Influence of Citric Acid and Curing Time on Water Uptake

Abstract:

Starch is highly promising biopolymer for the production of packaging material since it gives films a good tensile and gas barrier properties. However, non-plasticized starch films are brittle and their hydrophilic character results in poor moisture barrier properties and high water sensitivity. In order to improve films formation and material properties of starch, plasticization and chemical modification such as cross-linking of the starch is required. The cross-linking reaction able to improve thermal stability, tensile strength and decreased the dissolution of starch films in water and formic acid. From the study, the percentage of water uptake reduced when the blending ratio of citric acid increased.The percentage of water uptake highly affected by curing time compared to blending ratio. Increasing the curing time from 1 hour to 2 hour significantly reduced the percentage of water uptake. At 4 hour curing time, the percentage water uptake reached equilibrium faster than 3 hour curing time. This shows that more citric acid molecules were chemically bonded with the starch chains, resulting in higher cross link degree and thus, reduced the percentage of water uptake.

• Periodical: Applied Mechanics and Materials (Volume 625)
• Pages: 123-126
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.625.123
• Online since: September 2014
• Authors: Sohibatul Muizzah Mohamad Izhar*, Ku Zilati Ku Shaari, Zakaria Man, Yon Norasyikin Samsudin
• Keywords: Citric Acid, Cross-Link, Curing Time, Starch, Water Uptake

References

[1] X. Z. Tang and S. & Alavi, Recent advances in starch, polyvinyl alcohol based polymer blends, nanocomposites and their biodegradability, Carbohydrate Polymers, vol. 85, pp.7-16, (2011).

DOI: 10.1016/j.carbpol.2011.01.030

[2] C. Menzel, E. Olsson, T. S. Plivelic, R. Andersson, C. Johansson, R. Kuktaite, L. Järnström and K. Koch, Molecular structure of citric acid cross-linked starch films, Carbohydr. Polym., vol. 96, pp.270-276, 7/1, (2013).

DOI: 10.1016/j.carbpol.2013.03.044

[3] R. Shi, Z. Zhang, Q. Liu, Y. Han, L. Zhang, D. Chen and W. Tian, Characterization of citric acid/glycerol co-plasticized thermoplastic starch prepared by melt blending, Carbohydr. Polym., vol. 69, pp.748-755, 7/2, (2007).

DOI: 10.1016/j.carbpol.2007.02.010

[4] H. Park, S. Chough, Y. Yun and S. Yoon, Properties of starch/PVA blend films containing citric acid as additive, Journal of Polymers and the Environment, vol. 13, pp.375-382, (2005).

DOI: 10.1007/s10924-005-5532-1

[5] E. Olsson, M. S. Hedenqvist, C. Johansson and L. Järnström, Influence of citric acid and curing on moisture sorption, diffusion and permeability of starch films, Carbohydr. Polym., vol. 94, pp.765-772, 5/15, (2013).

DOI: 10.1016/j.carbpol.2013.02.006

[6] B. Ghanbarzadeh, H. Almasi and A. A. Entezami, Improving the barrier and mechanical properties of corn starch-based edible films: Effect of citric acid and carboxymethyl cellulose., Industrial Crops and Products, vol. 33, pp.229-235, (2011).

DOI: 10.1016/j.indcrop.2010.10.016

[7] L. T. Sin, W. A. W. A. Rahman, A. R. Rahmat and M. I. Khan, Detection of synergistic interactions of polyvinyl alcohol–cassava starch blends through DSC, Carbohydr. Polym., vol. 79, pp.224-226, 1/5, (2010).

DOI: 10.1016/j.carbpol.2009.08.003

[8] N. Tudorachi, C. N. Cascaval, M. Rusu and M. Pruteanu, Testing of polyvinyl alcohol and starch mixtures as biodegradable polymeric materials, Polymer Testing, vol. 19, pp.785-799, (2000).

DOI: 10.1016/s0142-9418(99)00049-5

[9] A. Sarwono, Z. Man and M. A. Bustam, Improvement of Hydrophobicity of Urea Modified Tapioca Starch Film with Lignin for Slow Release Fertilizer, Advanced Materials Research, vol. 626, pp.350-354, (2012).

DOI: 10.4028/www.scientific.net/amr.626.350