3/16/2011
Effect of Growing Crystalline Phase on Bubble Nucleation in Poly(L-Lactide)/CO2 Batch Foaming
(3247–3252) Industrial & Engineering Chemistry Research 50 #2 (2011)
Taki, Kitano and Ohshima of Kyoto University, Japan, found that spherulites (crystalline phase) grown in a semicrystalline poly(L-lactide) (PLLA) matrix enhanced carbon dioxide (CO2) bubble nucleation in a batch foaming process.  The number of nucleating bubbles increased as a function of increasing spherulite quantity and area. A faster linear spherulite growth rate and a lower hold-temperature created more bubbles around the spherulites. From these observations, it was concluded that the growing spherulites expelled CO2 from the advancing spherulite−amorphous phase interface and that CO2 accumulated at the interface. Then, the increase in the concentration of CO2 led to an increase in the nucleation of bubbles around the spherulites.  (RDC 3/16/2011)