Characteristics of starch-based films with different amylose contents plasticised by 1-ethyl-3-methylimidazolium acetate. (20th May 2015)

• Record Type: Journal Article
• Authors: Xie, Fengwei; Flanagan, Bernadine M.; Li, Ming; Truss, Rowan W.; Halley, Peter J.; Gidley, Michael J.; McNally, Tony; Shamshina, Julia L.; Rogers, Robin D.
• Is Part Of: Carbohydrate polymers. Volume 122(2015)
• Page Start: 160
• Page End: 168
• Publication Date: 2015-05-20
• Subjects: Starch -- Ionic liquid -- 1-Ethyl-3-methylimidazolium acetate -- Plasticisation -- Amylose/amylopectin ratio -- Relative humidity; Starch (PubChem CID: 24836924) -- Water (PubChem CID: 962) -- Glycerol (PubChem CID: 753) -- 1-Ethyl-3-methylimidazolium acetate (PubChem CID: 11658353); Polysaccharides -- Periodicals; Polysaccharides -- Periodicals; Polysaccharides -- Périodiques; Electronic journals; 547.78
• DOI: 10.1016/j.carbpol.2014.12.072
• Languages: English
• ISSNs: 0144-8617

Abstract

Highlights: An ionic liquid, [Emim][OAc], was used to make plasticised starch-based materials. [Emim][OAc] made the starch structural effect (amylose/amylopectin) insignificant. [Emim][OAc] had a strong plasticisation effect on regular and high-amylose starches. The material characteristics were mainly affected by its moisture content. The moisture content had a great impact on the mechanical properties and electro-conductivity. Abstract: Starch-based films plasticised by an ionic liquid, 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]), were prepared by a simple compression moulding process, facilitated by the strong plasticisation effect of [Emim][OAc]. The effects of amylose content of starch (regular vs. high-amylose maize) and relative humidity (RH) during ageing of the samples on a range of structural and material characteristics were investigated. Surprisingly, plasticisation by [Emim][OAc] made the effect of amylose content insignificant, contrary to most previous studies when other plasticisers were used. In other words, [Emim][OAc] changed the underlying mechanism responsible for mechanical properties from the entanglement of starch macromolecules (mainly amylose), which has been reported as a main responsible factor previously. The crystallinity of the plasticised starch samples was low and thus was unlikely to have a major contribution to the material characteristics, although the amylose content impacted on the crystalline structure and the mobility of amorphous parts in the samples to some extent. Therefore, RH conditioning and thus the sample water content was the major factor influencing the mechanical properties, glass transition temperature, and electrical conductivity of the starch films. This suggests the potential application of ionic liquid-plasticised starch materials in areas where the control of properties by environmental RH is desired.