Foaming of aliphatic polyester using chemical blowing agent

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 PEAS 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 = 100:8 phr) was examined to prepare expanded PEAS foam. Low-density PEAS 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 PEAS foams was investigated. A closed-cell structure PEAS foam of high blowing ratio (density about 0.05 g/cm(3)) could be obtained by adding 3 phr DCP. To manufacture expanded PEAS 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. (C) 2001 John Wiley & Sons, Inc.