The Effect of Glycerol/Water and Sorbitol/Water on the Plasticization of Hydroxyethylacryl Chitosan/Sodium Alginate Films

Pitchaya Treenate,Masayuki Yamaguchi,Pathavuth Monvisade,J Zhou,O Adiguzel

doi:10.1051/matecconf/20153002006

Abstract

This research aimed to investigate on the effects of glycerol/water and sorbitol/water on the plasticization of hydroxyethylacryl chitosan (HC)/sodium alginate (SA) films. The HC/SA films were prepared with different amount of glycerol or sorbitol as a plasticizer (25, 40 and 50% w/w) and kept at different relative humidity (0% RH and 50% RH) in order to restrict the content of water within the films. The results from differential scanning calorimetry (DSC) showed the miscibility of polymer and plasticizers (glycerol and sorbitol) for all blend compositions. A remarkable reduction of glass transition temperature (T g ) could be obtained by adding glycerol over 40% w/w. For sorbitol plasticized films, although the addition of sorbitol could reduce T g , it was still higher than room temperature. It was claimed that glycerol could gain more effective plasticizing than sorbitol in the HC/SA films. In the cooperation with water as co-plasticizer (glycerol/water or sorbitol/water), the T g values of all films were dramatically decreased to -50 °C for glycerol/water plasticized films and down to 0 °C for sorbitol/water plasticized films. The reasonable flexible films could be obtained by the use of either glycerol/water or sorbitol/water as couple plasticizers.

Highlights

In recent years, polysaccharide films have been used to replace petroleum-based polymers owing to their biodegradability, renewability and non-toxicity
It could be recommended that the polymer and the plasticizer were miscible for all blend compositions
Higher plasticizer concentrations led to the change of the physical structure of the films by decreasing the intermolecular forces between the polymer chains, increasing the free volume, and increased the mobility of the polymer chains resulting in the lower values of Tg

Summary

Introduction

Polysaccharide films have been used to replace petroleum-based polymers owing to their biodegradability, renewability and non-toxicity. Among various kinds of the polysaccharides, chitosan (CS) and sodium alginate (SA) are interesting. Due to the strong antimicrobial activity of CS, many studies relating to the applications of CS based edible films have been reported [1,2,3]. The mixtures from the combination of CS and SA have been studied [7]. With regard to the film forming procedure, CS could not homogeneously blend with SA because they immediately form gel by ionic crosslinking between their structures. As this point, water-soluble hydroxyethylacryl chitosan (HC) was replaced

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Conclusion