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Poly (Lactic Acid)/Poly(Ethylene-Co-Vinyl Acetate) Nano-Composites as Packaging Films

Zaji, Mahdieh | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50824 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Frounchi, Masoud
  7. Abstract:
  8. The purpose of this project was to produce and examine the Poly(lactic acid)/poly(ethylene-co-vinyl acetate)/ nano-clay nanocomposite by solution casting that can be used for food packaging. In this study, it was observed that solvent evaporation at 4°C gives uniform films, without phase separation and free of voids, in a certain composition of polymers related to the rate of solvent evaporation.According to DMTA results Poly(lactic acid) and poly(ethylene-co-vinyl acetate) with 28% vinyl acetate, were compatible in less than 10% poly(ethylene-co-vinyl acetate) content in blend of them. Also, results of SEM tests showed that ethylene-co-vinyl acetate particle size in blends with 3 and 5 wt.% ethylene-co-vinyl acetate are smaller and interphase interactions between poly(ethylene-co-vinyl acetate) and Poly(lactic acid), as an important parameters in thermoplastic (Poly(lactic acid)) toughening with elastomers (poly(ethylene-co-vinyl acetate)), was better than blend with 7% poly(ethylene-co-vinyl acetate).The presence of 3% poly(ethylene-co-vinyl acetate) in Poly (lactic acid) resulted in an increase in elongation at break from 270 to 1225%, and a slight reduction in tensile strength from 24 to 23 MPa and the presence of 1 pph nanoclay in blend containing 3% poly(ethylene-co-vinyl acetate), led to a decrease in elongation at break to 901 % Compared to the blend and increased tensile strength to 25.5 MPa. Both Poly (lactic acid) and ethylene-co-vinyl acetate are able to intercalate nano clay, for a low amount of nanoclay,1 pph, a completely exfoliated structure, and for 3 pph, intercalated structure and a relatively exfoliated structure gained. Based on SEM, XRD and UV-Vis results, nanoparticles used in this study acted as compatibilizers for Poly (lactic acid) and ethylene-co-vinyl acetate. Clay nanoparticles, also acting as a nucleating agent, led to an increase in crystallinity as one of the parameters of nanocomposites with barrier properties
  9. Keywords:
  10. Nanocomposite ; Nanoclay ; Polylactic Acid ; Ethylene Vinyl Acetate (EVA) ; Polyethylene-co-vinyl Acetate

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