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Yayın A photon transmission study for film formation from poly(vinyl acetate) latex particles with different molecular weights(John Wiley & Sons Inc, 2007-10-15) Arda, Ertan; Kara, Selim; Pekcan, Mehmet ÖnderThe photon transmission technique was used to monitor the temperature evolution of film formation from poly(vinyl acetate) (PVAc) latex particles with two different molecular weights. Two sets of latex films were prepared below the glass transition temperature (T-g) of PVAc, which are named as low (LM) and high molecular weight (HM) films. These films were annealed at elevated temperatures above the Tg of PVAc for various time intervals. It is observed that transmitted photon intensity (I-tr) from these films increased as the annealing temperature was increased. Onset temperatures (T-H) at given times (tau H) for starting the optical clarity of LM and HM films were measured and used to calculate the healing activation energies (Delta H) for the PVAc minor chains, and found to be as 28.1 kcal/mol and 27.7 kcal/mol, respectively. The increase in the transmitted photon intensity, Itr above TH was attributed to the increase in the number of disappeared interfaces between the deformed latex particles. Prager-Tirrell (PT) model was employed to interpret the increase in the crossing density of chains at the junction surfaces. The interdiffusion (backbone) activation energies (Delta E) were measured and found to be 177.5 kcal/mol and 210.7 kcal/mol for a diffusing PVAc chains across the junction surface of LM and HM latex films, respectively.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 ÖnderSteady 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.Yayın Film formation from nano-sized polystyrene latex particles(John Wiley & Sons Ltd, 2005-05) Uğur, Şaziye; Elaissari, Abdelhamid; Pekcan, Mehmet ÖnderThis work reports on the steady state fluorescence (SSF) technique for studying film formation from surfactant-free, nano-sized polystyrene (PS) latex particles prepared via emulsion polymerization. The latex films were prepared from pyrene M-labeled PS particles at room temperature and annealed at elevated temperatures in 5, 10, 15, 20 and 30 min time intervals above the glass transition temperature (T-g) of PS. During the annealing processes, the transparency of the film was improved considerably. Monomer and excimer fluorescence intensities, I-p and I-E respectively, from P were measured after each annealing step to monitor the stages of film formation. Evolution of transparency of the latex films was monitored by using photon transmission intensity, It,. Void closure and interdiffusion stages were modeled and related activation energies were determined and found to be 10.3 and 50.3 kJ mol(-1). Void closure temperatures, T-v, were determined from the minima of I-tr value. CopyrightYayın Enhancing mechanical performance of FDM-printed ABS parts through annealing optimization(John Wiley and Sons Inc, 2025-06-18) Kösemen, Elifnur; Bakkal, Mustafa; Kuzu, Ali TanerThis study examines the impact of annealing on the mechanical properties of acrylonitrile butadiene styrene (ABS) parts produced using fused deposition modeling (FDM). The research investigates how different annealing temperatures (90°C, 105°C, and 120°C), production orientations (upright, on edge, and flat), and infill patterns influence hardness, tensile strength, and impact resistance. Experiments were conducted using a Stratasys F370 printer, and samples were tested following ISO standards for mechanical performance. Results indicated that annealing at 90°C and 105°C generally improved hardness, tensile strength, and impact resistance, particularly for upright and on-edge orientations. However, annealing at 120°C led to a decrease in these properties, likely due to microstructural changes observed through scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) analysis. The study highlights the importance of optimizing production parameters and annealing conditions to achieve desired mechanical properties in FDM-printed ABS parts. These findings may inform post-processing strategies for enhancing the reliability and performance of additive manufactured components, particularly for applications in industries utilizing ABS materials for customized and prototype parts.
