Low‐temperature clean preparation of poly(lactic acid) foams by combining ethyl lactate and supercritical CO 2 : correlation between processing and foam pore structure

• Published in: Polymer international Vol. 63; no. 7; pp. 1303 - 1310
• Main Authors: Salerno, Aurelio, Domingo, Concepción
• Format: Journal Article
• Language: English
• Published: 01.07.2014
• ISSN: 0959-8103; 1097-0126
• DOI: 10.1002/pi.4677

This study reports the low‐temperature and clean fabrication of porous poly(lactic acid) ( PLA ) through solid‐state foaming using various mixtures of ethyl lactate ( EL ) and supercritical CO 2 ( scCO 2 ) as the blowing agent. Results showed that adding a small amount of EL (up to 0.2% molar fraction) to scCO 2 enhanced the plasticizing effect of the blowing agent mixture. As a direct consequence, at an operating temperature of 35 °C, PLA foams could be manufactured with homogeneous morphology, density as low as 0.09 ± 0.01 g cm −3 , mean pore sizes up to 519.0 ± 205.0 µm and pore densities in the range 2.0 × 10 5 to 3.4 × 10 8 pores cm −3 . Conversely, at a temperature of 40 °C, an increase of plasticizer concentration in the blowing agent mixture up to 0.2% promoted the crystallization of the polymer during sorption stage and, consequently, foaming was slightly reduced. © 2013 Society of Chemical Industry