Characteristics of starch-based films plasticised by glycerol and by the ionic liquid 1-ethyl-3-methylimidazolium acetate: A comparative study

Abstract

This paper reports the plasticisation effect of the ionic liquid, 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]), as compared with the traditionally used plasticiser, glycerol, on the characteristics of starch-based films. For minimising the additional effect of processing, a simple compression moulding process (which involves minimal shear) was used for preparation of starch-based films. The results show that [Emim][OAc] was favourable for plasticisation, i.e., disruption of starch granules (by scanning electron microscopy), and could result in a more amorphous structure in the starch-based materials (by X-ray diffraction and dynamic mechanical analysis). (13)C CP/MAS and SPE/MAS NMR spectroscopy revealed that not only was the crystallinity reduced by [Emim][OAc], but also the amorphous starch present was plasticised to a more mobile form as indicated by the appearance of amorphous starch in the SPE/MAS spectrum. Mechanical results illustrate that, when either glycerol or [Emim][OAc] was used, a higher plasticiser content could contribute to higher flexibility. In spite of the accelerated thermal degradation of starch by [Emim][OAc] as shown by thermogravimetric analysis, the biodegradation study revealed the antimicrobial effect of [Emim][OAc] on the starch-based materials. Considering the high-amylose starch used here which is typically difficult to gelatinise in a traditional plasticiser (water and/or glycerol), [Emim][OAc] is demonstrated to be a promising plasticiser for starch to develop "green" flexible antimicrobial materials for novel applications.

Effect of Plasticizer Type and Concentration on Tensile, Thermal and Barrier Properties of Biodegradable Films Based on Sugar Palm (Arenga pinnata) Starch

“…Thus, starch has attracted a great deal of interest as a potential alternative to conventional plastics for packaging applications. Several studies have investigated the development and characterization of starch based films from corn [4,[6][7][8], potato [9][10][11][12][13], cassava [14][15][16][17][18][19][20], banana [21], yam [22,23], pea [1], sago [24][25][26], rice [27][28][29][30], maize [31][32][33][34], Kudzu [35] and agar [36][37][38][39]. According to Sahari et al [40] sugar palm starch is also a potential biopolymer material for making biodegradable films.…”

Highly functional green materials platform: Starch-ionic liquid-carbon nanotube polymer melt nanocomposites

“…It is also reported in this article that the maximum conductance that TPS plasticized by [Amim]Cl can achieve is 10 -1.6 S cm -1 at 14.5 wt% water content, which means IL can also broaden the application of TPS film. TPS processed by extruders utilising IL as plasticiser has been reported in another study (Sankri et al, 2010 (Xie et al, 2014). This showed that the combined plasticisers contribute to a significant reduction in granule remnants compared with glycerol, resulting in highly amorphous structure.…”

“…Other strong peaks at 2θ of 7°, 13°, 20° and 22°, which overlaps with 23°, are indicative of a V-type crystalline structure (Xie et al, 2014). The diffractogram of RMS-E9-RH75 shows a similar pattern, however with lower intensity.…”

“…As displayed in figure 4-4, figure 4-5 and , Xie et al, 2014. In these studies, it was suggested that the reduced sample strength and stiffness was due to the hydrogen bonding disruption with the -OH sites of starch by plasticiser.…”

“…RMS-E9-RH0 shows obvious peaks at 2θ of 15°, 23° and a doublet at 17° and 18°, which are evidence of the A-type crystalline structure (Cheetham and Tao, 1998, Lopez-Rubio et al, 2008, Xie et al, 2014. Other strong peaks at 2θ of 7°, 13°, 20° and 22°, which overlaps with 23°, are indicative of a V-type crystalline structure (Xie et al, 2014).…”