Chemical Engineering / Kimya Mühendisliği

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

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Author: search.filters.author.Demir, HasanSubject: search.filters.subject.Polypropylenes

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Now showing 1 - 2 of 2
  • Article
    Citation - WoS: 324
    Citation - Scopus: 356
    The Effect of Fiber Surface Treatments on the Tensile and Water Sorption Properties of Polypropylene-Luffa Fiber Composites
    (Elsevier Ltd., 2006) Demir, Hasan; Atikler, Ulaş; Balköse, Devrim; Tıhmınlıoğlu, Funda
    The effects of coupling agents on the mechanical, morphological, and water sorption properties of luffa fiber (LF)/polypropylene(PP) composites were studied. In order to enhance the interfacial interactions between the PP matrix and the luffa fiber, three different types of coupling agents, (3-aminopropyl)-triethoxysilane (AS), 3-(trimethoxysilyl)-1-propanethiol (MS), and maleic anhydride grafted polypropylene (MAPP) were used. The PP composites containing 2-15 wt% of LF were prepared in a torque rheometer. The tensile properties of the untreated and treated composites were determined as a function of filler loading. Tensile strength and Young's modulus increased with employment of the coupling agents accompanied by a decrease in water absorption with treatment due to the better adhesion between the fiber and the matrix. The maximum improvement in the mechanical properties was obtained for the MS treated LF composites. The interfacial interactions improved the filler compatibility, mechanical properties, and water resistance of composites. The improvement in the interfacial interaction was also confirmed by the Pukanszky model. Good agreement was obtained between experimental data and the model prediction. Morphological studies demonstrated that better adhesion between the fiber and the matrix was achieved especially for the MS and AS treated LF composites. Atomic force microscope (AFM) studies also showed that the surface roughness of LFs decreased with the employment of silane-coupling agents.
  • Article
    Citation - WoS: 187
    Citation - Scopus: 208
    Synergistic Effect of Natural Zeolites on Flame Retardant Additives
    (Elsevier Ltd., 2005) Demir, Hasan; Arkış, Esen; Balköse, Devrim; Ülkü, Semra
    The thermal degradation and flammability of intumescent fire-retardant polypropylene matrix composites consisting of ammonium polyphosphate (APP) as an acid source and blowing agent, pentaerythritol (PER) as a carbonisation agent and natural zeolite (clinoptilolite rich, Gördes II) as a synergistic agent were examined. APP and PER combinations were examined at different ratios (0.25, 0.33, 0.5, 1, 2, 3, and 4) for optimisation of the formulation for flame retardancy. The zeolite was incorporated into flame retardant formulation at four different concentrations (1, 2, 5, and 10 wt%) to investigate the synergism between the flame retardant materials. The thermal degradation and flammability of composites were characterized by thermogravimetric analysis (TGA) and by limiting oxygen index (LOI) measurement and horizontal burning (HB) tests. A synergistic effect in flame retardancy was observed when natural zeolites were used in combination with APP and PER.