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Effect of cellulose nanocrystal and polyvinyl alcohol on the physical properties of starch based bionanocomposite films
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N Noushirvani   , B Ghanbarzadeh * , AA Entezami |
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Abstract: (15500 Views) |
| Background and Objective: Starch-based biopolymer films have disadvantages such as poor mechanical and barrier properties against water vapour that restrict their application in packaging. To improve the properties of starch-based films, different methods such as blending with other polymers and adding nanofillers have been suggested. Cellulose nanocrystals (NCC) are a suitable candidate for reinforcing starch biopolymers due to their biodegradability, nontoxicity, abundance in nature, low price, and renewability. The objectives of the current research were to investigate the effects of NCC and polyvinyl alcohol (PVA) on the properties of starch-based films to improve their mechanical and barrier properties.
Materials and Methods: NCC was produced from cotton linter and added to the starch-PVA film-forming blend. Tests used to determine the properties of the films thus produced included mechanical, water- vapour permeability, thermal property, X-ray diffraction (XRD), and transmittance electron microscopy (TEM) tests.
Results: Addition of PVA and NCC to film-forming solutions caused an increase in the maximum tensile stress (UTS) and a decrease in water-vapour permeability and solubility of the nanobiocomposit films. In addition, the XRD test showed that the 2 components − polymer matrix and nanofiller – were well dispersed in the blend. The optimum structure was observed at a concentration of 10% NCC.
Conclusion: Polyvinyl alcohol has OH groups and, hence, it can form hydrogen bonds with the starch OH groups, resulting in enhanced mechanical strength of polymer and improved mechanical and barrier properties of the biocomposite produced. Due to their high crystalline structure (as a result, high rigidity and elastic modulus) and their ability to form strong hydrogen bonds with starch and PVA, cellulose nanocrystals can potentially improve the mechanical and barrier properties of starch-based bionanicomposite films. The starch-based nanocomposites showed the highest UTS at a concentration of 10% NCC. At higher concentrations the UTS decreased, which could be attributed to aggregation of NCC in the polymer matrix. Aggregation of NCC at a level of 15% or 20% was observed as shown by XRD pattern peaks.
Keywords: Starch, Cellulose nanocrystal, Polyvinyl alcohol, Physical properties |
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| Keywords: Starch, Cellulose nanocrystal, Polyvinyl alcohol, Physical properties |
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Full-Text [PDF 716 kb]
(7215 Downloads)
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Article type: Research |
Subject:
nutrition
Received: 2012/02/26 | Published: 2012/04/15
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