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Carbohydr Polym. 2019 Feb 15;206:528-538. doi: 10.1016/j.carbpol.2018.11.034. Epub 2018 Nov 14.

Starch-zinc complex and its reinforcement effect on starch-based materials.

Author information

1
School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, China.
2
School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, China. Electronic address: hushanren@163.com.
3
Institute of Advanced Study, University of Warwick, Coventry CV4 7HS, United Kingdom; International Institute for Nanocomposites Manufacturing (IINM), WMG, University of Warwick, Coventry CV4 7AL, United Kingdom; School of Chemical Engineering, The University of Queensland, Brisbane, Qld 4072, Australia. Electronic address: f.xie@uq.edu.au.

Abstract

In this work, we found that ZnCl2 solution can not only be used as a plasticizer for starch but also provide a mechanical reinforcement effect to the resultant starch-based materials. By a one-step compression molding process, well-plasticized starch-based films could be obtained at 120 °C with a 15 wt.% ZnCl2 solution. Both the tensile strength and elongation at break of the films increased with a rise in ZnCl2 concentration, which demonstrates a mechanical reinforcement. This reinforcement could be mainly ascribed to the in-situ formed starch-zinc complexes and the enhanced starch molecular interactions. Moreover, if the processing method was changed into firstly mixing followed by compression molding, the tensile strength increased by more than three folds at no cost of the elongation at break. Regarding this, we propose that shear could further enhance the molecular interactions within the material. However, if the ZnCl2 concentration was too high, the mechanical properties were then reduced irrespective of the processing protocol, which could be due to the weakened molecular interactions by ZnCl2. Thus, we have demonstrated a new, simple method for preparing starch-based composite materials with enhanced mechanical properties, which could be potentially applied to many fields such as packaging, coating and biomedical materials.

KEYWORDS:

Mechanical properties; Plasticization; Reinforcement; Starch (PubChem CID: 24836924); Starch-based materials; Water (PubChem CID: 962); Zinc chloride (PubChem CID: 5727)

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