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PLA/PVAc Nano-Blends for Barrier Films: Effect of Gamma Irradiation

Razavi, Mohammad | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41419 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Forounchi, Massoud; Dadbin, Susan
  7. Abstract:
  8. Oxygen barrier properties of poly (lactic acid) (PLA) films were improved by blending it with hydrolyzed poly (vinyl acetate). Poly (vinyl acetate-co-vinyl alcohol) with vinyl alcohol contents of 0, 5, 10 and 15% was prepared using acid-catalyzed hydrolysis of poly (vinyl acetate). The Blend films of PLA/poly (VAc-co-VA) containing 0, 5, 10 and 15% of the copolymer with various degree of hydrolysis was prepared by solution-casting method. Effect of gamma irradiation on the films was examined by exposing them to radiation doses of 0, 20, 35 and 50 kGy. The films remained colorless and transparent after irradiation. Morphology of the samples characterized by optical microscopy displayed not much difference between the pristine poly (lactic acid) and blended film. Complete phase miscibility was observed for the PLA/ poly (VAc-co-VA) 85/15 and 95/5 films containing 5 and 15 percent of vinyl alcohol, as verified by dynamic mechanical analysis. Incorporation of poly (VAc-co-VA) 90/10 up to 15 wt% improved elongation at break of the films significantly. All samples exposed to gamma irradiation exhibited lower tensile strength and elongation at break indicating some chain scission. Oxygen barrier property of poly (lactic acid) films was enhanced upon blending with poly (vinyl acetate-co-vinyl alcohol). This was more noticeable at higher vinyl alcohol contents. On the other hand, gamma irradiation reduced the barrier properties of the samples due to more free volume created by chain scission effect. No significant changes were observed in the FTIR spectra of the PLA/poly (VAc-co-VA) and gamma irradiated films compared to that of the PLA film
  9. Keywords:
  10. Polylactic Acid ; Polyvinylacetate ; Gamma Irradiation ; Miscibility ; Barrier Properties

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