Rebeca Bouza

Horse chestnut (Aesculus hippocastanum L.) starch: Basic physico-chemical characteristics and use as thermoplastic material.

Starch isolated from non-edible Aesculus hippocastanum seeds was characterized and used for preparing starch-based materials. The apparent amylose content of the isolated starch was 33.1%. The size of starch granules ranged from 0.7 to 35 μm, and correlated with the shape of granules (spherical, oval and irregular). The chain length distribution profile of amylopectin showed two peaks, at polymerization degree (DP) of 12 and 41-43. Around 53% of branch unit chains had DP in the range of 11-20. A. hippocastanum starch displayed a typical C-type pattern and the maximum decomposition temperature was 317 °C. Thermoplastic starch (TPS) prepared from A. hippocastanum with glycerol and processed by melt blending exhibited adequate mechanical and thermal properties. In contrast, plasticized TPS with glycerol:malic acid (1:1) showed lower thermal stability and a pasty and sticky behavior, indicating that malic acid accelerates degradation of starch during processing.

Polylactic acid and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) nano and microparticles for packaging bioplastic composites

Two methods, nanoprecipitation and emulsification/solvent evaporation with different solvents, to prepare nano and microparticles of polylactic acid (PLA) and PHBV are investigated. The obtained particles are characterized in terms of morphology by SEM and thermal properties by DSC and TGA. The objective is the preparation of PLA and PHBV nano and microparticles, with controlled shape and size distribution, for their further inclusion into biopolymer matrices such as PLA, PHBV or thermoplastic starch matrices. The purpose is the use of these biocomposites in the sector of wrapping and packaging. Good thermal properties of the nano and microparticles are important to the posterior processing as extrusion film technique. Although the smallest particles are obtained for PLA using nanoprecipitation technique with THF as solvent, these nanoparticles show a low thermal stability. The emulsification technique using dichloromethane as solvent shows to be a good option to obtain, for PLA and PHBV, spherical particles with controlled size and adequate thermal stability. The reproducibility of the selected method is studied for up-scaling nano and microparticle production to pre-industrial level. This study of reproducibility using statistical analysis shows the robustness of the methodology.