Filtreler

2002 - 20062
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Ayarlar

Yazar: Pekcan, Mehmet Önder × Konu: Energy transfer ×

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Listeleniyor 1 - 2 / 2
  • Küçük Resim
    Yayın
    Monitoring diffusion of reptating polymer chains by a direct energy transfer method: A Monte Carlo simulation
    (Wiley-Blackwell, 2002-07-29) Tüzel, Erkan; Kısacıkoğlu, Kemal Batuhan; Pekcan, Mehmet Önder
    A kinetic Monte Carlo method was used to simulate the diffusion of reptating polymer chains across an interface. A time-resolved fluorescence technique in conjunction with a direct energy transfer method was used to measure the extent of diffusion of dye-labeled reptating polymer chains. The diffusion of donor- and acceptor-labeled polymer chains between adjacent compartments was randomly generated. The fluorescence decay profiles of donor molecules were simulated at several diffusion steps to produce mixing of the polymer chains. Mixing ratios of donor- and acceptor-labeled polymer chains in compartments were measured at various stages (snap-shots) of diffusion. It was observed that for a given molecular weight, the average interpenetration contour length was found to be proportional to the mixing ratio. Monte Carlo analysis showed that the curvilinear diffusion coefficient is inversely proportional to the weight of polymer chains during diffusion.
  • Küçük Resim
    Yayın
    Effects of annealing on morphology of polymer/polymer (PS/PMMA) blend; a fluorescence study
    (John Wiley& Sons Inc, 2006-05-05) Uğur, Şaziye; Pekcan, Mehmet Önder
    Steady state fluorescence (SSF) technique conjunction with optical microscopy were used to study the morphology of polystyrene (PS)/poly(methyl methacrylate) (PMMA) blend upon annealing above glass transition in elevated time intervals. The PS/PMMA blends were prepared from dissolution of pyrene (P) and naphthalene (N) labeled PS and PMMA particles, respectively. Monte Carlo Simulations were performed to model the N and P fluorescence intensities (I-N and I-P), Using photon diffusion theory. Number of N and P photons (N-N and N-P) emerging from the front surface of the blend are calculated when only N is excited, where N-P photons are combined of photons from radiative (N-PR) and nonradiative (N-PNR) energy transfer processes. Optical microscopy images were taken at each annealing step to Support Our findings from fluorescence measurements.