Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 51Citation - Scopus: 58Effect of Additives on Flexible Pvc Foam Formation(Elsevier Ltd., 2008) Demir, Hasan; Sipahioğlu, Muzaffer; Balköse, Devrim; Ülkü, SemraIn this study, effects of Ca/Zn stearate and organotin heat stabilizers and zeolite, CaCO3, cellulose and luffa flours fillers, and their concentrations (2.5, 5, 10 and 20% by weight) on production of flexible PVC foams by chemical blowing agent, azodicarbonamide were investigated. Foam morphology, foam density, compressive mechanical properties and water uptake capacities of samples were determined. Morphology of the sample without any filler showed that employment of Ca stearate and Zn stearate heat stabilizers instead of organotin stabilizers increases foam formation and decreases pore sizes and regularity in pore size distribution. Foams having organotin stabilizer were more resistant to heat than the ones with Ca/Zn stearate for long heating periods. Foams, including organotin-based heat stabilizers, have compact structure. It was observed that, samples containing zeolite, CaCO3, cellulose or luffa flour had lower pore volume but higher Young's modulus and stress values compared to unfilled samples.Article Citation - WoS: 39Citation - Scopus: 46Synergistic Effect of Metal Soaps and Natural Zeolite on Poly(vinyl Chloride) Thermal Stability(John Wiley and Sons Inc., 2005) Atakul, Sevdiye; Balköse, Devrim; Ülkü, SemraThe synergistic effect of metal soaps (zinc stearate and calcium stearate) and/or natural zeolite (clinoptilolite) on PVC thermal stability was investigated. For this purpose, PVC plastisol was prepared by mixing poly(vinyl chloride) (PVC) and dioctyl phthalate (DOP) and stabilized with different amounts of metal soaps and zeolite. Kinetic studies of dehydrochlorination at 140 and 160°C were done for unstabilized and stabilized PVC plastigels using 763 PVC Thermomat equipment. The stabilizing effect of zeolite on the increase in the induction period of the sample was considered to result from the absorption of HCl, a property that was thought to reduce the autocatalytic effect of HCl evolved at the initial stages of dehydrochlorination. Since the induction time of the sample having 0.53% of zinc stearate and 0.53% of zeolite was higher than those of the PVC plastigels having only zinc stearate or zeolite, the synergistic effect on thermal stability was observed at low leveles of these additives.Article Citation - WoS: 42Citation - Scopus: 42Natural Zeolite Polypropylene Composite Film Preparation and Characterization(John Wiley and Sons Inc., 2001) Özmıhçı, Filiz; Balköse, Devrim; Ülkü, SemraIn this research, the preparation and characterization of polypropylene (PP) and natural zeolite composites were studied. Natural zeolite mined in Gördes, Turkey was used as an alternative filler to CaCO3. Films were prepared by the extrusion of PP, and surface-modified zeolite was made by polyethylene glycol 4000 with 2-4% zeolite. Zeolite-filled composites had densities between 0.73 and 0.83 g/cm3 and had void fractions of 0.07-0.20. Although the permeability of water vapour through 2% zeolite-filled composites was very small, 4% zeolite-filled films had very high permeabilities. The yield stresses of 2-4% zeolite-containing films were around 26-27 N/mm2 and were lower than that of PP, which indicated no adhesion between PP and zeolite. The effect of zeolite on the thermal degradation behaviour in air and in a N2 atmosphere was also studied. In air, zeolites did not cause the oxidation of PP. In a N2 atmosphere, although the start of the thermal degradation of PP was retarded by zeolite, composites degraded at a faster rate than PP once the degradation started. At a processing temperature of 200°C, zeolites had no effect on the degradation of PP.