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Fabrication and Characterization of Polyethylene/Thermoplastic Starch Nanocomposite Films Containing Ethylene Adsorbent Nanostructures for Atmosphere-Controlled Packaging

Sharifi, Mina | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53793 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Bagheri, Reza; Pircheraghi, Gholamreza
  7. Abstract:
  8. In this research, a polyethylene / thermoplastic film containing ethylene adsorbent nanostructure was fabricated to package agricultural products and increase the shelf life of fruits and vegetables. The thermoplastic starch containing 60 wt% starch and 40 wt% plasticizers with weight ratios of 5: 1, 4: 1, and 3: 1 sorbitol to glycerol was added to the polyethylene film to determine the composition of the final film. The film was prepared by a combination of low-density polyethylene with 10wt % linear low-density polyethylene, 30 wt% thermoplastic starch (4: 1 sorbitol to glycerol ratio), and 3wt% PE-g-MA as compatibilizer. Then, halloysite nanotubes were added to the film as ethylene adsorbent nanostructure in amounts of 1, 3, and 5 wt% naturally and alkali-treatment with 5M sodium hydroxide solution. Samples of natural and alkali-treatment halloysite nanotube powder were analyzed by FT-IR and BET in order to compare the effect of alkaline modification on surface hydroxyl groups and total nanotube pore volume. Also, gas chromatography-mass spectrometry analysis was used to measure the adsorption capacity of ethylene by halloysite nanotube powder in the raw and alkali-treatment state, and it was observed that the adsorption capacity of the modified powder increased up to 3 times compared to the natural state. To evaluate the mechanical properties of the prepared films, tensile tests and Elmendorf tear resistance test were used. Also, FE-SEM electron microscope was used to examine the surface microstructure of the, and the DSC test was used to examine the thermal properties. Finally, film samples containing 5wt% halloysite nanotubes were used for packaging and storing green bananas for 20 days at room temperature. By comparing the discoloration of bananas at 5-day intervals, it was observed that film samples containing alkali-treatment and raw halloysite nanotubes increased the shelf life of bananas by five and more than ten days, respectively, compared to control film packaging
  9. Keywords:
  10. Halloysite ; Ethylene Adsorbent ; Polyethylene/Thermoplastic Starch Blend ; Packaging Film ; Packaging ; Shelf Life ; Agricultural Products

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