Effect of Glycerol on Water Vapor Sorption and Mechanical Properties of Starch/Clay Composite Films

Abstract

Plasticized starch/clay composite films were prepared by casting aqueous solutions containing oxidized corn starch, different concentrations of glycerol as a plasticizer and 5% clay (sodium montmorillonite, Na 1 -MMT) on the basis of dry starch. The waterbinding properties of the composite films were evaluated by water vapor sorption isotherms at room temperature and various relative humidities (RHs). Mechanical properties and abrasion resistance were also analyzed for the films with varying glycerol contents at 68% RH and room temperature. Changes in water sorption isotherms suggested that glycerol interacted with both water and starch in a complicated way. A saturation phenomenon of glycerol, depending on RH, was observed based on the isotherms. Above this saturation content, phase separation of the system occurred with the appearance of free glycerol. According to mechanical performance and abrasion resistance, as well as water vapor sorption of the starch blend films, the threestage transition was presented to be related to the state of glycerol in the blend system, i.e. adsorption of glycerol onto H-bonding sites of starch, supersaturation of glycerol as plasticizer and further supersaturation of glycerol. Only above the supersaturation content can glycerol play a plasticizer role in starch-based composites.

Influence of a Plasticizer on the Mechanical Properties of Kenaf-Filled Chitosan Bio-Composites

“…This action would make chitosan polymer chains and cellulose chains (as the main component of kenaf dust) to split under an applied load [16,17] . Consequently, Gy causes migration of the plasticizing action from itself to the chitosan and cellulose polymer chains.…”

Properties of water‐soluble acrylic copolymer/montmorillonite nanocomposites for warp sizing

“…(1), that is, the adhesional energy. Table I displays the results for the surface tension, contact angle, and corresponding adhesion work of the acrylic copolymer/MMT nanocomposites at 1 wt % concentration, along with specific adhesion, which was examined by the breaking force of lightly sized loosely twisted slubbing with a 1 wt % size paste, 11,12,16 the so-called roving method. From the results in Table I, we determined that the adhesion work of the size solution to the films of polyester and cellulose were all in the range 60-80 mJ/m 2 and increased gradually with increasing MMT content up to 3% and then decreased with increasing MMT content.…”

“…Abrasion resistance 16 The film was tested for abrasion resistance on a Y571L fabric rubbing apparatus (Laizhou Electron Instrument Co., Ltd., Laizhou, China). After it was equilibrated at 20 C and 65% RH for 1 week, the film was abraded 400 times with a grinding head covered with 600-mesh sand paper.…”

Effect of adding a small amount of high molecular weight polyacrylamide on properties of oxidized cassava starch

“…For the films made of starch alone, however, the semi-rigid characteristics of the molecular skeleton and strong intra-and inter-molecular hydrogen bonds result in brittleness (Ma & Yu, 2004) and poor processability of the films at low moisture content (Chen & Lai, 2008;Talja, Helén, Roos, & Joupplia, 2008;Yu, Wang, Wu, & Zhu, 2008). To overcome the shortcomings, starches and their derivatives are usually blended with various water-soluble polymers, especially with polyvinyl alcohol (PVA) for textile sizes (Jayasekara, Harding, Bowater, Christie, & Lonergan, 2004;Zhu, 2003).…”