EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Chitin is the second most abundant polysaccharide in the world after cellulose. It is obtained from molluscs, shrimps, and insect shells. Chitin possesses a semicrystalline structure and has been identified in the literature as a piezoelectric system[1,2]. Nevertheless, chitin's low solubility makes it difficult to use in various applications leaving its derivative, chitosan (obtained by chitin deacetylation), as easier manipulating material with better mechanical characteristics for free-standing membranes. The electromechanical response of chitosan has been reported in the literature[3]. However, there is little knowledge about its piezoelectric properties, so a better understanding of this information is needed. The clear electromechanical characterization of chitosan will be useful for biomedical applications, considering the already known antibacterial, non-toxic and biocompatibility advantages.

In this work, we present a systematic characterization of chitosan films fabricated with different acids and amounts of plasticizer, intending to understand the influence of structural modifications on the mechanical performance and consequently on the electromechanical response. Structure modification on the chitosan films was analysed using XRD and FTIR. The thermal response was obtained by TGA and DSC, and the mechanical behaviour was analysed by the tensile until rupture test. The electromechanical response at low frequencies was measured by a vibration-setup and dielectric response was obtained from LCR meter measurements.
The structural characterization suggests that the addition of 50 wt% of glycerol increases the semicrystallinity of the films, the mechanical measurements show that the lactic acid increases elasticity and stretchability of pristine films by ~16%, and the addition of glycerol increases these properties by ~93%. Thermal stability improved with the presence of the plasticizer; electromechanical response increases by 50% with the higher glycerol concentration. The results suggest a high correlation between physical and mechanical properties with the electric performance of the films, highlighting the main variables to modify for further application development.