Browsing by Author "Dogan, Mehmet"

Now showing 1 - 5 of 5

Effect of Various Enzymatic Treatments on the Mechanical Properties of Coir Fiber/Poly(lactic Acid) Biocomposites
(Sage Publications Ltd, 2021) Coskun, Kubra; Mutlu, Aysenur; Dogan, Mehmet; Bozaci, Ebru
The effects of enzymatic treatments on the properties of coir fiber-reinforced poly(lactic acid) (PLA) were not found in the literature. Accordingly, the effects of various enzymatic treatments on the mechanical performance of the coir fiber-reinforced PLA composites were investigated in the current study. Four different enzymes, namely lipase, lactase, pectinase, and cellulase, were used. The mechanical properties of the composites were determined by the tensile, flexural, impact tests, and dynamic mechanical analysis. According to the test results, the use of enzyme treated coir fibers affected the mechanical properties except for the flexural properties with different extents depending upon their type. The tensile strength increased with the treatments of lipase and lactase, while the treatments with pectinase and cellulase had no remarkable effect. The impact strength was improved with enzymatic treatments except for pectinase. All enzymatic treatments improved the elastic modulus below the glass transition temperature. In brief, enzymatic treatments improved the interfacial adhesion between coir fiber and PLA via the waxes and fatty acids removal and/or the increment in surface roughness.
The Fez-Hat Struggle in the Context of Symbolic Values in the Turkish Novel
(Istanbul Univ, 2021) Dogan, Mehmet
Dress has a symbolic value and meaning that can be an indicator of the civilization, identity, political preferences, position or economic status of the person. Although this decisiveness is sometimes misleading as there is a relative uniformization of dress-clothing with globalization, it can be said that the sharpest distinction is seen through dress-clothing in periods and countries where civilizations are separated from each other by sharp lines. Especially in traditionalist societies that resist change, clothing preserves its symbolic value and meaning as a taboo. The most important garments that carry a symbolic meaning and value, at least in the late 19th and early 20th centuries that this article is about, are undoubtedly the headdresses. Attempts to change the headlines were actually seen as symbols of radical changes and a sign of obedience to power. In this article, we will try to determine the perception, meaning and values of the turban worn by the madrasians and Sufists, the fez, the headdress of the Muslim Ottoman community, the kalpak used by the supporters of the Kuvveyi Milliye, and the hat taken from the West in the Turkish society based on literary works.
Fire Retardant Properties of Chicken Feather/Tpu Composites Containing Phosphorus Fillers
(Emerald Group Publishing Ltd, 2023) Mutlu, Aysenur; Dogan, Mehmet
The aim of this study was to enhance the flame-retardant properties of chicken-feather-reinforced thermoplastic polyurethane (TPU) composites by incorporating three different phosphorus-based flame retardants - namely, aluminum hypophosphite (AHP), ammonium polyphosphate (APP) and aluminum diethyl phosphinate (AlPi) - at concentrations of 5, 10 and 20 wt%. The effectiveness of the additives was evaluated through various tests, including limiting oxygen index test, vertical burning test (vertical UL 94), thermogravimetric analysis and mass loss calorimeter test. The results indicated that all three additives exhibited flame-retardant properties in both the condensed and gas phases, but APP and AHP performed better than AlPi due to their enhanced char-formation capabilities. The flame-retardant effectiveness of the additives decreased in the order of APP > AHP > AlPi.
Performance Evaluation of Melamine Derivatives as Flame Retardant Additive in Chicken Feather Containing Thermoplastic Polyurethane Biocomposites
(Sage Publications Ltd, 2023) Mutlu, Aysenur; Tayfun, Umit; Dogan, Mehmet
The objective of this research is to examine the potential use of melamine derivatives namely melamine cyanurate (MC), melamine phosphate (MP), and melamine polyphosphate (MPP) as flame retardant additives in chicken feather (CF) containing thermoplastic polyurethane (TPU). The performances of the composites are evaluated using limiting oxygen index (LOI), vertical UL-94 (UL-94 V), and mass loss calorimeter (MLC) tests. The V0 rating is achieved with the addition of 10 wt% MC, 20 wt% MP, and MPP. The performances of the additives are ranked in the ascending order of MC, MP, and MPP in LOI test. MP and MPP show distinct better performance than MC in the condensed phase. However, the gas phase action of MC is much better. than MP, and MPP. The lowest pHRR (103 Kw/m(2)), THE (39 MJ/m(2)), and THE/TML ratio (1.4 MJ/m(2)g) are observed with the use of 20 wt% MPP, MP, and MC, respectively.
Potential Use of Melamine Phytate as a Flame-Retardant Additive in Chicken Feather-Containing Thermoplastic Polyurethane Biocomposites
(Amer Chemical Soc, 2023) Mutlu, Aysenur; Erdem, Aysegul; Dogan, Mehmet
Using waste materials such as chicken feathers (CF) andbiobasedflame-retardant additives including melamine phytate (MPht) has becomean effective approach for environmentally friendly and sustainableproduction in recent years. This study explores the flame retardanteffectiveness of MPht in thermoplastic polyurethane (TPU)-based biocompositescontaining CF. The characterizations of the composites are performedthrough thermal gravimetric analysis (TGA), limiting oxygen index(LOI), vertical UL-94 (UL-94 V), and mass loss calorimetry (MLC) tests.According to the test results, the highest UL-94 V rating of V0, aLOI value of 29.4%, and the lowest peak heat release rate (pHRR) (110Kw/m(2)) and total heat evolved (THE) (39 MJ/m(2)) values are obtained with the use of 20 wt % MPht. It is demonstratedthat MPht acts as an effective flame-retardant filler through theformation of intumescent char in the condensed phase and flame dilutionin the gas phase.