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  • Yayın
    Film formation from PS latex doped PNIPAM hydrogels at various heating and cooling rates
    (VSP BV, Brill Academic Publishers, 2008-05-01) Uğur, Şaziye; Yargı, Önder; Pekcan, Mehmet Önder
    Film formation from polystrene (PS) latex doped poly(N-isopropylacrylamide) (PNIPAM) hydrogels was studied by using photon transmission technique. The transmitted light intensity, It, was monitored during film formation process. Films were prepared by annealing, 10 wt% PS doped PNIPAM particles at five different heating and cooling rates at temperatures ranging from 10 to 100 degrees C. I-tr presented a hysteresis loops during heating-cooling cycles, which were explained by void closure and void reconstruction processes. The corresponding activation energies were measured during reversible film formation process. Void closure and void reconstruction models were introduced to produce the activation energies.
  • Yayın
    Reversible film formation from nano-sized PNIPAM particles below glass transition
    (Springer-Verlag, 2007-01) Uğur, Şaziye; Elaissari, Abdelhamid; Yargı, Önder; Pekcan, Mehmet Önder
    Reversible film formation process from nano-sized Poly(N-isopropylacrylamide) (PNIPAM) microgel particles were studied during heating-cooling cycles at various rates. Photon transmission technique was used and transmitted photon intensity I (tr) was monitored during heating-cooling cycles. The increase and decrease in I (tr) during heating and cooling was explained with the void closure and void reconstruction processes, and the corresponding activation energies were measured. It was observed that PNIPAM microgels required less energy during reconstruction of voids than their closure.