Isosorbide plasticized corn starch filled with poly(3-hydroxybutyrate-co-3-hydroxyvalerate) microparticles: Properties and behavior under environmental factors.

In this work, new green and fully biodegradable composites, based on corn starch, plasticized with two different amounts of isosorbide and filled by poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) microparticles, were obtained by melt processing. The analysis of their morphologies, crystallinity, structural interactions and dynamomechanical properties as well as the evaluation of their moisture resistance and biodegradability in soil, were performed in function of the plasticizer and/or microparticle amount. The analysis of morphology, crystallinity and structural interactions showed that the plasticization process was completed under the melting processing conditions used. The microparticles were homogeneously dispersed in the thermoplastic starch matrix without suffering any deformation or breaking during the processing. Biocomposites with adequate storage modulus values were obtained, especially the TPS plasticized with 35% of isosorbide and filled with 5 wt% of PHBV microparticles. The incorporation of PHBV microparticles leads to biocomposites with higher moisture resistance. All the biocomposites were completely biodegraded in soil in a short period of time. The performed study demonstrated that these biocomposites could be used for applications in the packaging industry.

Properties and behavior under environmental factors of isosorbide-plasticized starch reinforced with microcrystalline cellulose biocomposites.

Green biocomposites based on corn starch plasticized with isosorbide and glycerol and filled with microcrystalline cellulose (MCC) were processed. The structural interactions, dynamomechanical properties, water absorption, and soil biodegradability were investigated by different techniques considering the effect of the type and amount of plasticizer and the MCC addition. The changes along the time of the structural interactions and the dynamomechanical properties of these materials and the influence of the retrogradation phenomenon were also studied. The use of isosorbide as plasticizer instead of glycerol improved the stiffness, the water absorption and the biodegradation rate of thermoplastic starch (TPS). Moreover, no evidence of retrogradation for isosorbide was observed. An isosorbide content of 35% and the addition of MCC filler enhanced in a greater extent these properties with a complete biodegradability in 7 month. These green biocomposites can be an alternative for food packaging applications.

Corn starch plasticized with isosorbide and filled with microcrystalline cellulose: Processing and characterization.

Innovative, green and fully biodegradable biocomposites, based on plasticized corn starch, were prepared by melt processing and filled with microcrystalline cellulose (MCC). Isosorbide and glycerol were used as plasticizers. The effect of the type and content of the plasticizer and the filler addition on processing, surface morphologies, crystallinity and thermal stability were investigated. Aged materials were analyzed too to study the retrogradation phenomena along the time. The processing using isosorbide required lower temperatures but greater shear and processing times leading to more homogeneous biocomposites. With isosorbide, higher crystallinity and no retrogradation signals were observed as clearly occurred with glycerol. The thermal stability of biocomposites was high too. These properties enhanced in a greater extent when the isosorbide content was 35% and with the MCC incorporation, the last due to a good adhesion of MCC to the matrix. These biocomposites could be a good option for packaging applications.