Carbon dioxide‐induced crystallization in poly(L‐lactic acid) and its effect on foam morphologies

The effect of carbon dioxide (CO 2 ) on the physical properties of poly( L ‐lactic acid) (PLLA) and on the formation of crystalline domains was investigated. The presence of CO 2 in the matrix was found to induce crystallization in PLLA, with the crystallinity increasing with increasing CO 2 pressure. The combination of saturation conditions and formation of crystalline domains was studied for its effect on the formation of porous morphologies in PLLA. Moreover, the effect of CO 2 on PLLA properties and formation of porous structures was further exploited by first creating crystalline domains in samples using CO 2 at various pressures at 25 °C and then re‐saturating the same samples with CO 2 at a constant pressure of 2.8 MPa and 0 °C. This paper reports on the solubility of CO 2 at 25 and 0 °C in PLLA, crystallization and subsequent effect on foam morphologies when processed using different saturation cycles. Unique and intriguing morphologies were obtained by specifically controlling the properties of PLLA.