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Investigations of chitin- and cellulose-based materials Winnick, Rebecca

Abstract

Chitin plastic was fabricated from Dungeness crab shells. Chitin was purified from the shells, deacetylated, and then formed a gel in weak acid. The gel was poured into molds and then dried to leave behind a plastic film, which was strengthened by treatment with sodium hydroxide. Scanning electron microscopy (SEM) images of the dried film indicated that it adopts a layered structure. One sample batch was deacetylated for eight hours, and the other for twelve hours. The batch deacetylated for eight hours had superior characteristics, with a tensile strength of 93 ± 35 N/mm² and maximum strain of (7.5 ± 3) % while dry; after soaking in water for an hour, the tensile strength decreased to 7 ± 7 N/mm² and the strain at fracture increased to (31 ± 9) %. Contact angle experiments showed that the material is hydrophobic. Infrared (IR) spectroscopy confirmed a high degree of deacetylation in the final material. Results from IR spectroscopy and X-ray diffraction suggest a low degree of crystallinity in the material. This strong and waterproof chitin bioplastic is promising for use as packaging and for medical technology. Additionally, a new type of polypyrrole-cellulose composite was developed. Polypyrrole was synthesized, mixed with an aqueous suspension of cellulose nanocrystals, and dried to a homogeneous black iridescent film. The film showed iridescence that is attributed to the chiral nematic structure characteristic of cellulose nanocrystal films. Surprisingly, the film was not found to have any conductive or capacitative electrical properties. When doped, these new composite materials could have interesting electrical properties owing to the chiral structure of the films.

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Attribution-NonCommercial-NoDerivatives 4.0 International

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