Browsing by Author "Temiz, Melisa"

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New Approach Study for the Evaluation of Epdm Rubber Waste
(2022) Temiz, Melisa; Özmeral, Nimet; Kocaman, Süheyla; Cerit, Alaaddin; Ahmetli, Gülnare
Ethylene propylene diene monomer rubber (EPDM) finds applications in several industrial branches due to its properties. EPDM (ethylene propylene diene monomer) is an important synthetic rubber and is used in many different sectors. In parallel with the increase in the amount of use, EPDM waste occurs. EPDM wastes are not likely to be remelted and reprocessed due to their cross-linking and are a significant loss for the plastics industry and are often consumed as fuel. Another method of evaluating EPDM residues is to reduce them to small sizes and use them as fillers in different polymers. In this study, new epoxy composites were created using EPDM waste filler. EPDM waste was used in bisphenol-A type epoxy resin at a ratio of 5-10-15-20-30 wt%, either alone or as a hybrid filler with nano-carbon black (CB). The EPDM:CB ratio was selected as 1:1, 1:3, and 3:1 by weight. The composites were prepared according to ASTM D 638 standards using the casting technique. Composites’morphology was characterized by Scanning Electron Microscopy (SEM). Effect of EPDM:CB ratio, filler amount, water sorption, and low temperature on the mechanical properties of the composites were investigated. In order to determine the effect of water sorption and low temperature, the samples were tested for 3-21 days. A decrease was observed also in the mechanical properties (tensile strength, e-modulus, and hardness) of 30 wt% filler composites formed with both EPDM and hybrid filler, considering the effect of low temperature (freezing) and water sorption. Moreover, the mechanical properties of composites decreased as the test time increased.
Citation - WoS: 14
Citation - Scopus: 15
Newly Epoxy Resin Synthesis From Citric Acid and the Effects of Modified Almond Shell Waste With Different Natural Acids on the Creation of Bio-Based Composites
(Elsevier, 2024) Kocaman, Süheyla; Ahmetli, Gülnare; Temiz, Melisa
Synthesis of sustainable and bio-based epoxy resins that can replace petro-based and potentially harmful existing epoxy resins is important. In this sense, a novel biobased epoxy resin (ECiA) was synthesized through the esterification reaction of biobased citric acid (CiA) with epichlorohydrin (ECH). The chemical structure of ECiA was verified using FT-IR, 1H NMR, MALDI-TOF mass spectrometry, and epoxy group determination. Moreover, two biobased carboxylic acids-oxalic (OA) and linoleic (LA) acids were used in the chemical treatment process. Raw (ASh) and acid-modified AShs (LA-ASh and OA-ASh) were applied as inexpensive natural reinforcement materials in the bisphenol A-type epoxy resin (ER)-ECiA blend matrix system. The composites were produced with 10-20-30-40-50 % of ASh particles inserted in the epoxy blend matrix, and the mechanical properties, thermal behavior, dynamic-machanical properties, water absorption, and surface wettability were determined. The investigation highlighted the impact of modifying ER and reinforcing elements on the quality of the composite materials. Chemical treatments show an enhancement in adhesion between the ASh fillers and ER-ECiA matrix, as evidenced by the morphological results. The chemically modified AShs-based composites exhibit higher tensile strengths compared to both the neat ER-ECiA and untreated ASh composites. The study revealed that the composite material consisting of 15 wt% LA-ASh (70:30 wt%) demonstrated elevated values for tensile strength (88.9 MPa) and elasticity modulus (E-modulus) (7.7 GPa). TGA analysis showed that AShs improved the thermal stability of pure ER-ECiA to a certain extent. Composites prepared with modified AShs exhibited hydrophobic surfaces. According to DSC and DMA results, the glass transition temperatures (Tg) of the composites were found to be higher than the pure ER-ECiA mixture. The same results are valid for the degrees of cure calculated from FT-IR spectra.