Chemical Engineering / Kimya Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/14

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Author: search.filters.author.Ülkü, SemraSubject: search.filters.subject.Mechanical properties

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  • Article
    Citation - WoS: 71
    Citation - Scopus: 87
    Influence of Surface Modification of Fillers and Polymer on Flammability and Tensile Behaviour of Polypropylene-Composites
    (Elsevier Ltd., 2006) Demir, Hasan; Balköse, Devrim; Ülkü, Semra
    An intumescent system consisting of ammonium polyphosphate (APP) as an acid source and blowing agent, pentaerythritol (PER) as a carbonific agent and natural zeolite (clinoptilolite, Gördes II) as a synergistic agent was used in this study to enhance flame retardancy of polypropylene (FR-PP). Zeolite was incorporated into flame retardant formulation at four different concentrations (1, 2, 5, and 10 wt%) to investigate synergism with the flame retardant materials. Filler content was fixed at 30 wt% of total amounts of flame retardant PP composites. Zeolite and APP were treated with two different coupling agents namely, 3-(trimethoxysilyl)-1-propanethiol and (3-aminopropyl)-triethoxysilane for investigation of the influence of surface treatments on mechanical properties and flame retardant performance of composites. Maleic anhydride grafted polypropylene (MAPP) was used for making polypropylene hydrophilic. Flammability of FR-PP composites was measured by the determination of limiting oxygen index (LOI). The LOI values reached to a maximum value of 41% for mercapto silane treated APP:PER (2:1) PP composite containing 5 wt% zeolite. The tensile strength of composites was increased by the addition of MAPP and elongation at break of composites was increased with silane treatments.
  • Article
    Citation - WoS: 183
    Citation - Scopus: 190
    The Effect of Interfacial Interactions on the Mechanical Properties of Polypropylene/Natural Zeolite Composites
    (Elsevier Ltd., 2004) Metin, Dildare; Tıhmınlıoğlu, Funda; Balköse, Devrim; Ülkü, Semra
    The effect of interfacial interactions on the mechanical properties of polypropylene (PP)/natural zeolite composites was investigated under dry and wet conditions. Interfacial interactions were modified to improve filler compatibility and mechanical properties of the composites by surface treatment of natural zeolite with a non-ionic surface modifier; 3 wt% polyethylene glycol (PEG) and three different types of silane coupling agents; 3-aminopropyltriethoxysilane (AMPTES), methyltriethoxysilane (MTES) and 3-mercaptopropyltrimethoxysilane (MPTMS), at four different concentrations (0.5-2 wt%). PP composites containing (2-6 wt%) zeolite were prepared by an extrusion technique. The tensile properties of the composites determined as a function of the filler loading and the concentration of the coupling agents were found to vary with surface treatment of zeolite. Silane treatment indicated significant improvements in the mechanical properties of the composites. According to the dry and wet tensile test results, the maximum improvement in the mechanical properties was obtained for the PP composites containing 1 wt% AMPTES treated zeolite. The improvement in the interfacial interaction was confirmed using a semi-empirical equation developed by Pukanszky. Good agreement was obtained between experimental data and the Pukanszky model prediction. Scanning electron microscopy studies also revealed better dispersion of silane treated filler particles in the PP matrix.