The complex polycrystalline systems consisted of stereocomplex (Sc) and α crystals were prepared by meltmixing PLLA with PDLA. The mechanism of inducing and forming the complex crystalline structure was studied under compound phenylphosphonic acid zinc salt (CNA) and two supercritical fluids. The results shown that increase PDLA content was a useful way to control the Sc/α polycrystalline structure. With the PDLA content increase

the crystallinity of Sc increase from 0.4% to 7.00%

but the crystallinity of α decrease from 17.19% to 1.29%. Meanwhile

CNA is an efficient crystal promoter and nucleator agent. With the adding of CNA

the crystallinity of both Sc and α increased. The supercritical N

2

and CO

2

are plasticizers. And the plasticization effect of CO

2

is more obvious than that of N2. Under the two supercritical fluids

the Sc crystallization was suppressed

whereas the α crystallization was promoted. The co-existing of CAN and the two supercritical fluids could suppress the Sc crystallization. And

the α crystallinity was greatly increased. Eventually

the crystallinity of Sc and α could reach the maximum of 8.07% and 24.55%

respectively.