Biopolymer composite materials with antimicrobial effects applied to the food industry

MARÍA PAULA GUARÁS; VERA ALVAREZ; LEANDRO N. LUDUEÑA

Barcelona

Congreso; PDFA: Polymers, Design, Function and Application,; 2018

The use of starch as a raw material for the manufacturing of biodegradable products has been studied intensively in recent times. Due the hydrophilic nature of starch, products are sensitive to changes in ambient humidity and have poor mechanical properties. If stored under controlled conditions, mechanical properties have been observe to change, and were found that are correlated with changes in crystallinity. Researchers investigated strategies to improve thermoplastic starch properties, including chemical modifications and nano-reinforcements. Chemical modification by esterification produces a side growth of starch chains and improves the thermoplastic property of the 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.