title: Influence of alkali metal cations on the thermal, mechanical and morphological properties of rectorite/chitosan bio-nanocomposite films.
abstract: The main theme of this work is to study the influence of ion-exchangeable alkali metal cations, such as: Li(+), Na(+), K(+), and Cs(+) on the thermal, mechanical and morphological properties. In this regard, a set of rectorite/chitosan (REC-CS) bio-nanocomposite films (BNCFs) was prepared by facile reaction of chitosan with ion-exchanged REC clay. The microstructure and morphology of BNCFs were investigated with XRD, TEM, SEM and AFM. Thermal and tensile properties of BNCFs were also investigated. As revealed from TEM and XRD results, the BNCFs featured a mixed morphology. Some intercalated clay sheets, together with nano-sized clay tactoids were obtained in LiREC/CS, NaREC/CS and KREC/CS of the BNCFs. From fractured surface study, via SEM, it was observed that the dispersion of chitosan polymer attaches to (and covers) the clay platelets. FTIR confirmed strong hydrogen bonds between clay and chitosan polymer. In addition, the thermal stabilities significantly varied when alkali metal cations varied from Li(+) to Cs(+). The BNCFs featured high tensile strengths (up to 84 MPa) and tensile moduli (up to 45 GPa). After evaluating these properties of BNCFs, we came to conclusion that these bio-nano composites can be used for packaging applications.
authors.affiliation: Department of Polymer Technology, Tshwane University of Technology, CSIR Campus, Pretoria, South Africa.
authors.forename: A
authors.initials: A
authors.lastname: Babul Reddy
authors.affiliation: Department of Polymer Technology, Tshwane University of Technology, CSIR Campus, Pretoria, South Africa; DST/CSIR Nanotechnology Innovation Centre, National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria 0001, South Africa.
authors.forename: J
authors.initials: J
authors.lastname: Jayaramudu
authors.affiliation: Department of Polymer Technology, Tshwane University of Technology, CSIR Campus, Pretoria, South Africa; Department of Applied Chemistry, University of Johannesburg, Doornfontein 2028, South Africa.
authors.forename: G
authors.initials: G
authors.lastname: Siva Mohan Reddy
authors.affiliation: Department of Polymer Technology, Tshwane University of Technology, CSIR Campus, Pretoria, South Africa.
authors.forename: B
authors.initials: B
authors.lastname: Manjula
authors.affiliation: Department of Polymer Technology, Tshwane University of Technology, CSIR Campus, Pretoria, South Africa. Electronic address: SadikuR@tut.ac.za.
authors.forename: E R
authors.initials: ER
authors.lastname: Sadiku
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D002412:Cations / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry*; D000077215:Clay; D006860:Hydrogen Bonding; D008672:Metals, Alkali / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D008903:Minerals / Q000737:chemistry*; D053761:Nanocomposites / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D000538:Aluminum Silicates; D002412:Cations; D008672:Metals, Alkali; D008903:Minerals; D011108:Polymers; C546376:rectorite; D048271:Chitosan; D000077215:Clay
keywords: Alkali metals; Chitosan; Nanocomposite films; Rectorite; Thermal properties; X-ray diffraction