Yazar "Ozdogan Tasci, Reyhan" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • Küçük Resim Yok
    Öğe
    Grafting of POSS Hybrid Nanoparticles onto Poly(Vinyl Chloride) via Diels-Alder Click Reaction
    (Wiley-V C H Verlag Gmbh, 2025) Ozdogan Tasci, Reyhan; Tasdelen, Mehmet Atilla
    In this study, commercially available PVC was successfully modified with POSS hybrid nanoparticles at various molar ratios via catalyst-free Diels-Alder (DA) click chemistry, achieved by simple heating at approximately 80 degrees C. Furan and maleimide clickable groups were independently attached to PVC and aminopropyl isobutyl POSS through nucleophilic substitution reactions. However, furan functionalization of Poly(vinyl chloride) (PVC) led to partial chain scission and HCl elimination, confirmed by gel permeation chromatography (GPC) analysis, resulting in reduced molecular weight and mechanical properties. The furan functionalization degree was 3.67% (H-1-NMR) and 3.98% (elemental analysis). Among the modified samples, only PVC-g-POSS-1:0.25 (PVC:POSS molar ratio) was soluble in DMSO-d(6), with a grafting degree of 3.78% and DA reaction efficiency of 97.08%. Chemical grafting improved thermal and mechanical properties significantly. The glass transition temperature increased from 60.4 degrees C (neat PVC) to 84.1 degrees C, and the 50% degradation onset rose from 254.02 degrees C to 362.11 degrees C. Mechanical testing showed enhanced performance (yield stress: 14.2 MPa; elongation: 69.4%; elastic modulus: 300.6 MPa), outperforming physically mixed controls. SEM and TEM analyses showed that the best polyhedral oligomeric silsesquioxanes (POSS) dispersion occurred in PVC-g-POSS-1:0.25, with a relatively uniform distribution. As the POSS content increased in PVC-g-POSS-1:0.5, larger aggregates (>200 nm) formed, indicating stronger nanoparticle interactions and reduced dispersion.
  • Küçük Resim Yok
    Öğe
    Polyester/clay nanocomposite synthesis via metal-free azide-alkyne click reaction
    (Taylor & Francis Inc, 2025) Ozdogan Tasci, Reyhan; Daglar, Ozgun; Durmaz, Hakan; Tasdelen, Mehmet Atilla
    A polyester/montmorillonite (MMT) nanocomposite is synthesized via metal-free azide-alkyne 1,3-dipolar cycloaddition (metal-free AAC) click reaction. An aliphatic polyester, poly(1,4-butane diol acetylene dicarboxylate), bearing electron-deficient alkyne groups and an azide-functionalized montmorillonite were prepared following literature procedures, then coupled at room temperature for 24 h at varied clay loadings (1, 5, and 10 wt.%) to yield the nanocomposites. Structural, thermal and morphological features of the nanocomposites are evaluated with various characterization techniques. Under nitrogen atmosphere, all nanocomposites showed enhanced thermal stability with one-step degradation, and the char yield increased by similar to 30% at the highest clay loading relative to the neat polyester. DSC revealed higher transition temperatures, with melting temperature up by similar to 3% and crystallization temperature up by similar to 11% at maximum loading, consistent with nucleation by silicate platelets. TEM and XRD evidenced mixed exfoliated and intercalated morphologies. Overall, the metal-free AAC click approach affords well-dispersed, thermally reinforced polyester/clay nanocomposites under mild, catalyst-free conditions.