Effects of various clay and plasticizers on the structure and properties of thermoplastic starch/clay nanocomposites

• Main Authors: Yao-Yu Hsu, 許耀宇
• Other Authors: Li-Hsiang Perng
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/2mpfh8

碩士 === 國立臺灣海洋大學 === 食品科學系 === 101 === The structure and properties of thermoplastic starch (TPS)/clay nanocomposites prepared by melt intercalation and determined by intercalation of TPS which in turn is affected by clay hydrophilicity and plasticizers. Additive of urea or formamide increased the degree of clay dispersion more than glycerol and could form exfoliated nanocomposites in TPS/Na+ montmorillonite (Na+MMT) and TPS/citric acid-activated montmorillonite (CMMT) nanocomposites. Higher Tg and tensile strength, lower water vapor permeability were also observed. The plasticizers did not react with starch at kneading process. The order of hydrogen bond-forming potential with starch was formamide > glycerol > urea, additive of formamide could effectively restrain the retrogradation of TPS more than glycerol or urea. Addition of Na+MMT or chitosan-modified montmorillonite (CSMMT) affects the hydrogen bond between starch and plasticizer negatively. Transmission electron microscopy image showed that the starch and CSMMT could form phase separated composite, so that the incorporation of CSMMT did not improve the mechanical properties or water vapor permeability of TPS/CSMMT composites. Clay in composites increased opacity and reduced its biodegradable rate. However, plasticizers have no apparent effect on opacity or biodegradability. Both plasticizers and clay showed influence on clay dispersion in TPS/clay composites. Plasticizers with amide groups enhanced the mechanical properties and water vapor permeability of composites which was beneficial in application of packaging material. The CMMT in TPS exhibited less reinforcement than Na+MMT which is caused by plasticizing effect of citric acid in TPS. In order to improve the tensile strength and water vapor permeability of TPS/CMMT nanocomposites, the content of the three plasticizers must be reduced. Dispersion of CSMMT in composite depends on the content of clay. The content of CSMMT additive must be less than 6 wt% to avoid aggregation of CSMMT.