Β-Chitin samples with similar microfibril arrangement change mechanical properties varying the degree of acetylation. (1st March 2019)

• Record Type: Journal Article
• Authors: Montroni, Devis; Fermani, Simona; Morellato, Kavin; Torri, Giangiacomo; Naggi, Annamaria; Cristofolini, Luca; Falini, Giuseppe
• Is Part Of: Carbohydrate polymers. Volume 207(2019)
• Page Start: 26
• Page End: 33
• Publication Date: 2019-03-01
• Subjects: Chitin -- Mechanical properties -- Acetylation degree -- Microfibril arrangement -- Molecular structure; Polysaccharides -- Periodicals; Polysaccharides -- Periodicals; Polysaccharides -- Périodiques; Electronic journals; 547.78
• DOI: 10.1016/j.carbpol.2018.11.069
• Languages: English
• ISSNs: 0144-8617

Abstract

Graphical abstract: Highlights: Samples of β-chitin with similar fibril organization have been prepared. Mechanical parameters were determined as function only of acetylation degree (DA). Maximum elongation increased decreasing the DA. Maximum stress and Young's modulus decreased reducing the DA. Mechanical parameters correlate to structural changes on molecular scale. Abstract: Chitin is widespread in nature and is increasingly used in synthetic process for the production of new biomaterials. Chitin degree of acetylation, crystalline structure and microfibril arrangement differentiate chemical, physical and mechanical properties. Nevertheless, no information are available on the relationship between the mechanical properties and the degree of acetylation (DA) in chitin samples in which the microfibril arrangement does not change. Here, samples of β-chitin with decreasing DA, up to chitosan, were prepared using the squid pen of Loligo vulgaris . These samples were characterized by CP-MAS NMR spectroscopy, scanning electron microscopy, thermal analyses, synchrotron X-ray fiber diffraction and tensile tests. The results showed a similar microfibril arrangement decreasing the DA, except for the chitosan sample. The mechanical properties showed an increase of the maximum strain and a reduction of the maximum stress and Young's modulus, decreasing the DA. These changes, not linear with the DA, were related to structural changes at molecular structure level. The knowledge deriving from this study is of interest both for the understanding of the mechanical properties of chitinous biological samples, but also for the design and synthesis of new biomacromolecular materials.