INTEMA   05428
INSTITUTO DE INVESTIGACIONES EN CIENCIA Y TECNOLOGIA DE MATERIALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Effect of storage time and moisture in properties of starch/bentonite nanocomposites
Autor/es:
ALVAREZ, VERA ALEJANDRA; LUDUEÑA, LEANDRO NICOLÁS; GUARÁS, MARÍA PAULA
Lugar:
Barcelona
Reunión:
Congreso; Polymer 2018: Design, function and application; 2018
Resumen:
Used of starch as a raw material for the manufacturing of biodegradable products has been studied intensively in recent times, with clear indications of the advantages and limitations imposed by the used of this raw material. Due the hydrophilic nature of starch, products are sensitive to changes of ambient humidity and have poor mechanical properties. If stored under controlled conditions, mechanical properties have been observe to change, and were found that be correlated with changes in crystallinity. Researchers investigated strategies to improved thermoplastic starch properties, including chemical modifications and introduced nano-reinforcements. Chemical modification by esterification produces a side growth of starch chains and improves the thermoplastic property of material. The introduction of ester groups, plays an internal plasticizing role and reduces the degree of starch crystallinity. Besides the ester group can improve the hydrophobicity of the starch-based materials. Biopolymer-clay nanocomposites are new materials with potentially improved mechanical and thermal properties. These composites are prepared by addition of low amounts of clay to biopolymer matrix. The main challenge for preparing nanocomposites with enhanced properties is the nanoscale dispersion of clay in the polymer matrix. To improve clay dispersion, organic cations can be used to exchange with the sodium ions residing in the interlayer of clay. The objective of this work was to prepare biodegradable TPS/organobentonite nanocomposites by melt intercalation using reactive extrusion technique. For this purpose, pristine bentonite was firstly exchanged with benzalkonium chloride. The resulting organobentonite was used as nano-reinforcement of thermoplastic starch matrix. The derivatization of starch was performed with maleic anhydride and once modified it was processed in the presence of a plasticizer in a twin screw extruder. The effect of clay modification on the morphology, thermal properties, water absorption, mechanical response and biodegradability of nanocomposites were studied as a function of store moisture and storage time.