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  • Küçük Resim Yok
    Öğe
    Microstructural and dielectric properties of naphthalene based polyamide/?-Ni(OH)2 nanocomposites
    (Bentham Science Publishers B.V., 2018) Sezer S.; Öz E.; Altin S.; Vural S.; Gültek A.; Köytepe S.; Nilüfer Kıvılcım F.
    Background: Aromatic polyamides are important materials having outstanding thermal, electronic and mechanical properties among high performance polymers and industrial plastics. In addition, aromatic polyamides can be utilized in electronic devices with their low dielectric constant which indicates the storage capacity of these devices. Objective: Free volume is very important for dielectric materials and increase in free volume of a polymer reduces its dielectric constant. The aims of the current study are to create free volume in the bulk polyamide structure and to reduce the dielectric constant by using ?-Ni(OH)2 particles. Method: The composites obtained from ?-Ni(OH)2 (flower-like nanoparticles) in a naphthalene-based polyamide matrix were prepared. Firstly, ?-Ni(OH)2 nanoparticles were synthesized by microwave-assisted solvothermal technique under various reaction conditions. Then, polyamide/?-Ni(OH)2 composites were prepared via direct dispersion methods at different reinforcement ratios. Results: ?-Ni(OH)2 (flower-like nanoparticles) and polyamide/?-Ni(OH)2 composites were prepared successfully. Our studies showed that the dispersion of ?-Ni(OH)2 nanoparticles in polyamide matrix is homogenous and prepared composites have good thermal and dielectric properties with promising results for electronic industry. Conclusion: Dielectric properties of the prepared composites decrease with increasing ?-Ni(OH)2 nanoparticle content and all composites show low dielectric constant when ?-Ni(OH)2 nanoparticle content is over 1 wt.% compared to the pure polyamide. © 2018 Bentham Science Publishers.
  • Küçük Resim Yok
    Öğe
    Synthesis and characterization of polyimides prepared from optically active (R,R) and (S,S)-1,3-bis(p-N,N?-dimethylaminobenzyl)-perhydrobenzimidazol- 2-thion
    (2007) Yi?it M.; Seçkin T.; Köytepe S.; Çetinkaya E.
    This paper presents the synthesis and characterization of polyimides containing a chiral (R,R) or (S,S) 1,3-bis(p ? N,N?-dimethylaminobenzyl)- perhydrobenzimidazol-2-thion unit in the backbone. The reactions occur between equimolar amounts of a dianhydride and an aromatic dimethylamine in the presence of the solvent N-methyl-2-pyrollidone (NMP). In this work, the chiral monomer RR and SS -1,3-bis(p ? N,N?-dimethylaminobenzyl)-perhydrobenzimidazol-2- thion were used as diamines. The polyimides obtained were characterized by thermogravimetry (TGA), differential thermal analysis (DTA), differential scanning calorimeter (DSC), infrared spectroscopy (FT-IR), and gel permeation chromatography (GPC). It was found that the composition of the polymer had a significant effect upon the thermal behavior of the material. © TÜBİTAK.