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Preparation of Porous PVA Nanocomposite Hydrogels Via Gamma Irradiation

Sabourian, Parinaz | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46226 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Frounchi, Masoud; Dadbin, Susan
  7. Abstract:
  8. In this research, porous polyvinyl¬ alcohol (PVA)/Montmorillonite nanoclay and polyvinyl alcohol/polyvinyl pyrrolidone (PVP)/Montmorillonite nanoclay nanocomposite sponges (foams) were fabricated by freeze-drying method. The foams were crosslinked using gamma irradiation. The pore size and interconnectivity of nanocomposites characterized by scanning electron microscopy (SEM), showed bimodal pore size distribution resulting from preparation method.
    SEM micrographs displayed that addition of PVP ( wt% of total solid polymer) to the PVA sponges increased the pore size and interconnectivity, due to the optimal number of hydrogen bonds between functional groups of polymeric matrices. Differential scanning calorimetry (DSC) results showed that PVA/PVP sponges were more flexible than PVA sponges because of lower degree of crystallinity in PVA/PVP.
    On the other hand, SEM images showed that incorporation of nanoclay increase the number of pores due to more air bubbles trapped during mixing in presence of clay nanoparticles. The results obtained from tensile testing showed improvement in tensile strength and elongation at break of the nanocomposite sponges upon addition of wt% Montmorillonite nanoclays, but Young’s modulus of nanocomposites decrease by using mechanical mixing and increase without it. DSC results indicated that both PVP and nanoclay will decrease degree of crystallinity of polymeric sponges due to the hydrogen bonds of PVA/PVP and interactions between polymeric matrices and clay nanolayers. Polymeric sponges with specific compositions irradiated at the dose of and kGy absorbed water up to times of their initial weights as it was verified by equilibrium water content test.
    Fourier transform infrared (FTIR) spectra displayed that broadening of the peak corresponding to the hydroxyl group implying hydrogen bonds between functional groups of PVA and PVP. Intensity of the peak of hydroxyl group decreased due to the formation of cross-links between the chains of PVA/PVP.
    These nanocomposite sponges have the potential use in Lasic eye surgery and other biomedical applications.
  9. Keywords:
  10. Poly Vinyl Alcohol ; Polyvinylpyrolidon ; Montmorillonite ; Nanoclay ; Freeze Drying Method ; Gamma Irradiation ; Porous Hydrogel ; Medical Nanocomposite Sponge

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