resumo
Antibacterial thermoplastic starch-chitosan based materials were successfully prepared by melt-mixing. The effect of chitosan modification (quaternization and grafting of long carbon chains) on the properties of the materials was also studied. All the ensuing materials were characterized in terms of thermal stability, crystalline structure, mechanical performance, and antibacterial activity. The incorporation of chitosan and its derivatives into the thermoplastic starch matrices resulted in an increment in tensile strengths (up to 85%); however for higher chitosan contents (5 and 7.5 wt.%), a decrease on the Young's modulus (around 50%) was observed, together with an increment in the elongation at break, which can be attributed to the prevention of the retrogradation process. Finally, the thermoplastic starch materials incorporated with 7.5 wt% of the unmodified chitosan and of the water-soluble chitosan derivative had partial (about 20% reduction of CFU) and total bactericidal effect against S. aureus.
palavras-chave
MECHANICAL-PROPERTIES; FILMS; BARRIER
categoria
Materials Science
autores
Tome, LC; Fernandes, SCM; Sadocco, P; Causio, J; Silvestre, AJD; Neto, CP; Freire, CSR
nossos autores
Armando Jorge Domingues Silvestre
Professor Catedrático
Carlos Pascoal Neto
Diretor do Raiz
Carmen Sofia da Rocha Freire Barros
Investigador Coordenador
Liliana C. Tomé
Estudante de doutoramentoProjectos
agradecimentos
FCT (Fundacao para a Ciencia e Tecnologia) is acknowledged for Liliana C. Tome (PhD research grant SFRH/BD/72830/2010) and for Susana C. M. Fernandes (Postdoctoral research grant SFRH/BPD/70119/2010), and for financial support through the Projects PTDC/QUI/68472/2006, Convenio FCT-CAPES 2010 and CICECO (Pest-C/CTM/LA0011/2011). The authors would also like to thank Prof. Aprigio Curvelo of the Instituto de Quimica de Sao Carlos for his experimental support with thermal analysis and mechanical experiments.