Análisis térmico y microestructural de matrices compuestas de polihidroxialcanoatos y ácido poliláctico

JUAN CARLOS ALZATE MARIN, SANDRA RIVERO , ADRIANA PINOTTI, ALEJANDRO CARAVELLI , NOEMÍ ZARITZKY.

CORDOBA

Congreso; 16º Congreso Internacional de Metalurgia y Materiales SAM-CONAMET 2016; 2016

Univ Tecnologica Nacional

The objectives of the work were to develop individual and composite matrices based on polylactic acid (PLA) and polyhydroxyalkanoates (PHA), studying their thermal and microstructural properties. PHAs were obtained in the lab through a biotechnological process from a wastewater (cheese whey) from an activated sludge. Solutions were prepared by dissolving PHA and PLA in chloroform 1 and 2% (w/v), respectively and subsequent casting. The blends were prepared with the following proportions PLA/PHA: 20/80, 40/60, 60/40 and 80/20 (w/w). Individual as well as composite films showed structural integrity; SEM and FTIR studies highlighted the immiscibility of the blends. The micrographs revealed that the crystalline phase of PHA was interspersed with the PLA amorphous fraction. Thermal analysis by modulated DSC of individual films ex-hibited peaks at 147.7°C and 172.7°C, corresponding to PLA and PHA, respectively. Throughout the heating, blends 40/60 and 60/40 presented two peaks attributed to crystalline domain melting of each polymer. Du-ring the cooling stage, only 20/80 and 40/60 matrices showed a crystallization peak due to PHA. These re-sults were consistent with the FTIR spectra, which showed the band at 1718 cm-1 attributed to the crystalline fraction of PHA. Even though thermal and microstructural analyses revealed the immiscibility of these polymers, its blend allowed obtaining a material where the PHA crystallizes as small spherulites acting as nucleating agents capable of recrystallizing the PLA and modifying film properties. Higher crystallization degree of the blends 20/80 and 40/60 was confirmed by means of X-rays, showing the diffractograms of individual matrices, peaks of higher intensity. These results constitute a progress in the material area, ena-bling the use of these blends for specific applications.