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Ghadami A.,Iran Polymer And Petrochemical Institutepo Box 14965 115Tehran Iran | Ehsani M.,Iran Polymer And Petrochemical Institutepo Box 14965 115Tehran Iran | Khonakdar H.A.,Leibniz Institute of Polymer Research
Journal of Vinyl and Additive Technology | Year: 2016

This study is concerned with morphological and rheological behavior of several systems based on poly(ethylene terephthalate) (PET), poly(ethylene-2,6-naphthalene) (PEN), PET/PEN blend, and their graphene-filled nanocomposites. The composites were prepared by using a melt-mixing method and analyzed by scanning electron microscopy and transmission electron microscopy techniques. It was observed that the graphene nanosheets were almost distributed uniformly, especially in the blend matrix. The applied mixing method was easily able to disperse nanographene as well as the initial aggregates in polyester and the blend system. By performing rheological examinations, the elastic modulus, viscosity, loss curve, and relaxation spectra of the samples were fully investigated. The presence of graphene had different effects on rheological properties such as viscosity and modulus in two polyester matrices and their blends. In all nanocomposite samples, with the addition of 1 wt% graphene, the elasticity level dropped relative to that of neat polyesters. In PEN nanocomposites, the tanδ peak appeared with the addition of graphene. However, in PET nanocomposites, the tanδ peak developed at higher frequency, with a low percentage of graphene nanosheets, and became narrower at greater quantity, compared with neat PET. By addition of nanographene into the blend, the damping factor increased. The relaxation spectra, H (τ), helped to better understand the viscoelastic properties in the long-time region, and it was demonstrated that the graphene sheets retarded the relaxation process of polyesters in the molten state. The results of relaxation spectra and storage modulus agreed with each other, and similar trends were observed in all the samples under examination. © 2016 Society of Plastics Engineers. Source


Naderi G.,Iran Polymer And Petrochemical Institutepo Box 14965 115Tehran Iran | Khosrokhavar R.,Iran Polymer And Petrochemical Institutepo Box 14965 115Tehran Iran | Shokoohi S.,Polymer Science And Technology Divisionresearch Institute Of Petroleum Industrypo Box 14115 143Tehran Iran | Bakhshandeh G.R.,Iran Polymer And Petrochemical Institutepo Box 14965 115Tehran Iran | Ghoreishy M.H.R.,Iran Polymer And Petrochemical Institutepo Box 14965 115Tehran Iran
Journal of Vinyl and Additive Technology | Year: 2014

Dynamically vulcanized thermoplastic elastomer (TPE) nanocomposites based on polypropylene (PP), ethylene-propylene diene monomer (EPDM) and cloisite 15A were prepared via direct melt mixing in a co-rotating twin-screw extruder. The mixing process was carried out with optimized processing parameters (barrel temperature=180°C; screw speed=150 rpm; and feeding rate=0.2 kg/hr). The formulation used to prepare the nanocomposites was fixed to 75/20/5 (PP/EPDM/Cloisite©15A), expressed in mass fraction. Effect of mixing sequence on the properties of vulcanized and unvulcanized (TPE) nanocomposites prepared under similar conditions was investigated using X-ray diffraction (XRD) and a tensile testing machine. Results showed that the sequence of mixing does affect the properties of final TPE nanocomposites. Accordingly, nanocomposite samples prepared through mixing the preblended PP/clay masterbatch with EPDM phase, show better clay dispersion within the polymer matrix. © 2014 Society of Plastics Engineers. Source


Salehi S.,Iran Polymer And Petrochemical Institutepo Box 14965 115Tehran Iran | Ehsani M.,Iran Polymer And Petrochemical Institutepo Box 14965 115Tehran Iran | Khonakdar H.A.,Iran Polymer And Petrochemical Institutepo Box 14965 115Tehran Iran
Journal of Vinyl and Additive Technology | Year: 2015

In this work, poly(methyl methacrylate)/(glass flake) (GF) composites were prepared with different compositions via melt mixing. The effect of the filler ingredient on thermal behavior, morphology, and mechanical and optical properties was investigated by using various techniques, namely differential scanning calorimetry, ultraviolet-visible spectra, mechanical testing, and scanning electron microscopy. For evaluating the level of dispersion of particles, energy dispersive X-ray analysis was performed. Differential scanning calorimetry analysis showed that the glass transition temperature of the samples slightly increased by increasing GF content. Scanning electron microscopy images showed that sized flakes were uniformly dispersed within poly(methyl methacrylate). Energy dispersive X-ray analysis images of samples with different inclusions of GFs showed that the appearance of white dense spots represents the GF particles. It was found that the presence of 0.5 wt% of GF in composites gave more transparency than the other compositions. Furthermore, this composition indicated maximum tensile strength and elongation-at-break values in comparison with the other compositions. © 2015 Society of Plastics Engineers. Source

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