Low‐temperature clean preparation of poly(lactic acid) foams by combining ethyl lactate and supercritical CO2: correlation between processing and foam pore structure |
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Authors: | Aurelio Salerno Concepción Domingo |
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Affiliation: | Institute of Materials Science of Barcelona (ICMAB‐CSIC), , Bellaterra, 08193 Spain |
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Abstract: | 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 CO2 (scCO2) as the blowing agent. Results showed that adding a small amount of EL (up to 0.2% molar fraction) to scCO2 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 × 105 to 3.4 × 108 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 |
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Keywords: | ethyl lactate poly(lactic acid) pore structure low‐temperature foaming supercritical CO2 |
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