. However, the melt crystallization temperatures of the crosslinked PBAS were higher than that of PBAS.

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Poly(phenylene sulfide ketone) (PPSK) was synthesized by the reaction of sodium sulfide with 4,4Ј-dichlorobenzophenone in N-methyl-2-pyrrolidinone through the Phillips process. The effect of water hydration of sodium sulfide in solution, polymerization temperature, polymerization time, and stoichiometric ratio of monomers on the polymerization behavior of PPSK were investigated with respect to inherent viscosity and yield. Thermal degradation parameters of PPSK synthesized were investigated by dynamic thermogravimetry. To determine thermal degradation energy, Kissinger, Ozawa, and Friedman methods were used and activation energies were 202.3, 233.6, and 232.2 kJ/mol, respectively.